This guide covers concepts as well as practical details needed by developers to use the Node.js runtime.

1. What is Node.js

Node.js is based on the V8 JavaScript engine from Google and allows you to write server-side JavaScript applications. It provides an I/O model based on events and non-blocking operations that enables you to write efficient applications. Node.js also provides a large module ecosystem called npm. Check out Additional Resources for further reading on Node.js.

The Node.js runtime enables you to run Node.js applications and services on OpenShift while providing all the advantages and conveniences of the OpenShift platform such as rolling updates, continuous delivery pipelines, service discovery, and canary deployments. OpenShift also makes it easier for your applications to implement common microservice patterns such as externalized configuration, health check, circuit breaker, and failover.

2. Missions and cloud-native development on OpenShift

When developing applications on OpenShift, you can use missions and boosters to kickstart your development.

Missions

Missions are working applications that showcase different fundamental pieces of building cloud native applications and services.

A mission implements a Microservice pattern such as:

  • Creating REST APIs

  • Interoperating with a database

  • Implementing the Health Check pattern

You can use missions for a variety of purposes:

  • A proof of technology demonstration

  • A teaching tool, or a sandbox for understanding how to develop applications for your project

  • They can also be updated or extended for your own use case

Boosters

A booster is the implementation of a mission in a specific runtime. Boosters are preconfigured, functioning applications that demonstrate core principles of modern application development and run in an environment similar to production.

Each mission is implemented in one or more runtimes. Both the specific implementation and the actual project that contains your code are called a booster.

For example, the REST API Level 0 mission is implemented for these runtimes:

3. Available missions and boosters for Node.js

The following boosters are available for Node.js.

3.1. REST API Level 0 mission - Node.js booster

Mission proficiency level: Foundational.

What the REST API Level 0 Mission Does

The REST API Level 0 mission shows how to map business operations to a remote procedure call endpoint over HTTP using a REST framework. This corresponds to Level 0 in the Richardson Maturity Model. Creating an HTTP endpoint using REST and its underlying principles to define your API lets you quickly prototype and design the API flexibly.

This booster introduces the mechanics of interacting with a remote service using the HTTP protocol. It allows you to:

  • Execute an HTTP GET request on the api/greeting endpoint.

  • Receive a response in JSON format with a payload consisting of the Hello, World! String.

  • Execute an HTTP GET request on the api/greeting endpoint while passing in a String argument. This uses the name request parameter in the query string.

  • Receive a response in JSON format with a payload of Hello, $name! with $name replaced by the value of the name parameter passed into the request.

3.1.1. Viewing the booster source code and README

Prerequisites

One of the following:

  • Access to developers.redhat.com/launch

  • Fabric8 Launcher installed on a Single-node OpenShift Cluster

Procedure
  1. Use the Fabric8 Launcher tool to generate your own version of the booster.

  2. View the generated GitHub repository or download and extract the ZIP file that contains the booster source code.

3.1.2. REST API Level 0 design tradeoffs

Table 1. Design Tradeoffs
Pros Cons
  • The booster enables fast prototyping.

  • The API Design is flexible.

  • HTTP endpoints allow clients to be language-neutral.

  • As an application or service matures, the REST API Level 0 approach might not scale well. It might not support a clean API design or use cases with database interactions.

    • Any operations involving shared, mutable state must be integrated with an appropriate backing datastore.

    • All requests handled by this API design are scoped only to the container servicing the request. Subsequent requests might not be served by the same container.

3.1.3. Deploying the REST API Level 0 booster to OpenShift Online

Use one of the following options to execute the REST API Level 0 booster on OpenShift Online.

Although each method uses the same oc commands to deploy your application, using developers.redhat.com/launch provides an automated booster deployment workflow that executes the oc commands for you.

Deploying the booster using developers.redhat.com/launch
Prerequisites
Procedure
  1. Navigate to the developers.redhat.com/launch URL in a browser and log in.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on OpenShift Online using the oc command-line client, you need to authenticate the client using the token provided by the OpenShift Online web interface.

Prerequisites
Procedure
  1. Navigate to the OpenShift Online URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your OpenShift Online account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the REST API Level 0 booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new project in OpenShift.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Use npm to start the deployment to OpenShift.

    $ npm install && npm run openshift

    These commands install any missing module dependencies, then using the Nodeshift module, deploy the booster on OpenShift.

  5. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                             READY     STATUS      RESTARTS   AGE
    MY_APP_NAME-1-aaaaa               1/1       Running     0          58s
    MY_APP_NAME-s2i-1-build           0/1       Completed   0          2m

    The MY_APP_NAME-1-aaaaa pod should have a status of Running once it is fully deployed and started. Your specific pod name will vary. The number in the middle will increase with each new build. The letters at the end are generated when the pod is created.

  6. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
    MY_APP_NAME         MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME      MY_APP_NAME      8080

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the application.

3.1.4. Deploying the REST API Level 0 booster to Single-node OpenShift Cluster

Use one of the following options to execute the REST API Level 0 booster locally on Single-node OpenShift Cluster:

Although each method uses the same oc commands to deploy your application, using Fabric8 Launcher provides an automated booster deployment workflow that executes the oc commands for you.

Getting the Fabric8 Launcher tool URL and credentials

You need the Fabric8 Launcher tool URL and user credentials to create and deploy boosters on Single-node OpenShift Cluster. This information is provided when the Single-node OpenShift Cluster is started.

Prerequisites
Procedure
  1. Navigate to the console where you started Single-node OpenShift Cluster.

  2. Check the console output for the URL and user credentials you can use to access the running Fabric8 Launcher:

    Example Console Output from a Single-node OpenShift Cluster Startup
    ...
    -- Removing temporary directory ... OK
    -- Server Information ...
       OpenShift server started.
       The server is accessible via web console at:
           https://192.168.42.152:8443
    
       You are logged in as:
           User:     developer
           Password: developer
    
       To login as administrator:
           oc login -u system:admin
Deploying the booster using the Fabric8 Launcher tool
Prerequisites
Procedure
  1. Navigate to the Fabric8 Launcher URL in a browser.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on Single-node OpenShift Cluster using the oc command-line client, you need to authenticate the client using the token provided by the Single-node OpenShift Cluster web interface.

Prerequisites
Procedure
  1. Navigate to the Single-node OpenShift Cluster URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your Single-node OpenShift Cluster account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the REST API Level 0 booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new project in OpenShift.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Use npm to start the deployment to OpenShift.

    $ npm install && npm run openshift

    These commands install any missing module dependencies, then using the Nodeshift module, deploy the booster on OpenShift.

  5. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                             READY     STATUS      RESTARTS   AGE
    MY_APP_NAME-1-aaaaa               1/1       Running     0          58s
    MY_APP_NAME-s2i-1-build           0/1       Completed   0          2m

    The MY_APP_NAME-1-aaaaa pod should have a status of Running once it is fully deployed and started. Your specific pod name will vary. The number in the middle will increase with each new build. The letters at the end are generated when the pod is created.

  6. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
    MY_APP_NAME         MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME      MY_APP_NAME      8080

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the application.

3.1.5. Deploying the REST API Level 0 booster to OpenShift Container Platform

The process of creating and deploying boosters to OpenShift Container Platform is similar to OpenShift Online:

Prerequisites
Procedure

3.1.6. Interacting with the unmodified REST API Level 0 booster for Node.js

The booster provides a default HTTP endpoint that accepts GET requests.

Prerequisites
  • Your application running

  • The curl binary or a web browser

Procedure
  1. Use curl to execute a GET request against the booster. You can also use a browser to do this.

    $ curl http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/greeting
    {"content":"Hello, World!"}
  2. Use curl to execute a GET request with the name URL parameter against the booster. You can also use a browser to do this.

    $ curl http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/greeting?name=Sarah
    {"content":"Hello, Sarah!"}
From a browser, you can also use a form provided by the booster to perform these same interactions. The form is located at the root of the project http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME.

3.2. Externalized Configuration mission - Node.js booster

Mission proficiency level: Foundational.

The Externalized Configuration mission provides a basic example of using a ConfigMap to externalize configuration. ConfigMap is an object used by OpenShift to inject configuration data as simple key and value pairs into one or more Linux containers while keeping the containers independent of OpenShift.

This mission shows you how to:

  • Set up and configure a ConfigMap.

  • Use the configuration provided by the ConfigMap within an application.

  • Deploy changes to the ConfigMap configuration of running applications.

3.2.1. The externalized configuration design pattern

Whenever possible, externalize the application configuration and separate it from the application code. This allows the application configuration to change as it moves through different environments, but leaves the code unchanged. Externalizing the configuration also keeps sensitive or internal information out of your code base and version control. Many languages and application servers provide environment variables to support externalizing an application’s configuration.

Microservices architectures and multi-language (polyglot) environments add a layer of complexity to managing an application’s configuration. Applications consist of independent, distributed services, and each can have its own configuration. Keeping all configuration data synchronized and accessible creates a maintenance challenge.

ConfigMaps enable the application configuration to be externalized and used in individual Linux containers and pods on OpenShift. You can create a ConfigMap object in a variety of ways, including using a YAML file, and inject it into the Linux container. ConfigMaps also allow you to group and scale sets of configuration data. This lets you configure a large number of environments beyond the basic Development, Stage, and Production. You can find more information about ConfigMaps in the OpenShift documentation.

3.2.2. Externalized Configuration design tradeoffs

Table 2. Design Tradeoffs
Pros Cons
  • Configuration is separate from deployments

  • Can be updated independently

  • Can be shared across services

  • Adding configuration to environment requires additional step

  • Has to be maintained separately

  • Requires coordination beyond the scope of a service

3.2.3. Viewing the booster source code and README

Prerequisites

One of the following:

  • Access to developers.redhat.com/launch

  • Fabric8 Launcher installed on a Single-node OpenShift Cluster

Procedure
  1. Use the Fabric8 Launcher tool to generate your own version of the booster.

  2. View the generated GitHub repository or download and extract the ZIP file that contains the booster source code.

3.2.4. Deploying the Externalized Configuration booster to OpenShift Online

Use one of the following options to execute the Externalized Configuration booster on OpenShift Online.

Although each method uses the same oc commands to deploy your application, using developers.redhat.com/launch provides an automated booster deployment workflow that executes the oc commands for you.

Deploying the booster using developers.redhat.com/launch
Prerequisites
Procedure
  1. Navigate to the developers.redhat.com/launch URL in a browser and log in.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on OpenShift Online using the oc command-line client, you need to authenticate the client using the token provided by the OpenShift Online web interface.

Prerequisites
Procedure
  1. Navigate to the OpenShift Online URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your OpenShift Online account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Externalized Configuration booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new OpenShift project.

    $ oc new-project MY_PROJECT_NAME
  3. Assign view access rights to the service account before deploying your booster, so that the booster can access the OpenShift API in order to read the contents of the ConfigMap.

    $ oc policy add-role-to-user view -n $(oc project -q) -z default
  4. Navigate to the root directory of your booster.

  5. Deploy your ConfigMap configuration to OpenShift using app-config.yml.

    $ oc create configmap app-config --from-file=app-config.yml
  6. Verify your ConfigMap configuration has been deployed.

    $ oc get configmap app-config -o yaml
    
    apiVersion: v1
    data:
      app-config.yml: |-
          message : "Hello, %s from a ConfigMap !"
          level : INFO
    ...
  7. Use npm to start the deployment to OpenShift.

    $ npm install && npm run openshift

    These commands install any missing module dependencies, then using the Nodeshift module, deploy the booster on OpenShift.

  8. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                                       READY     STATUS      RESTARTS   AGE
    MY_APP_NAME-1-aaaaa               1/1       Running     0          58s
    MY_APP_NAME-s2i-1-build           0/1       Completed   0          2m

    The MY_APP_NAME-1-aaaaa pod should have a status of Running once its fully deployed and started. Your specific pod name will vary. The number in the middle will increase with each new build. The letters at the end are generated when the pod is created.

  9. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
    MY_APP_NAME         MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME      MY_APP_NAME      8080

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the application.

3.2.5. Deploying the Externalized Configuration booster to Single-node OpenShift Cluster

Use one of the following options to execute the Externalized Configuration booster locally on Single-node OpenShift Cluster:

Although each method uses the same oc commands to deploy your application, using Fabric8 Launcher provides an automated booster deployment workflow that executes the oc commands for you.

Getting the Fabric8 Launcher tool URL and credentials

You need the Fabric8 Launcher tool URL and user credentials to create and deploy boosters on Single-node OpenShift Cluster. This information is provided when the Single-node OpenShift Cluster is started.

Prerequisites
Procedure
  1. Navigate to the console where you started Single-node OpenShift Cluster.

  2. Check the console output for the URL and user credentials you can use to access the running Fabric8 Launcher:

    Example Console Output from a Single-node OpenShift Cluster Startup
    ...
    -- Removing temporary directory ... OK
    -- Server Information ...
       OpenShift server started.
       The server is accessible via web console at:
           https://192.168.42.152:8443
    
       You are logged in as:
           User:     developer
           Password: developer
    
       To login as administrator:
           oc login -u system:admin
Deploying the booster using the Fabric8 Launcher tool
Prerequisites
Procedure
  1. Navigate to the Fabric8 Launcher URL in a browser.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on Single-node OpenShift Cluster using the oc command-line client, you need to authenticate the client using the token provided by the Single-node OpenShift Cluster web interface.

Prerequisites
Procedure
  1. Navigate to the Single-node OpenShift Cluster URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your Single-node OpenShift Cluster account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Externalized Configuration booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new OpenShift project.

    $ oc new-project MY_PROJECT_NAME
  3. Assign view access rights to the service account before deploying your booster, so that the booster can access the OpenShift API in order to read the contents of the ConfigMap.

    $ oc policy add-role-to-user view -n $(oc project -q) -z default
  4. Navigate to the root directory of your booster.

  5. Deploy your ConfigMap configuration to OpenShift using app-config.yml.

    $ oc create configmap app-config --from-file=app-config.yml
  6. Verify your ConfigMap configuration has been deployed.

    $ oc get configmap app-config -o yaml
    
    apiVersion: v1
    data:
      app-config.yml: |-
          message : "Hello, %s from a ConfigMap !"
          level : INFO
    ...
  7. Use npm to start the deployment to OpenShift.

    $ npm install && npm run openshift

    These commands install any missing module dependencies, then using the Nodeshift module, deploy the booster on OpenShift.

  8. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                                       READY     STATUS      RESTARTS   AGE
    MY_APP_NAME-1-aaaaa               1/1       Running     0          58s
    MY_APP_NAME-s2i-1-build           0/1       Completed   0          2m

    The MY_APP_NAME-1-aaaaa pod should have a status of Running once its fully deployed and started. Your specific pod name will vary. The number in the middle will increase with each new build. The letters at the end are generated when the pod is created.

  9. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
    MY_APP_NAME         MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME      MY_APP_NAME      8080

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the application.

3.2.6. Deploying the Externalized Configuration booster to OpenShift Container Platform

The process of creating and deploying boosters to OpenShift Container Platform is similar to OpenShift Online:

Prerequisites
Procedure

3.2.7. Interacting with the unmodified Externalized Configuration booster for Node.js

The booster provides a default HTTP endpoint that accepts GET requests.

Prerequisites
  • Your application running

  • The curl binary or a web browser

Procedure
  1. Use curl to execute a GET request against the booster. You can also use a browser to do this.

    $ curl http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/greeting
    {"content":"Hello, World from a ConfigMap !"}
  2. Update the deployed ConfigMap configuration.

    $ oc edit configmap app-config

    Change the value for the message key to Bonjour, %s from a ConfigMap ! and save the file.

  3. Update of the ConfigMap should be read by the application within an acceptable time (a few seconds) without requiring a restart of the application.

  4. Execute a GET request using curl against the booster with the updated ConfigMap configuration to see your updated greeting. You can also do this from your browser using the web form provided by the application.

    $ curl http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/greeting
    {"content":"Bonjour, World from a ConfigMap !"}

3.3. Relational Database Backend mission - Node.js booster

Limitation: Run this booster on a Single-node OpenShift Cluster. You can also use a manual workflow to deploy this booster to OpenShift Online Pro and OpenShift Container Platform. This booster is not currently available on OpenShift Online Starter.

Mission proficiency level: Foundational.

What the Relational Database Backend Booster Does

The Relational Database Backend booster expands on the REST API Level 0 booster to provide a basic example of performing create, read, update and delete (CRUD) operations on a PostgreSQL database using a simple HTTP API. CRUD operations are the four basic functions of persistent storage, widely used when developing an HTTP API dealing with a database.

The booster also demonstrates the ability of the HTTP application to locate and connect to a database in OpenShift. Each runtime shows how to implement the connectivity solution best suited in the given case. The runtime can choose between options such as using JDBC, JPA, or accessing ORM APIs directly.

The booster application exposes an HTTP API, which provides endpoints that allow you to manipulate data by performing CRUD operations over HTTP. The CRUD operations are mapped to HTTP Verbs. The API uses JSON formatting to receive requests and return responses to the user. The user can also use an UI provided by the booster to use the application. Specifically, this booster provides an application that allows you to:

  • Navigate to the application web interface in your browser. This exposes a simple website allowing you to perform CRUD operations on the data in the my_data database.

  • Execute an HTTP GET request on the api/fruits endpoint.

  • Receive a response formatted as a JSON array containing the list of all fruits in the database.

  • Execute an HTTP GET request on the api/fruits/* endpoint while passing in a valid item ID as an argument.

  • Receive a response in JSON format containing the name of the fruit with the given ID. If no item matches the specified ID, the call results in an HTTP error 404.

  • Execute an HTTP POST request on the api/fruits endpoint passing in a valid name value to create a new entry in the database.

  • Execute an HTTP PUT request on the api/fruits/* endpoint passing in a valid ID and a name as an argument. This updates the name of the item with the given ID to match the name specified in your request.

  • Execute an HTTP DELETE request on the api/fruits/* endpoint, passing in a valid ID as an argument. This removes the item with the specified ID from the database and returns an HTTP code 204 (No Content) as a response. If you pass in an invalid ID, the call results in an HTTP error 404.

This booster does not showcase a fully matured RESTful model (level 3), but it does use compatible HTTP verbs and status, following the recommended HTTP API practices.

3.3.1. Relational Database Backend design tradeoffs

Table 3. Design Tradeoffs
Pros Cons
  • Each runtime determines how to implement the database interactions. One can use a low-level connectivity API such as JDBC, some other can use JPA, and yet another can access ORM APIs directly. Each runtime decides what would be the best way.

  • Each runtime determines how the schema is created.

  • The PostgreSQL database example provided with this mission is not backed up with persistent storage. Changes to the database are lost if you stop or redeploy the database pod. To use an external database with your mission’s pod in order to preserve changes, see the Integrating External Services chapter of the OpenShift Documentation. It is also possible to set up persistent storage with database containers on OpenShift. (For more details about using persistent storage with OpenShift and containers, see the Persistent Storage, Managing Volumes and Persistent Volumes chapters of the OpenShift Documentation).

3.3.2. Viewing the booster source code and README

Prerequisites

One of the following:

  • Access to developers.redhat.com/launch

  • Fabric8 Launcher installed on a Single-node OpenShift Cluster

Procedure
  1. Use the Fabric8 Launcher tool to generate your own version of the booster.

  2. View the generated GitHub repository or download and extract the ZIP file that contains the booster source code.

3.3.3. Deploying the Relational Database Backend booster to OpenShift Online

Use one of the following options to execute the Relational Database Backend booster on OpenShift Online.

Although each method uses the same oc commands to deploy your application, using developers.redhat.com/launch provides an automated booster deployment workflow that executes the oc commands for you.

Deploying the booster using developers.redhat.com/launch
Prerequisites
Procedure
  1. Navigate to the developers.redhat.com/launch URL in a browser and log in.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on OpenShift Online using the oc command-line client, you need to authenticate the client using the token provided by the OpenShift Online web interface.

Prerequisites
Procedure
  1. Navigate to the OpenShift Online URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your OpenShift Online account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Relational Database Backend booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new OpenShift project.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Deploy the PostgreSQL database to OpenShift. Ensure that you use the following values for user name, password, and database name when creating your database application. The booster application is pre-configured to use these values. Using different values prevents your booster application from integrating with the database.

    $ oc new-app -e POSTGRESQL_USER=luke -ePOSTGRESQL_PASSWORD=secret -ePOSTGRESQL_DATABASE=my_data openshift/postgresql-92-centos7 --name=my-database
  5. Check the status of your database and ensure the pod is running.

    $ oc get pods -w
    my-database-1-aaaaa   1/1       Running   0         45s
    my-database-1-deploy   0/1       Completed   0         53s

    The my-database-1-aaaaa pod should have a status of Running and should be indicated as ready once it is fully deployed and started. Your specific pod name will vary. The number in the middle will increase with each new build. The letters at the end are generated when the pod is created.

  6. Use npm to start the deployment to OpenShift.

    $ npm install && npm run openshift

    These commands install any missing module dependencies, then using the Nodeshift module, deploy the booster on OpenShift.

  7. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                             READY     STATUS      RESTARTS   AGE
    MY_APP_NAME-1-aaaaa       1/1       Running     0          58s
    MY_APP_NAME-s2i-1-build   0/1       Completed   0          2m

    Your MY_APP_NAME-1-aaaaa pod should have a status of Running and should be indicated as ready once it is fully deployed and started.

  8. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                     PATH      SERVICES             PORT      TERMINATION
    MY_APP_NAME   MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME      MY_APP_NAME   8080

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the application.

3.3.4. Deploying the Relational Database Backend booster to Single-node OpenShift Cluster

Use one of the following options to execute the Relational Database Backend booster locally on Single-node OpenShift Cluster:

Although each method uses the same oc commands to deploy your application, using Fabric8 Launcher provides an automated booster deployment workflow that executes the oc commands for you.

Getting the Fabric8 Launcher tool URL and credentials

You need the Fabric8 Launcher tool URL and user credentials to create and deploy boosters on Single-node OpenShift Cluster. This information is provided when the Single-node OpenShift Cluster is started.

Prerequisites
Procedure
  1. Navigate to the console where you started Single-node OpenShift Cluster.

  2. Check the console output for the URL and user credentials you can use to access the running Fabric8 Launcher:

    Example Console Output from a Single-node OpenShift Cluster Startup
    ...
    -- Removing temporary directory ... OK
    -- Server Information ...
       OpenShift server started.
       The server is accessible via web console at:
           https://192.168.42.152:8443
    
       You are logged in as:
           User:     developer
           Password: developer
    
       To login as administrator:
           oc login -u system:admin
Deploying the booster using the Fabric8 Launcher tool
Prerequisites
Procedure
  1. Navigate to the Fabric8 Launcher URL in a browser.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on Single-node OpenShift Cluster using the oc command-line client, you need to authenticate the client using the token provided by the Single-node OpenShift Cluster web interface.

Prerequisites
Procedure
  1. Navigate to the Single-node OpenShift Cluster URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your Single-node OpenShift Cluster account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Relational Database Backend booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new OpenShift project.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Deploy the PostgreSQL database to OpenShift. Ensure that you use the following values for user name, password, and database name when creating your database application. The booster application is pre-configured to use these values. Using different values prevents your booster application from integrating with the database.

    $ oc new-app -e POSTGRESQL_USER=luke -ePOSTGRESQL_PASSWORD=secret -ePOSTGRESQL_DATABASE=my_data openshift/postgresql-92-centos7 --name=my-database
  5. Check the status of your database and ensure the pod is running.

    $ oc get pods -w
    my-database-1-aaaaa   1/1       Running   0         45s
    my-database-1-deploy   0/1       Completed   0         53s

    The my-database-1-aaaaa pod should have a status of Running and should be indicated as ready once it is fully deployed and started. Your specific pod name will vary. The number in the middle will increase with each new build. The letters at the end are generated when the pod is created.

  6. Use npm to start the deployment to OpenShift.

    $ npm install && npm run openshift

    These commands install any missing module dependencies, then using the Nodeshift module, deploy the booster on OpenShift.

  7. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                             READY     STATUS      RESTARTS   AGE
    MY_APP_NAME-1-aaaaa       1/1       Running     0          58s
    MY_APP_NAME-s2i-1-build   0/1       Completed   0          2m

    Your MY_APP_NAME-1-aaaaa pod should have a status of Running and should be indicated as ready once it is fully deployed and started.

  8. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                     PATH      SERVICES             PORT      TERMINATION
    MY_APP_NAME   MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME      MY_APP_NAME   8080

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the application.

3.3.5. Deploying the Relational Database Backend booster to OpenShift Container Platform

The process of creating and deploying boosters to OpenShift Container Platform is similar to OpenShift Online:

Prerequisites
Procedure

3.3.6. Interacting with the Relational Database Backend API on Node.js

When you have finished creating your application booster, you can interact with it the following way:

Prerequisites
  • Your application running

  • The curl binary or a web browser

Procedure
  1. Obtain the URL of your application by executing the following command:

    $ oc get route MY_APP_NAME
    NAME                 HOST/PORT                                         PATH      SERVICES             PORT      TERMINATION
    MY_APP_NAME           MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME              MY_APP_NAME           8080
  2. To access the web interface of the database application, navigate to the application URL in your browser:

    http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME

    Alternatively, you can make requests directly on the api/fruits/* endpoint using curl:

    List all entries in the database:
    $ curl http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/fruits
    [ {
      "id" : 1,
      "name" : "Apple",
      "stock" : 10
    }, {
      "id" : 2,
      "name" : "Orange",
      "stock" : 10
    }, {
      "id" : 3,
      "name" : "Pear",
      "stock" : 10
    } ]
    Retrieve an entry with a specific ID
    $ curl http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/fruits/3
    {
      "id" : 3,
      "name" : "Pear",
      "stock" : 10
    }
    Create a new entry:
    $ curl -H "Content-Type: application/json" -X POST -d '{"name":"Peach","stock":1}'  http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/fruits
    {
      "id" : 4,
      "name" : "Peach",
      "stock" : 1
    }
    Update an Entry
    $ curl -H "Content-Type: application/json" -X PUT -d '{"name":"Apple","stock":100}'  http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/fruits/1
    {
      "id" : 1,
      "name" : "Apple",
      "stock" : 100
    }
    Delete an Entry:
    $ curl -X DELETE http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/fruits/1
Troubleshooting
  • If you receive an HTTP Error code 503 as a response after executing these commands, it means that the application is not ready yet.

3.4. Health Check mission - Node.js booster

Mission proficiency level: Foundational.

When you deploy an application, its important to know if it is available and if it can start handling incoming requests. Implementing the health check pattern allows you to monitor the health of an application, which includes if an application is available and whether it is able to service requests.

If you are not familiar with the health check terminology, see the Health check concepts section first.

The purpose of this use case is to demonstrate the health check pattern through the use of probing. Probing is used to report the liveness and readiness of an application. In this use case, you configure an application which exposes an HTTP health endpoint to issue HTTP requests. If the container is alive, according to the liveness probe on the health HTTP endpoint, the management platform receives 200 as return code and no further action is required. If the health HTTP endpoint does not return a response, for example if the thread is blocked, then the application is not considered alive according to the liveness probe. In that case, the platform kills the pod corresponding to that application and recreates a new pod to restart the application.

This use case also allows you to demonstrate and use a readiness probe. In cases where the application is running but is unable to handle requests, such as when the application returns an HTTP 503 response code during restart, this application is not considered ready according to the readiness probe. If the application is not considered ready by the readiness probe, requests are not routed to that application until it is considered ready according to the readiness probe.

3.4.1. Health check concepts

In order to understand the health check pattern, you need to first understand the following concepts:

Liveness

Liveness defines whether an application is running or not. Sometimes a running application moves into an unresponsive or stopped state and needs to be restarted. Checking for liveness helps determine whether or not an application needs to be restarted.

Readiness

Readiness defines whether a running application can service requests. Sometimes a running application moves into an error or broken state where it can no longer service requests. Checking readiness helps determine whether or not requests should continue to be routed to that application.

Fail-over

Fail-over enables failures in servicing requests to be handled gracefully. If an application fails to service a request, that request and future requests can then fail-over or be routed to another application, which is usually a redundant copy of that same application.

Resilience and Stability

Resilience and Stability enable failures in servicing requests to be handled gracefully. If an application fails to service a request due to connection loss, in a resilient system that request can be retried after the connection is re-established.

Probe

A probe is a Kubernetes action that periodically performs diagnostics on a running container.

3.4.2. Viewing the booster source code and README

Prerequisites

One of the following:

  • Access to developers.redhat.com/launch

  • Fabric8 Launcher installed on a Single-node OpenShift Cluster

Procedure
  1. Use the Fabric8 Launcher tool to generate your own version of the booster.

  2. View the generated GitHub repository or download and extract the ZIP file that contains the booster source code.

3.4.3. Deploying the Health Check booster to OpenShift Online

Use one of the following options to execute the Health Check booster on OpenShift Online.

Although each method uses the same oc commands to deploy your application, using developers.redhat.com/launch provides an automated booster deployment workflow that executes the oc commands for you.

Deploying the booster using developers.redhat.com/launch
Prerequisites
Procedure
  1. Navigate to the developers.redhat.com/launch URL in a browser and log in.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on OpenShift Online using the oc command-line client, you need to authenticate the client using the token provided by the OpenShift Online web interface.

Prerequisites
Procedure
  1. Navigate to the OpenShift Online URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your OpenShift Online account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Health Check booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new OpenShift project.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Use npm to start the deployment to OpenShift.

    $ npm install && npm run openshift

    These commands install any missing module dependencies, then using the Nodeshift module, deploy the booster on OpenShift.

  5. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                             READY     STATUS      RESTARTS   AGE
    MY_APP_NAME-1-aaaaa               1/1       Running     0          58s
    MY_APP_NAME-s2i-1-build           0/1       Completed   0          2m

    The MY_APP_NAME-1-aaaaa pod should have a status of Running once its fully deployed and started. You should also wait for your pod to be ready before proceeding, which is shown in the READY column. For example, MY_APP_NAME-1-aaaaa is ready when the READY column is 1/1. Your specific pod name will vary. The number in the middle will increase with each new build. The letters at the end are generated when the pod is created.

  6. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
    MY_APP_NAME         MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME      MY_APP_NAME      8080

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the application.

3.4.4. Deploying the Health Check booster to Single-node OpenShift Cluster

Use one of the following options to execute the Health Check booster locally on Single-node OpenShift Cluster:

Although each method uses the same oc commands to deploy your application, using Fabric8 Launcher provides an automated booster deployment workflow that executes the oc commands for you.

Getting the Fabric8 Launcher tool URL and credentials

You need the Fabric8 Launcher tool URL and user credentials to create and deploy boosters on Single-node OpenShift Cluster. This information is provided when the Single-node OpenShift Cluster is started.

Prerequisites
Procedure
  1. Navigate to the console where you started Single-node OpenShift Cluster.

  2. Check the console output for the URL and user credentials you can use to access the running Fabric8 Launcher:

    Example Console Output from a Single-node OpenShift Cluster Startup
    ...
    -- Removing temporary directory ... OK
    -- Server Information ...
       OpenShift server started.
       The server is accessible via web console at:
           https://192.168.42.152:8443
    
       You are logged in as:
           User:     developer
           Password: developer
    
       To login as administrator:
           oc login -u system:admin
Deploying the booster using the Fabric8 Launcher tool
Prerequisites
Procedure
  1. Navigate to the Fabric8 Launcher URL in a browser.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on Single-node OpenShift Cluster using the oc command-line client, you need to authenticate the client using the token provided by the Single-node OpenShift Cluster web interface.

Prerequisites
Procedure
  1. Navigate to the Single-node OpenShift Cluster URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your Single-node OpenShift Cluster account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Health Check booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new OpenShift project.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Use npm to start the deployment to OpenShift.

    $ npm install && npm run openshift

    These commands install any missing module dependencies, then using the Nodeshift module, deploy the booster on OpenShift.

  5. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                             READY     STATUS      RESTARTS   AGE
    MY_APP_NAME-1-aaaaa               1/1       Running     0          58s
    MY_APP_NAME-s2i-1-build           0/1       Completed   0          2m

    The MY_APP_NAME-1-aaaaa pod should have a status of Running once its fully deployed and started. You should also wait for your pod to be ready before proceeding, which is shown in the READY column. For example, MY_APP_NAME-1-aaaaa is ready when the READY column is 1/1. Your specific pod name will vary. The number in the middle will increase with each new build. The letters at the end are generated when the pod is created.

  6. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
    MY_APP_NAME         MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME      MY_APP_NAME      8080

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the application.

3.4.5. Deploying the Health Check booster to OpenShift Container Platform

The process of creating and deploying boosters to OpenShift Container Platform is similar to OpenShift Online:

Prerequisites
Procedure

3.4.6. Interacting with the unmodified Health Check booster

Once you have the booster deployed, you will have a service called MY_APP_NAME running that exposes the following REST endpoints:

/api/greeting

Returns a JSON containing greeting of name parameter (or World as default value).

/api/stop

Forces the service to become unresponsive as means to simulate a failure.

The following steps demonstrate how to verify the service availability and simulate a failure. This failure of an available service causes the OpenShift self-healing capabilities to be trigger on the service.

Alternatively, you can use the web interface to perform these steps.

  1. Use curl to execute a GET request against the MY_APP_NAME service. You can also use a browser to do this.

    $ curl http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/greeting
    {"content":"Hello, World!"}
  2. Invoke the /api/stop endpoint and verify the availability of the /api/greeting endpoint shortly after that.

    Invoking the /api/stop endpoint simulates an internal service failure and triggers the OpenShift self-healing capabilities. When invoking /api/greeting after simulating the failure, the service should return a HTTP status 503.

    $ curl http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/stop
    Stopping HTTP server, Bye bye world !

    (followed by)

    $ curl http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME/api/greeting
    Not online
  3. Use oc get pods -w to continuously watch the self-healing capabilities in action.

    While invoking the service failure, you can watch the self-healing capabilities in action on OpenShift console, or with the oc client tools. You should see the number of pods in the READY state move to zero (0/1) and after a short period (less than one minute) move back up to one (1/1). In addition to that, the RESTARTS count increases every time you you invoke the service failure.

    $ oc get pods -w
    NAME                           READY     STATUS    RESTARTS   AGE
    MY_APP_NAME-1-26iy7   0/1       Running   5          18m
    MY_APP_NAME-1-26iy7   1/1       Running   5         19m
  4. Optional: Use the web interface to invoke the service.

    Alternatively to the interaction using the terminal window, you can use the web interface provided by the service to invoke the different methods and watch the service move through the life cycle phases.

    http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME
  5. Optional: Use the web console to view the log output generated by the application at each stage of the self-healing process.

    1. Navigate to your project.

    2. On the sidebar, click on Monitoring.

    3. In the upper right-hand corner of the screen, click on Events to display the log messages.

    4. Optional: Click View Details to display a detailed view of the Event log.

    The health check application generates the following messages:

    Message Status

    Unhealthy

    Readiness probe failed. This message is expected and indicates that the simulated failure of the /api/greeting endpoint has been detected and the self-healing process starts.

    Killing

    The unavailable Docker container running the service is being killed before being re-created.

    Pulling

    Downloading the latest version of docker image to re-create the container.

    Pulled

    Docker image downloaded successfully.

    Created

    Docker container has been successfully created

    Started

    Docker container is ready to handle requests

3.5. Circuit Breaker mission - Node.js booster

Limitation: Run this booster on a Single-node OpenShift Cluster. You can also use a manual workflow to deploy this booster to OpenShift Online Pro and OpenShift Container Platform. This booster is not currently available on OpenShift Online Starter.

Mission proficiency level: Foundational.

The Circuit Breaker mission demonstrates a generic pattern for reporting the failure of a service and then limiting access to the failed service until it becomes available to handle requests. This helps prevent cascading failure in other services that depend on the failed services for functionality.

This mission shows you how to implement a Circuit Breaker and Fallback pattern in your services.

3.5.1. The circuit breaker design pattern

The Circuit Breaker is a pattern intended to:

  • Reduce the impact of network failure and high latency on service architectures where services synchronously invoke other services.

    If one of the services:

    • becomes unavailable due to network failure, or

    • incurs unusually high latency values due to overwhelming traffic,

    other services attempting to call its endpoint may end up exhausting critical resources in an attempt to reach it, rendering themselves unusable.

  • Prevent the condition also known as cascading failure, which can render the entire microservice architecture unusable.

  • Act as a proxy between a protected function and a remote function, which monitors for failures.

  • Trip once the failures reach a certain threshold, and all further calls to the circuit breaker return an error or a predefined fallback response, without the protected call being made at all.

The Circuit Breaker usually also contain an error reporting mechanism that notifies you when the Circuit Breaker trips.

Circuit breaker implementation
  • With the Circuit Breaker pattern implemented, a service client invokes a remote service endpoint via a proxy at regular intervals.

  • If the calls to the remote service endpoint fail repeatedly and consistently, the Circuit Breaker trips, making all calls to the service fail immediately over a set timeout period and returns a predefined fallback response.

  • When the timeout period expires, a limited number of test calls are allowed to pass through to the remote service to determine whether it has healed, or remains unavailable.

    • If the test calls fail, the Circuit Breaker keeps the service unavailable and keeps returning the fallback responses to incoming calls.

    • If the test calls succeed, the Circuit Breaker closes, fully enabling traffic to reach the remote service again.

3.5.2. Circuit Breaker design tradeoffs

Table 4. Design Tradeoffs
Pros Cons
  • Enables a service to handle the failure of other services it invokes.

  • Optimizing the timeout values can be challenging

    • Larger-than-necessary timeout values may generate excessive latency.

    • Smaller-than-necessary timeout values may introduce false positives.

3.5.3. Viewing the booster source code and README

Prerequisites

One of the following:

  • Access to developers.redhat.com/launch

  • Fabric8 Launcher installed on a Single-node OpenShift Cluster

Procedure
  1. Use the Fabric8 Launcher tool to generate your own version of the booster.

  2. View the generated GitHub repository or download and extract the ZIP file that contains the booster source code.

3.5.4. Deploying the Circuit Breaker booster to OpenShift Online

Use one of the following options to execute the Circuit Breaker booster on OpenShift Online.

Although each method uses the same oc commands to deploy your application, using developers.redhat.com/launch provides an automated booster deployment workflow that executes the oc commands for you.

Deploying the booster using developers.redhat.com/launch
Prerequisites
Procedure
  1. Navigate to the developers.redhat.com/launch URL in a browser and log in.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on OpenShift Online using the oc command-line client, you need to authenticate the client using the token provided by the OpenShift Online web interface.

Prerequisites
Procedure
  1. Navigate to the OpenShift Online URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your OpenShift Online account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Circuit Breaker booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new OpenShift project.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Use the provided start-openshift.sh script to start the deployment to OpenShift.

    $ chmod +x start-openshift.sh
    $ ./start-openshift.sh

    These commands use the Nodeshift npm module to install your dependencies, launch the S2I build process on OpenShift, and start the services.

  5. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                             READY     STATUS      RESTARTS   AGE
    MY_APP_NAME-greeting-1-aaaaa     1/1       Running   0           17s
    MY_APP_NAME-greeting-1-deploy    0/1       Completed 0           22s
    MY_APP_NAME-name-1-aaaaa         1/1       Running   0           14s
    MY_APP_NAME-name-1-deploy        0/1       Completed 0           28s

    Both the MY_APP_NAME-greeting-1-aaaaa and MY_APP_NAME-name-1-aaaaa pods should have a status of Running once they are fully deployed and started. You should also wait for your pods to be ready before proceeding, which is shown in the READY column. For example, MY_APP_NAME-greeting-1-aaaaa is ready when the READY column is 1/1. Your specific pod names will vary. The number in the middle will increase with each new build. The letters at the end are generated when the pod is created.

  6. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
    MY_APP_NAME-greeting   MY_APP_NAME-greeting-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME            MY_APP_NAME-greeting   8080                    None
    MY_APP_NAME-name       MY_APP_NAME-name-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME            MY_APP_NAME-name       8080                    None

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-greeting-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the application.

3.5.5. Deploying the Circuit Breaker booster to Single-node OpenShift Cluster

Use one of the following options to execute the Circuit Breaker booster locally on Single-node OpenShift Cluster:

Although each method uses the same oc commands to deploy your application, using Fabric8 Launcher provides an automated booster deployment workflow that executes the oc commands for you.

Getting the Fabric8 Launcher tool URL and credentials

You need the Fabric8 Launcher tool URL and user credentials to create and deploy boosters on Single-node OpenShift Cluster. This information is provided when the Single-node OpenShift Cluster is started.

Prerequisites
Procedure
  1. Navigate to the console where you started Single-node OpenShift Cluster.

  2. Check the console output for the URL and user credentials you can use to access the running Fabric8 Launcher:

    Example Console Output from a Single-node OpenShift Cluster Startup
    ...
    -- Removing temporary directory ... OK
    -- Server Information ...
       OpenShift server started.
       The server is accessible via web console at:
           https://192.168.42.152:8443
    
       You are logged in as:
           User:     developer
           Password: developer
    
       To login as administrator:
           oc login -u system:admin
Deploying the booster using the Fabric8 Launcher tool
Prerequisites
Procedure
  1. Navigate to the Fabric8 Launcher URL in a browser.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on Single-node OpenShift Cluster using the oc command-line client, you need to authenticate the client using the token provided by the Single-node OpenShift Cluster web interface.

Prerequisites
Procedure
  1. Navigate to the Single-node OpenShift Cluster URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your Single-node OpenShift Cluster account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Circuit Breaker booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new OpenShift project.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Use the provided start-openshift.sh script to start the deployment to OpenShift.

    $ chmod +x start-openshift.sh
    $ ./start-openshift.sh

    These commands use the Nodeshift npm module to install your dependencies, launch the S2I build process on OpenShift, and start the services.

  5. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                             READY     STATUS      RESTARTS   AGE
    MY_APP_NAME-greeting-1-aaaaa     1/1       Running   0           17s
    MY_APP_NAME-greeting-1-deploy    0/1       Completed 0           22s
    MY_APP_NAME-name-1-aaaaa         1/1       Running   0           14s
    MY_APP_NAME-name-1-deploy        0/1       Completed 0           28s

    Both the MY_APP_NAME-greeting-1-aaaaa and MY_APP_NAME-name-1-aaaaa pods should have a status of Running once they are fully deployed and started. You should also wait for your pods to be ready before proceeding, which is shown in the READY column. For example, MY_APP_NAME-greeting-1-aaaaa is ready when the READY column is 1/1. Your specific pod names will vary. The number in the middle will increase with each new build. The letters at the end are generated when the pod is created.

  6. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
    MY_APP_NAME-greeting   MY_APP_NAME-greeting-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME            MY_APP_NAME-greeting   8080                    None
    MY_APP_NAME-name       MY_APP_NAME-name-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME            MY_APP_NAME-name       8080                    None

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-greeting-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the application.

3.5.6. Deploying the Circuit Breaker booster to OpenShift Container Platform

The process of creating and deploying boosters to OpenShift Container Platform is similar to OpenShift Online:

Prerequisites
Procedure

3.5.7. Interacting with the unmodified Node.js Circuit Breaker booster

Once you have the Node.js booster deployed, you have the following services running:

MY_APP_NAME-name

Exposes the following endpoints:

  • the /api/name endpoint, which returns a name when this service is working, and an error when this service is set up to demonstrate failure.

  • the /api/state endpoint, which controls the behavior of the /api/name endpoint and determines whether the service works correctly or demonstrates failure.

MY_APP_NAME-greeting

Exposes the following endpoints:

  • the /api/greeting endpoint that you can call to get a personalized greeting response.

    When you call the /api/greeting endpoint, it issues a call against the /api/name endpoint of the MY_APP_NAME-name service as part of processing your request. The call made against the /api/name endpoint is protected by the Circuit Breaker.

    If the remote endpoint is available, the name service responds with an HTTP code 200 (OK) and you receive the following greeting from the /api/greeting endpoint:

    {"content":"Hello, World!"}

    If the remote endpoint is unavailable, the name service responds with an HTTP code 500 (Internal server error) and you receive a predefined fallback response from the /api/greeting endpoint:

    {"content":"Hello, Fallback!"}
  • the /api/cb-state endpoint, which returns the state of the Circuit Breaker. The state can be:

    • open : the circuit breaker is preventing requests from reaching the failed service,

    • closed: the circuit breaker is allowing requests to reach the service.

The following steps demonstrate how to verify the availability of the service, simulate a failure and receive a fallback response.

  1. Use curl to execute a GET request against the MY_APP_NAME-greeting service. You can also use the Invoke button in the web interface to do this.

    $ curl http://MY_APP_NAME-greeting-MY_PROJECT_NAME.LOCAL_OPENSHIFT_HOSTNAME/api/greeting
    {"content":"Hello, World!"}
  2. To simulate the failure of the MY_APP_NAME-name service you can:

    • use the Toggle button in the web interface.

    • scale the number of replicas of the pod running the MY_APP_NAME-name service down to 0.

    • execute an HTTP PUT request against the /api/state endpoint of the MY_APP_NAME-name service to set its state to fail.

      $ curl -X PUT -H "Content-Type: application/json" -d '{"state": "fail"}' http://MY_APP_NAME-name-MY_PROJECT_NAME.LOCAL_OPENSHIFT_HOSTNAME/api/state
  3. Invoke the /api/greeting endpoint. When several requests on the /api/name endpoint fail:

    1. the Circuit Breaker opens,

    2. the state indicator in the web interface changes from CLOSED to OPEN,

    3. the Circuit Breaker issues a fallback response when you invoke the /api/greeting endpoint:

      $ curl http://MY_APP_NAME-greeting-MY_PROJECT_NAME.LOCAL_OPENSHIFT_HOSTNAME/api/greeting
      {"content":"Hello, Fallback!"}
  4. Restore the name MY_APP_NAME-name service to availability. To do this you can:

    • use the Toggle button in the web interface.

    • scale the number of replicas of the pod running the MY_APP_NAME-name service back up to 1.

    • execute an HTTP PUT request against the /api/state endpoint of the MY_APP_NAME-name service to set its state back to ok.

      $ curl -X PUT -H "Content-Type: application/json" -d '{"state": "ok"}' http://MY_APP_NAME-name-MY_PROJECT_NAME.LOCAL_OPENSHIFT_HOSTNAME/api/state
  5. Invoke the /api/greeting endpoint again. When several requests on the /api/name endpoint succeed:

    1. the Circuit Breaker closes,

    2. the state indicator in the web interface changes from OPEN to CLOSED,

    3. the Circuit Breaker issues a returns the Hello World! greeting when you invoke the /api/greeting endpoint:

      $ curl http://MY_APP_NAME-greeting-MY_PROJECT_NAME.LOCAL_OPENSHIFT_HOSTNAME/api/greeting
      {"content":"Hello, World!"}

3.5.8. Circuit breaker resources

Follow the links below for more background information on the design principles behind the Circuit Breaker pattern

3.6. Secured mission - Node.js booster

Limitation: Run this booster on a Single-node OpenShift Cluster. You can also use a manual workflow to deploy this booster to OpenShift Online Pro and OpenShift Container Platform. This booster is not currently available on OpenShift Online Starter.

Mission proficiency level: Advanced.

The Secured booster secures a REST endpoint using Red Hat SSO. (This booster expands on the REST API Level 0 booster).

Red Hat SSO:

  • Implements the Open ID Connect protocol which is an extension of the OAuth 2.0 specification.

  • Issues access tokens to provide clients with various access rights to secured resources.

Securing an application with SSO enables you to add security to your applications while centralizing the security configuration.

This mission comes with Red Hat SSO pre-configured for demonstration purposes, it does not explain its principles, usage, or configuration. Before using this mission, ensure that you are familiar with the basic concepts related to Red Hat SSO.

3.6.1. The Secured project structure

The SSO booster project contains:

  • the sources for the Greeting service, which is the one which we are going to to secure

  • a template file (service.sso.yaml) to deploy the SSO server

  • the Keycloak adapter configuration to secure the service

3.6.2. Viewing the booster source code and README

Prerequisites

One of the following:

  • Access to developers.redhat.com/launch

  • Fabric8 Launcher installed on a Single-node OpenShift Cluster

Procedure
  1. Use the Fabric8 Launcher tool to generate your own version of the booster.

  2. View the generated GitHub repository or download and extract the ZIP file that contains the booster source code.

3.6.3. Red Hat SSO deployment configuration

The service.sso.yaml file in this booster contains all OpenShift configuration items to deploy a pre-configured Red Hat SSO server. The SSO server configuration has been simplified for the sake of this exercise and does provide an out-of-the-box configuration, with pre-configured users and security settings. The service.sso.yaml file also contains very long lines, and some text editors, such as gedit, may have issues reading this file.

It is not recommended to use this SSO configuration in production. Specifically, the simplifications made to the booster security configuration impact the ability to use it in a production environment.
Table 5. SSO Booster Simplifications
Change Reason Recommendation

The default configuration includes both public and private keys in the yaml configuration files.

We did this because the end user can deploy Red Hat SSO module and have it in a usable state without needing to know the internals or how to configure Red Hat SSO.

In production, do not store private keys under source control. They should be added by the server administrator.

The configured clients accept any callback url.

To avoid having a custom configuration for each runtime, we avoid the callback verification that is required by the OAuth2 specification.

An application-specific callback URL should be provided with a valid domain name.

Clients do not require SSL/TLS and the secured applications are not exposed over HTTPS.

The boosters are simplified by not requiring certificates generated for each runtime.

In production a secure application should use HTTPS rather than plain HTTP.

The token timeout has been increased to 10 minutes from the default of 1 minute.

Provides a better user experience when working with the command line examples

From a security perspective, the window an attacker would have to guess the access token is extended. It is recommended to keep this window short as it makes it much harder for a potential attacker to guess the current token.

3.6.4. Red Hat SSO realm model

The master realm is used to secure this booster. There are two pre-configured application client definitions that provide a model for command line clients and the secured REST endpoint.

There are also two pre-configured users in the Red Hat SSO master realm that can be used to validate various authentication and authorization outcomes: admin and alice.

Red Hat SSO users

The realm model for the secured boosters includes two users:

admin

The admin user has a password of admin and is the realm administrator. This user has full access to the Red Hat SSO administration console, but none of the role mappings that are required to access the secured endpoints. You can use this user to illustrate the behavior of an authenticated, but unauthorized user.

alice

The alice user has a password of password and is the canonical application user. This user will demonstrate successful authenticated and authorized access to the secured endpoints. An example representation of the role mappings is provided in this decoded JWT bearer token:

{
  "jti": "0073cfaa-7ed6-4326-ac07-c108d34b4f82",
  "exp": 1510162193,
  "nbf": 0,
  "iat": 1510161593,
  "iss": "https://secure-sso-sso.LOCAL_OPENSHIFT_HOSTNAME/auth/realms/master", (1)
  "aud": "demoapp",
  "sub": "c0175ccb-0892-4b31-829f-dda873815fe8",
  "typ": "Bearer",
  "azp": "demoapp",
  "nonce": "90ff5d1a-ba44-45ae-a413-50b08bf4a242",
  "auth_time": 1510161591,
  "session_state": "98efb95a-b355-43d1-996b-0abcb1304352",
  "acr": "1",
  "client_session": "5962112c-2b19-461e-8aac-84ab512d2a01",
  "allowed-origins": [
    "*"
  ],
  "realm_access": {
    "roles": [ (2)
      "booster-admin"
    ]
  },
  "resource_access": { (3)
    "secured-booster-endpoint": {
      "roles": [
        "booster-admin" (4)
      ]
    },
    "account": {
      "roles": [
        "manage-account",
        "view-profile"
      ]
    }
  },
  "name": "Alice InChains",
  "preferred_username": "alice", (5)
  "given_name": "Alice",
  "family_name": "InChains",
  "email": "alice@keycloak.org"
}
1 The iss field corresponds to the Red Hat SSO realm instance URL that issues the token. This must be configured in the secured endpoint deployments in order for the token to be verified.
2 The roles object provides the roles that have been granted to the user at the global realm level. In this case alice has been granted the booster-admin role. We will see that the secured endpoint will look to the realm level for authorized roles.
3 The resource_access object contains resource specific role grants. Under this object you will find an object for each of the secured endpoints.
4 The resource_access.secured-booster-endpoint.roles object contains the roles granted to alice for the secured-booster-endpoint resource.
5 The preferred_username field provides the username that was used to generate the access token.
The application clients

The OAuth 2.0 specification allows you to define a role for application clients that access secured resources on behalf of resource owners. The master realm has the following application clients defined:

demoapp

This is a confidential type client with a client secret that is used to obtain an access token that contains grants for the alice user which enable alice to access the Thorntail, Eclipse Vert.x, Node.js and Spring Boot based REST booster deployments.

secured-booster-endpoint

The secured-booster-endpoint is a bearer-only type of client that requires a booster-admin role for accessing the associated resources, specifically the Greeting service.

3.6.5. Node.js SSO adapter configuration

The SSO adapter is the client side, or client to the SSO server, component that enforces security on the web resources. In this specific case, it is the Greeting service.

Enacting Security Example Node.js Code
const express = require(‘express’);
const Keycloak = require(‘keycloak-connect’); (1)
const kc = new Keycloak({});  (2)

const app = express();

app.use(kc.middleware());  (3)

app.use(‘/api/greeting’, kc.protect('booster-admin'), callback);  (4)
1 npm module keycloak-connect must be installed and required. The keycloak-connect module acts as connect middleware, which provides integration with express.
2 Instantiate a new Keycloak object and pass in an empty configuration object.
3 Tells express to use Keycloak as middleware.
4 Enforces that a user must be authenticated and part of the booster-admin role before accessing a resource.
Enacting Security in Keycloak Adapter using keycloak.json
{
  "realm": "master", (1)
  "resource": "secured-booster-endpoint", (2)
  "realm-public-key": "...", (3)
  "auth-server-url": "${env.SSO_AUTH_SERVER_URL}", (4)
  "ssl-required": "external",
  "disable-trust-manager": true,
  "bearer-only": true, (5)
  "use-resource-role-mappings": true
}
1 The security realm to be used.
2 The actual Keycloak client configuration.
3 PEM format of the realm public key. You can obtain this from the administration console.
4 The address of the Red Hat SSO server (Interpolation at build time).
5 If enabled the adapter will not attempt to authenticate users, but only verify bearer tokens.

The example Node.js code enables Keycloak and enforces protection of the Greeting service web resource endpoint. The keycloak.json configures the security adapter to interact with Red Hat SSO.

Additional resources

3.6.6. Deploying the Secured booster to Single-node OpenShift Cluster

Getting the Fabric8 Launcher tool URL and credentials

You need the Fabric8 Launcher tool URL and user credentials to create and deploy boosters on Single-node OpenShift Cluster. This information is provided when the Single-node OpenShift Cluster is started.

Prerequisites
Procedure
  1. Navigate to the console where you started Single-node OpenShift Cluster.

  2. Check the console output for the URL and user credentials you can use to access the running Fabric8 Launcher:

    Example Console Output from a Single-node OpenShift Cluster Startup
    ...
    -- Removing temporary directory ... OK
    -- Server Information ...
       OpenShift server started.
       The server is accessible via web console at:
           https://192.168.42.152:8443
    
       You are logged in as:
           User:     developer
           Password: developer
    
       To login as administrator:
           oc login -u system:admin
Creating the Secured booster using Fabric8 Launcher
Prerequisites
Procedure
  • Navigate to the Fabric8 Launcher URL in a browser and log in.

  • Follow the on-screen instructions to create your booster in Node.js. When asked about which deployment type, select I will build and run locally.

  • Follow on-screen instructions.

    When done, click the Download as ZIP file button and store the file on your hard drive.

Authenticating the oc CLI client

To work with boosters on Single-node OpenShift Cluster using the oc command-line client, you need to authenticate the client using the token provided by the Single-node OpenShift Cluster web interface.

Prerequisites
Procedure
  1. Navigate to the Single-node OpenShift Cluster URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your Single-node OpenShift Cluster account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Secured booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new OpenShift project.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Deploy the Red Hat SSO server using the service.sso.yaml file from your booster ZIP file:

    $ oc create -f service.sso.yaml
  5. Use npm to start the deployment to Single-node OpenShift Cluster.

    $ npm install && npm run openshift -- \
          -d SSO_AUTH_SERVER_URL=$(oc get route secure-sso -o jsonpath='{"https://"}{.spec.host}{"/auth\n"}')

    These commands install any missing module dependencies, then using the Nodeshift module, deploy the booster on OpenShift.

3.6.7. Deploying the Secured booster to OpenShift Container Platform

In addition to the Single-node OpenShift Cluster, you can create and deploy the booster on OpenShift Container Platform with only minor differences. The most important difference is that you need to create the booster application on Single-node OpenShift Cluster before you can deploy it with OpenShift Container Platform.

Prerequisites
Authenticating the oc CLI client

To work with boosters on OpenShift Container Platform using the oc command-line client, you need to authenticate the client using the token provided by the OpenShift Container Platform web interface.

Prerequisites
  • An account at OpenShift Container Platform.

Procedure
  1. Navigate to the OpenShift Container Platform URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your OpenShift Container Platform account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Secured booster using the oc CLI client
Prerequisites
  • The booster application created using the Fabric8 Launcher tool on a Single-node OpenShift Cluster.

  • The oc client authenticated. For more information, see Authenticating the oc CLI client.

Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new OpenShift project.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Deploy the Red Hat SSO server using the service.sso.yaml file from your booster ZIP file:

    $ oc create -f service.sso.yaml
  5. Use npm to start the deployment to OpenShift Container Platform.

    $ npm install && npm run openshift -- \
          -d SSO_AUTH_SERVER_URL=$(oc get route secure-sso -o jsonpath='{"https://"}{.spec.host}{"/auth\n"}')

    These commands install any missing module dependencies, then using the Nodeshift module, deploy the booster on OpenShift.

3.6.8. Authenticating to the Secured booster API endpoint

The Secured booster provides a default HTTP endpoint that accepts GET requests if the caller is authenticated and authorized. The client first authenticates against the Red Hat SSO server and then performs a GET request against the Secured booster using the access token returned by the authentication step.

Getting the Secured booster API endpoint

When using a client to interact with the booster, you must specify the Secured booster endpoint, which is the PROJECT_ID service.

Prerequisites
  • The Secured booster deployed and running.

  • The oc client authenticated.

Procedure
  1. In a terminal application, execute the oc get routes command.

    A sample output is shown in the following table:

    Example 1. List of Secured endpoints
    Name Host/Port Path Services Port Termination

    secure-sso

    secure-sso-myproject.LOCAL_OPENSHIFT_HOSTNAME

    secure-sso

    <all>

    passthrough

    PROJECT_ID

    PROJECT_ID-myproject.LOCAL_OPENSHIFT_HOSTNAME

    PROJECT_ID

    <all>

    sso

    sso-myproject.LOCAL_OPENSHIFT_HOSTNAME

    sso

    <all>

    In the above example, the booster endpoint would be http://PROJECT_ID-myproject.LOCAL_OPENSHIFT_HOSTNAME. PROJECT_ID is based on the name you entered when generating your booster using developers.redhat.com/launch or the Fabric8 Launcher tool.

Authenticating HTTP requests using the command line

Request a token by sending a HTTP POST request to the Red Hat SSO server. In the following example, the jq CLI tool is used to extract the token value from the JSON response.

Prerequisites
Procedure
  1. Request an access token with curl, the credentials, and <SSO_AUTH_SERVER_URL> and extract the token from the response with the jq command:

    curl -sk -X POST https://<SSO_AUTH_SERVER_URL>/auth/realms/master/protocol/openid-connect/token \
      -d grant_type=password \
      -d username=alice\
      -d password=password \
      -d client_id=demoapp \
      -d client_secret=1daa57a2-b60e-468b-a3ac-25bd2dc2eadc \
      | jq -r '.access_token'
    
    eyJhbGciOiJSUzI1NiIsInR5cCIgOiAiSldUIiwia2lkIiA6ICJRek1nbXhZMUhrQnpxTnR0SnkwMm5jNTNtMGNiWDQxV1hNSTU1MFo4MGVBIn0.eyJqdGkiOiI0NDA3YTliNC04YWRhLTRlMTctODQ2ZS03YjI5MjMyN2RmYTIiLCJleHAiOjE1MDc3OTM3ODcsIm5iZiI6MCwiaWF0IjoxNTA3NzkzNzI3LCJpc3MiOiJodHRwczovL3NlY3VyZS1zc28tc3NvLWRlbW8uYXBwcy5jYWZlLWJhYmUub3JnL2F1dGgvcmVhbG1zL21hc3RlciIsImF1ZCI6ImRlbW9hcHAiLCJzdWIiOiJjMDE3NWNjYi0wODkyLTRiMzEtODI5Zi1kZGE4NzM4MTVmZTgiLCJ0eXAiOiJCZWFyZXIiLCJhenAiOiJkZW1vYXBwIiwiYXV0aF90aW1lIjowLCJzZXNzaW9uX3N0YXRlIjoiMDFjOTkzNGQtNmZmOS00NWYzLWJkNWUtMTU4NDI5ZDZjNDczIiwiYWNyIjoiMSIsImNsaWVudF9zZXNzaW9uIjoiMzM3Yzk0MTYtYTdlZS00ZWUzLThjZWQtODhlODI0MGJjNTAyIiwiYWxsb3dlZC1vcmlnaW5zIjpbIioiXSwicmVhbG1fYWNjZXNzIjp7InJvbGVzIjpbImJvb3N0ZXItYWRtaW4iXX0sInJlc291cmNlX2FjY2VzcyI6eyJzZWN1cmVkLWJvb3N0ZXItZW5kcG9pbnQiOnsicm9sZXMiOlsiYm9vc3Rlci1hZG1pbiJdfSwiYWNjb3VudCI6eyJyb2xlcyI6WyJtYW5hZ2UtYWNjb3VudCIsInZpZXctcHJvZmlsZSJdfX0sIm5hbWUiOiJBbGljZSBJbkNoYWlucyIsInByZWZlcnJlZF91c2VybmFtZSI6ImFsaWNlIiwiZ2l2ZW5fbmFtZSI6IkFsaWNlIiwiZmFtaWx5X25hbWUiOiJJbkNoYWlucyIsImVtYWlsIjoiYWxpY2VAa2V5Y2xvYWsub3JnIn0.mjmZe37enHpigJv0BGuIitOj-kfMLPNwYzNd3n0Ax4Nga7KpnfytGyuPSvR4KAG8rzkfBNN9klPYdy7pJEeYlfmnFUkM4EDrZYgn4qZAznP1Wzy1RfVRdUFi0-GqFTMPb37o5HRldZZ09QljX_j3GHnoMGXRtYW9RZN4eKkYkcz9hRwgfJoTy2CuwFqeJwZYUyXifrfA-JoTr0UmSUed-0NMksGrtJjjPggUGS-qOn6OgKcmN2vaVAQlxW32y53JqUXctfLQ6DhJzIMYTmOflIPy0sgG1mG7sovQhw1xTg0vTjdx8zQ-EJcexkj7IivRevRZsslKgqRFWs67jQAFQA

    <SSO_AUTH_SERVER_URL> is the url of the secure-sso service.

    The attributes, such as username, password, and client_secret are usually kept secret, but the above command uses the default provided credentials with this booster for demonstration purpose.

    If you do not want to use jq to extract the token, you can run just the curl command and manually extract the access token.

    The -sk option tells curl to ignore failures resulting from self-signed certificates. Do not use this option in a production environment. On macOS, you must have curl version 7.56.1 or greater installed. It must also be built with OpenSSL.
  1. Invoke the Secured service. Attach the access (bearer) token to the HTTP headers:

    $ curl -v -H "Authorization: Bearer <TOKEN>" http://<SERVICE_HOST>/api/greeting
    
    {
        "content": "Hello, World!",
        "id": 2
    }
    Example 2. A sample GET Request Headers with an Access (Bearer) Token
    > GET /api/greeting HTTP/1.1
    > Host: <SERVICE_HOST>
    > User-Agent: curl/7.51.0
    > Accept: */*
    > Authorization: Bearer <TOKEN>

    <SERVICE_HOST> is the URL of the secured booster endpoint. For more information, see Getting the Secured booster API endpoint.

  2. Verify the signature of the access token.

    The access token is a JSON Web Token, so you can decode it using the JWT Debugger:

    1. In a web browser, navigate to the JWT Debugger website.

    2. Select RS256 from the Algorithm drop down menu.

      Make sure the web form has been updated after you made the selection, so it displays the correct RSASHA256(…​) information in the Signature section. If it has not, try switching to HS256 and then back to RS256.
    3. Paste the following content in the topmost text box into the VERIFY SIGNATURE section:

      -----BEGIN PUBLIC KEY-----
      MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAoETnPmN55xBJjRzN/cs30OzJ9olkteLVNRjzdTxFOyRtS2ovDfzdhhO9XzUcTMbIsCOAZtSt8K+6yvBXypOSYvI75EUdypmkcK1KoptqY5KEBQ1KwhWuP7IWQ0fshUwD6jI1QWDfGxfM/h34FvEn/0tJ71xN2P8TI2YanwuDZgosdobx/PAvlGREBGuk4BgmexTOkAdnFxIUQcCkiEZ2C41uCrxiS4CEe5OX91aK9HKZV4ZJX6vnqMHmdDnsMdO+UFtxOBYZio+a1jP4W3d7J5fGeiOaXjQCOpivKnP2yU2DPdWmDMyVb67l8DRA+jh0OJFKZ5H2fNgE3II59vdsRwIDAQAB
      -----END PUBLIC KEY-----
      This is the master realm public key from the Red Hat SSO server deployment of the Secured booster.
    4. Paste the token output from the client output into the Encoded box.

      The Signature Verified sign is displayed on the debugger page.

Authenticating HTTP requests using the web interface

In addition to the HTTP API, the secured endpoint also contains a web interface to interact with.

The following procedure is an exercise for you to see how security is enforced, how you authenticate, and how you work with the authentication token.

Prerequisites
Procedure
  1. In a web browser, navigate to the endpoint URL.

  2. Perform an unauthenticated request:

    1. Click the Invoke button.

      sso main
      Figure 1. Unauthenticated Secured Booster Web Interface

      The services responds with an HTTP 403 Forbidden status code.

      This is not the correct status code. It should be HTTP 401 Unauthorized. This issue has been identified and this booster will be updated as soon as it is resolved.
  3. Perform an authenticated request as a user:

    1. Click the Login button to authenticate against Red Hat SSO. You will be redirected to the SSO server.

    2. Log in as the Alice user. You will be redirected back to the web interface.

      You can see the access (bearer) token in the command line output at the bottom of the page.
      sso alice
      Figure 2. Authenticated Secured Booster Web Interface (as Alice)
    3. Click Invoke again to access the Greeting service.

      Confirm that there is no exception and the JSON response payload is displayed. This means the service accepted your access (bearer) token and you are authorized access to the Greeting service.

      sso invoke alice
      Figure 3. The Result of an Authenticated Greeting Request (as Alice)
    4. Log out.

  4. Perform an authenticated request as an admininstrator:

    1. Click the Invoke button.

      Confirm that this sends an unauthenticated request to the Greeting service.

    2. Click the Login button and log in as the admin user.

      sso admin
      Figure 4. Authenticated Secured Booster Web Interface (as admin)
  5. Click the Invoke button.

    The service responds with an HTTP 403 Forbidden status code because the admin user is not authorized to access the Greeting service.

    sso unauthorized
    Figure 5. Unauthorized Error Message

3.6.9. Secured SSO resources

Follow the links below for additional information on the principles behind the OAuth2 specification and on securing your applications using Red Hat SSO and Keycloak:

3.7. Cache mission - Node.js booster

Limitation: Run this booster on a Single-node OpenShift Cluster. You can also use a manual workflow to deploy this booster to OpenShift Online Pro and OpenShift Container Platform. This booster is not currently available on OpenShift Online Starter.

Mission proficiency level: Advanced.

The Cache mission demonstrates how to use a cache to increase the response time of applications.

This mission shows you how to:

  • Deploy a cache to OpenShift.

  • Use a cache within an application.

3.7.1. How caching works and when you need it

Caches allows you to store information and access it for a given period of time. You can access information in a cache faster or more reliably than repeatedly calling the original service. A disadvantage of using a cache is that the cached information is not up to date. However, that problem can be reduced by setting an expiration or TTL (time to live) on each value stored in the cache.

Example 3. Caching example

Assume you have two applications: service1 and service2:

  • Service1 depends on a value from service2.

    • If the value from service2 infrequently changes, service1 could cache the value from service2 for a period of time.

    • Using cached values can also reduce the number of times service2 is called.

  • If it takes service1 500 ms to retrieve the value directly from service2, but 100 ms to retrieve the cached value, service1 would save 400 ms by using the cached value for each cached call.

  • If service1 would make uncached calls to service2 5 times per second, over 10 seconds, that would be 50 calls.

  • If service1 started using a cached value with a TTL of 1 second instead, that would be reduced to 10 calls over 10 seconds.

How the Cache mission works
  1. The cache, cute name, and greeting services are deployed and exposed.

  2. User accesses the web frontend of the greeting service.

  3. User invokes the greeting HTTP API using a button on the web frontend.

  4. The greeting service depends on a value from the cute name service.

    • The greeting service first checks if that value is stored in the cache service. If it is, then the cached value is returned.

    • If the value is not cached, the greeting service calls the cute name service, returns the value, and stores the value in the cache service with a TTL of 5 seconds.

  5. The web front end displays the response from the greeting service as well as the total time of the operation.

  6. User invokes the service multiple times to see the difference between cached and uncached operations.

    • Cached operations are significantly faster than uncached operations.

    • User can force the cache to be cleared before the TTL expires.

3.7.2. Viewing the booster source code and README

Prerequisites

One of the following:

  • Access to developers.redhat.com/launch

  • Fabric8 Launcher installed on a Single-node OpenShift Cluster

Procedure
  1. Use the Fabric8 Launcher tool to generate your own version of the booster.

  2. View the generated GitHub repository or download and extract the ZIP file that contains the booster source code.

3.7.3. Deploying the Cache booster to OpenShift Online

Use one of the following options to execute the Cache booster on OpenShift Online.

Although each method uses the same oc commands to deploy your application, using developers.redhat.com/launch provides an automated booster deployment workflow that executes the oc commands for you.

Deploying the booster using developers.redhat.com/launch
Prerequisites
Procedure
  1. Navigate to the developers.redhat.com/launch URL in a browser and log in.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on OpenShift Online using the oc command-line client, you need to authenticate the client using the token provided by the OpenShift Online web interface.

Prerequisites
Procedure
  1. Navigate to the OpenShift Online URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your OpenShift Online account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Cache booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new project.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Deploy the cache service.

    $ oc apply -f service.cache.yml
  5. Use start-openshift.sh to start the deployment to OpenShift.

    $ ./start-openshift.sh
  6. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                             READY     STATUS      RESTARTS   AGE
    cache-server-123456789-aaaaa             1/1       Running     0          8m
    MY_APP_NAME-cutename-1-bbbbb       1/1       Running     0          4m
    MY_APP_NAME-cutename-s2i-1-build   0/1       Completed   0          7m
    MY_APP_NAME-greeting-1-ccccc       1/1       Running     0          3m
    MY_APP_NAME-greeting-s2i-1-build   0/1       Completed   0          3m

    Your 3 pods should have a status of Running once they are fully deployed and started.

  7. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
    MY_APP_NAME-cutename   MY_APP_NAME-cutename-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME             MY_APP_NAME-cutename   8080                    None
    MY_APP_NAME-greeting   MY_APP_NAME-greeting-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME             MY_APP_NAME-greeting   8080                    None

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-greeting-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the greeting service.

3.7.4. Deploying the Cache booster to Single-node OpenShift Cluster

Use one of the following options to execute the Cache booster locally on Single-node OpenShift Cluster:

Although each method uses the same oc commands to deploy your application, using Fabric8 Launcher provides an automated booster deployment workflow that executes the oc commands for you.

Getting the Fabric8 Launcher tool URL and credentials

You need the Fabric8 Launcher tool URL and user credentials to create and deploy boosters on Single-node OpenShift Cluster. This information is provided when the Single-node OpenShift Cluster is started.

Prerequisites
Procedure
  1. Navigate to the console where you started Single-node OpenShift Cluster.

  2. Check the console output for the URL and user credentials you can use to access the running Fabric8 Launcher:

    Example Console Output from a Single-node OpenShift Cluster Startup
    ...
    -- Removing temporary directory ... OK
    -- Server Information ...
       OpenShift server started.
       The server is accessible via web console at:
           https://192.168.42.152:8443
    
       You are logged in as:
           User:     developer
           Password: developer
    
       To login as administrator:
           oc login -u system:admin
Deploying the booster using the Fabric8 Launcher tool
Prerequisites
Procedure
  1. Navigate to the Fabric8 Launcher URL in a browser.

  2. Follow on-screen instructions to create and launch your booster in Node.js.

Authenticating the oc CLI client

To work with boosters on Single-node OpenShift Cluster using the oc command-line client, you need to authenticate the client using the token provided by the Single-node OpenShift Cluster web interface.

Prerequisites
Procedure
  1. Navigate to the Single-node OpenShift Cluster URL in a browser.

  2. Click on the question mark icon in the top right-hand corner of the Web console, next to your user name.

  3. Select Command Line Tools in the drop-down menu.

  4. Find the text box that contains the oc login …​ command with the hidden token, and click the button next to it to copy its content to your clipboard.

  5. Paste the command into a terminal application. The command uses your authentication token to authenticate your oc CLI client with your Single-node OpenShift Cluster account.

    $ oc login OPENSHIFT_URL --token=MYTOKEN
Deploying the Cache booster using the oc CLI client
Prerequisites
Procedure
  1. Clone your project from GitHub.

    $ git clone git@github.com:USERNAME/MY_PROJECT_NAME.git

    Alternatively, if you downloaded a ZIP file of your project, extract it.

    $ unzip MY_PROJECT_NAME.zip
  2. Create a new project.

    $ oc new-project MY_PROJECT_NAME
  3. Navigate to the root directory of your booster.

  4. Deploy the cache service.

    $ oc apply -f service.cache.yml
  5. Use start-openshift.sh to start the deployment to OpenShift.

    $ ./start-openshift.sh
  6. Check the status of your booster and ensure your pod is running.

    $ oc get pods -w
    NAME                             READY     STATUS      RESTARTS   AGE
    cache-server-123456789-aaaaa             1/1       Running     0          8m
    MY_APP_NAME-cutename-1-bbbbb       1/1       Running     0          4m
    MY_APP_NAME-cutename-s2i-1-build   0/1       Completed   0          7m
    MY_APP_NAME-greeting-1-ccccc       1/1       Running     0          3m
    MY_APP_NAME-greeting-s2i-1-build   0/1       Completed   0          3m

    Your 3 pods should have a status of Running once they are fully deployed and started.

  7. Once your booster is deployed and started, determine its route.

    Example Route Information
    $ oc get routes
    NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
    MY_APP_NAME-cutename   MY_APP_NAME-cutename-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME             MY_APP_NAME-cutename   8080                    None
    MY_APP_NAME-greeting   MY_APP_NAME-greeting-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME             MY_APP_NAME-greeting   8080                    None

    The route information of a pod gives you the base URL which you use to access it. In the example above, you would use http://MY_APP_NAME-greeting-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME as the base URL to access the greeting service.

3.7.5. Deploying the Cache booster to OpenShift Container Platform

The process of creating and deploying boosters to OpenShift Container Platform is similar to OpenShift Online:

Prerequisites
Procedure

3.7.6. Interacting with the unmodified Cache booster

Prerequisites
  • Your application deployed

Procedure
  1. Navigate to the greeting service using your browser.

  2. Click Invoke the service once.

    Notice the duration value is above 2000. Also notice the cache state has changed form No cached value to A value is cached.

  3. Wait 5 seconds and notice cache state has changed back to No cached value.

    The TTL for the cached value is set to 5 seconds. When the TTL expires, the value is no longer cached.

  4. Click Invoke the service once more to cache the value.

  5. Click Invoke the service a few more times over the course of a few seconds while cache state is A value is cached.

    Notice a significantly lower duration value since it is using a cached value. If you click Clear the cache, the cache is emptied.

3.7.7. Caching resources

More background and related information on caching can be found here:

4. Debugging

This section contains information about debugging your Node.js–based application and using debug logging in both local and remote deployments.

4.1. Remote debugging

To remotely debug an application, you need to start it in a debugging mode and attach a debugger to it.

4.1.1. Starting your application locally and attaching the native debugger

The native debugger enables you to debug your Node.js–based application using the built-in debugging client.

Prerequisites
  • An application you want to debug.

Procedure
  1. Start the application with the debugger enabled.

    The native debugger is automatically attached and provides a debugging prompt.

    Example application with the debugger enabled
    $ node inspect app.js
    < Debugger listening on ws://127.0.0.1:9229/12345678-aaaa-bbbb-cccc-0123456789ab
    < For help see https://nodejs.org/en/docs/inspector
    < Debugger attached.
    ...
    debug>

    If you have a different entry point for your application, you need to change the command to specify that entry point:

    $ node inspect path/to/entrypoint

    For example, when using the express generator to create your application, the entry point is set to ./bin/www by default. Some of the boosters, such as the REST API Level 0 booster, use ./bin/www as an entry point.

  2. Use the debugger prompt to perform debugging commands.

4.1.2. Starting your application locally and attaching the V8 inspector

The V8 inspector enables you to debug your Node.js–based application using other tools, such as Chrome DevTools, that use the Chrome Debugging Protocol.

Prerequisites
Procedure
  1. Start your application with the V8 inspector integration enabled.

    $ node --inspect app.js

    If you have a different entry point for your application, you need to change the command to specify that entry point:

    $ node --inspect path/to/entrypoint

    For example, when using the express generator to create your application, the entry point is set to ./bin/www by default. Some of the boosters, such as the REST API Level 0 booster, use ./bin/www as an entry point.

  2. Attach the V8 inspector and perform debugging commands.

    For example, if using Google Chrome:

    1. Navigate to chrome://inspect.

    2. Select your application from below Remote Target.

    3. You can now see the source of your application and can perform debugging actions.

4.1.3. Starting your application on OpenShift in debugging mode

To debug your Node.js-based application on OpenShift remotely, you must set the NODE_ENV environment variable inside the container to development and configure port forwarding so that you can connect to your application from a remote debugger.

Prerequisites
  • Your application running on OpenShift.

  • The oc binary installed on your machine.

  • The ability to execute the oc port-forward command in your target OpenShift environment.

Procedure
  1. Using the oc command, list the available deployment configurations:

    $ oc get dc
  2. Set the NODE_ENV environment variable in the deployment configuration of your application to development to enable debugging. For example:

    $ oc set env dc/MY_APP_NAME NODE_ENV=development
  3. Redeploy the application if it is not set to redeploy automatically on configuration change. For example:

    $ oc rollout latest dc/MY_APP_NAME
  4. Configure port forwarding from your local machine to the application pod:

    1. List the currently running pods and find one containing your application:

      $ oc get pod
      NAME                            READY     STATUS      RESTARTS   AGE
      MY_APP_NAME-3-1xrsp          0/1       Running     0          6s
      ...
    2. Configure port forwarding:

      $ oc port-forward MY_APP_NAME-3-1xrsp $LOCAL_PORT_NUMBER:5858

      Here, $LOCAL_PORT_NUMBER is an unused port number of your choice on your local machine. Remember this number for the remote debugger configuration.

  5. Attach the V8 inspector and perform debugging commands.

    For example, if using Google Chrome:

    1. Navigate to chrome://inspect.

    2. Click Configure.

    3. Add 127.0.0.1:$LOCAL_PORT_NUMBER.

    4. Click Done.

    5. Select your application from below Remote Target.

    6. You can now see the source of your application and can perform debugging actions.

  6. When you are done debugging, unset the NODE_ENV environment variable in your application pod. For example:

    $ oc set env dc/MY_APP_NAME NODE_ENV-

4.2. Debug logging

Debug logging is a way to add detailed information to the application log when debugging. This allows you to:

  • Keep minimal logging output during normal operation of the application for improved readability and reduced disk space usage.

  • View detailed information about the inner workings of the application when resolving issues.

4.2.1. Add debug logging

This example uses the debug package, but there are also other packages available that can handle debug logging.

Prerequisites
  • An application you want to debug. For example, a booster.

Procedure
  1. Add the debug logging definition.

    const debug = require('debug')('mybooster');
  2. Add debug statements.

    app.use('/api/greeting', (request, response) => {
      const name = request.query ? request.query.name : undefined;
      //log name in debugging
      debug('name: '+name);
      response.send({content: `Hello, ${name || 'World'}`});
    });
  3. Add the debug module to package.json.

    ...
    "dependencies": {
        "debug": "^3.1.0"
      }

    Depending on your application, this module may already be included. For example, when using the express generator to create your application, the debug module is already added to package.json. Some of the boosters, such as the REST API Level 0 booster, already have the debug module in the package.json.

  4. Install the application dependencies.

    $ npm install

4.2.2. Accessing debug logs on localhost

Use the DEBUG environment variable when starting your application to enable debug logging.

Prerequisites
  • An application with debug logging.

Procedure
  1. Set the DEBUG environment variable when starting your application to enable debug logging.

    $ DEBUG=mybooster npm start

    The debug module can use wildcards to filter debugging messages. This is set using the DEBUG environment variable.

  2. Test your application to invoke debug logging.

    For example, when debug logging in the REST API Level 0 booster is set to log the name variable in the /api/greeting method:

    $ curl http://localhost:8080/api/greeting?name=Sarah
  3. View your application logs to see your debug messages.

    mybooster name: Sarah +3m

4.2.3. Accessing Node.js debug logs on OpenShift

Use the the DEBUG environment variable in your application pod in OpenShift to enable debug logging.

Prerequisites
  • An application with debug logging.

  • The oc CLI client installed.

Procedure
  1. Use the oc CLI client to log into your OpenShift instance.

    $ oc login ...
  2. Deploy your application to OpenShift.

    $ npm run openshift

    This runs the openshift npm script, which wraps direct calls to nodeshift.

  3. Find the name of your pod and follow the logs to watch it start.

    $ oc get pods
    ....
    $ oc logs -f pod/POD_NAME
    After your pod has started, leave this command running and execute the remaining steps in a new terminal window. This allows you to follow the logs and see new entries made to it.
  4. Test your application.

    For example, if you had debug logging in the REST API Level 0 booster to log the name variable in the /api/greeting method:

    $ oc get routes
    ...
    $ curl $APPLICATION_ROUTE/api/greeting?name=Sarah
  5. Return to your pod logs and notice there are no debug logging messages in the logs.

  6. Set the DEBUG environment variable to enable debug logging.

    $ oc get dc
    ...
    $ oc set env dc DC_NAME DEBUG=mybooster
  7. Return to your pod logs to watch the update roll out.

    After the update has rolled out, your pod will stop and you will no longer be following the logs.

  8. Find the name of your new pod and follow the logs.

    $ oc get pods
    ....
    $ oc logs -f pod/POD_NAME
    After your pod has started, leave this command running and execute the remaining steps in a different terminal window. This allows you to follow the logs and see new entries made to it. Specifically, the logs will show your debug messages.
  9. Test the application to invoke debug logging.

    $ oc get routes
    ...
    $ curl $APPLICATION_ROUTE/api/greeting?name=Sarah
  10. Return to your pod logs to see the debug messages.

    ...
    mybooster name: Sarah +3m

To disable debug logging, remove the DEBUG environment variable from the pod:

$ oc set env dc DC_NAME DEBUG-
Additional resources

More details on environment variables are available in the OpenShift documentation.

5. Monitoring your application

5.1. Application metrics

5.1.1. Exposing application metrics using Prometheus on Node.js

In this example, you:

  • Configure your application to expose metrics.

  • Collect and view the data using Prometheus.

Note that Prometheus actively connects to a monitored application to collect data; the application does not actively send metrics to a server.

Prerequisites
  • Prometheus configured to collect metrics from the application:

    1. Download and extract the archive with the latest Prometheus release:

      $ wget https://github.com/prometheus/prometheus/releases/download/v2.4.3/prometheus-2.4.3.linux-amd64.tar.gz
      $ tar -xvf  prometheus-2.4.3.linux-amd64.tar.gz
    2. Navigate to the directory with Prometheus:

      $ cd  prometheus-2.4.3.linux-amd64
    3. Append the following snippet to the prometheus.yml file to specify the port where your application exposes the metrics endpoint:

        - job_name: nodejs
           static_configs:
           - targets: ['localhost:8888']

      The default behavior of Node.js-based applications is to expose metrics at the /metrics endpoint. This is also what Prometheus expects.

  • The Prometheus server started on localhost:

    Start Prometheus and wait until the Server is ready to receive web requests message is displayed in the console.

    $ ./prometheus
  • The prom-client npm package installed:

    $ npm install prom-client express body-parser --save
Procedure
  1. Create an example {NodeJS} application and save it in a file named app.js:

    'use strict';
    const path = require('path');
    const express = require('express');
    const bodyParser = require('body-parser');
    const client = require('prom-client');
    
    // enable prom-client to expose default application metrics
    const collectDefaultMetrics = client.collectDefaultMetrics;
    
    // define a custom prefix string for application metrics
    collectDefaultMetrics({ prefix: 'application:' });
    
    const histogram = new client.Histogram({
      name: 'application:hello',
      help: 'Duration of HTTP requests in ms',
      labelNames: ['status_code'],
      buckets: [0.1, 5, 15, 50, 100, 500]
    });
    const app = express();
    const port = 8888;
    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({extended: false}));
    app.use('/api/greeting', (request, response) => {
      const end = histogram.startTimer();
      const name = request.query ? request.query.name : undefined;
      response.send({content: `Hello, ${name || 'World!'}`});
      end();
    });
    
    app.get('/metrics', (req, res) => {
      res.set('Content-Type', client.register.contentType);
      res.end(client.register.metrics());
    })
    
    app.listen(port, () => console.log(`Example app listening on port ${parameter-port}!`))
  2. Start your application:

    $ node app.js
  3. Invoke the traced endpoint several times:

    $ curl http://localhost:8888/api/greeting
    {"content":"Hello, World!"}
  4. Wait at least 15 seconds for the collection to happen, and view the metrics in the Prometheus web UI:

    1. Open the Prometheus UI at http://localhost:9090/ and type hello into the Expression box.

    2. From the suggestions, select for example application:hello_count and click the Execute button. Note that all metrics you created are prefixed with application:.

    3. In the table below, you can see the number of times you invoked the resource method.

    4. Alternatively, select application:hello_time_mean_seconds to see the mean time of all the invocations.

Additional resources

6. Developing an application for the Node.js runtime

6.1. Node.js runtime API

The Node.js runtime provides the core Node.js API which is documented in the Node.js API documentation.

6.2. Creating a Node.js application

In addition to using a booster, you can also create new Node.js applications from scratch and deploy them to OpenShift.

6.2.1. Creating an application

Prerequisites
  • npm installed.

Procedure
  1. Create the application folder.

    $ mkdir myApp
  2. Initialize your application with npm.

    The rest of this example assumes the entry point is app.js, which you are prompted to set when running npm init.

    $ cd myApp
    $ npm init
  3. Create the entry point in a new file called app.js.

    Example app.js
    const http = require('http');
    
    const server = http.createServer((request, response) => {
      response.statusCode = 200;
      response.setHeader('Content-Type', 'application/json');
    
      const greeting = {content: 'Hello, World!'};
    
      response.write(JSON.stringify(greeting));
      response.end();
    });
    
    server.listen(8080, () => {
      console.log('Server running at http://localhost:8080');
    });
  4. Start your application.

    $ node app.js
    Server running at http://localhost:8080
  5. Using curl or your browser, verify your application is running at http://localhost:8080.

    $ curl http://localhost:8080
    {"content":"Hello, World!"}

6.2.2. Deploying an application to OpenShift

Prerequisites
  • The oc CLI client installed.

  • npm installed.

Procedure
  1. Add nodeshift to your application.

    $ npm install nodeshift --save
  2. Add the openshift and start entries to the scripts section in package.json.

    {
      "name": "myApp",
      "version": "1.0.0",
      "description": "",
      "main": "app.js",
      "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1",
        "openshift": "nodeshift --strictSSL=false --metadata.out=deployment-metadata.json --build.forcePull=true --dockerImage=registry.access.redhat.com/rhoar-nodejs/nodejs-8",
        "start": "node app.js",
        ...
      }
      ...
    }

    The openshift script uses nodeshift to deploy the application to OpenShift.

  3. Optional: Add a files section in package.json.

    {
      "name": "myApp",
      "version": "1.0.0",
      "description": "",
      "main": "app.js",
      "scripts": {
        ...
      },
      "files": [
        "package.json",
        "app.js"
      ]
      ...
    }

    The files section tells nodeshift what files and directories to include when deploying to OpenShift. nodeshift uses the node-tar module to create a tar file based on the files and directories you list in the files section. This tar file is used when nodeshift deploys your application to OpenShift. If the files section is not specified, nodeshift will send the entire current directory, excluding:

    • node_modules/

    • .git/

    • tmp/

      It is recommended that you include a files section in package.json to avoid including unnecessary files when deploying to OpenShift.

  4. Log in to your OpenShift instance with the oc client.

    $ oc login ...
  5. Use nodeshift to deploy the application to OpenShift.

    $ npm run openshift
  6. Expose the application in OpenShift using a route.

    Example for exposing a service using a route
    $ oc expose service myapp

Optionally, you can create a .nodeshift directory at the root of your project to include deployment yaml files. These files will create items such as routes when deploying your application to OpenShift using nodeshift. For example, to add a route during deployment, you could create a .nodeshift/route.yaml with the following:

Example .nodeshift/route.yaml
apiVersion: v1
kind: Route
metadata:
  name: myapp
spec:
  port:
    targetPort: 8080
  to:
    kind: Service
    name: myapp

6.3. Deploying an existing Node.js application to OpenShift

You can deploy an existing Node.js application to OpenShift using the steps in Deploying an application to OpenShift.

In addition, you must verify the following items when deploying an existing application:

  • Ensure the files section of package.json lists all files and directories you need to deploy with your application.

  • Ensure the start entry in the scripts section of package.json correctly starts your application.

  • Ensure all the ports used by your application are correctly exposed when configuring your routes.

Appendix A: About Nodeshift

Nodeshift is a module for running OpenShift deployments with Node.js projects.

Nodeshift assumes you have the oc CLI client installed, and you are logged into your OpenShift cluster. Nodeshift also uses the current project the oc CLI client is using.

Nodeshift uses resource files in the .nodeshift folder located at the root of the project to handle creating OpenShift Routes, Services and DeploymentConfigs. More details on Nodeshift are available on the Nodeshift project page.

Appendix B: Updating the deployment configuration of a booster

The deployment configuration for a booster contains information related to deploying and running the booster in OpenShift, such as route information or readiness probe location. The deployment configuration of a booster is stored in a set of YAML files. For boosters that use the Fabric8 Maven Plugin, the YAML files are located in the src/main/fabric8/ directory. For boosters using Nodeshift, the YAML files are located in the .nodeshift directory.

The deployment configuration files used by the Fabric8 Maven Plugin and Nodeshift do not have to be full OpenShift resource definitions. Both Fabric8 Maven Plugin and Nodeshift can take the deployment configuration files and add some missing information to create a full OpenShift resource definition. The resource definitions generated by the Fabric8 Maven Plugin are available in the target/classes/META-INF/fabric8/ directory. The resource definitions generated by Nodeshift are available in the tmp/nodeshift/resource/ directory.

Prerequisites
  • An existing booster project.

  • The oc CLI client installed.

Procedure
  1. Edit an existing YAML file or create an additional YAML file with your configuration update.

    • For example, if your booster already has a YAML file with a readinessProbe configured, you could change the path value to a different available path to check for readiness:

      spec:
        template:
          spec:
            containers:
              readinessProbe:
                httpGet:
                  path: /path/to/probe
                  port: 8080
                  scheme: HTTP
      ...
    • If a readinessProbe is not configured in an existing YAML file, you can also create a new YAML file in the same directory with the readinessProbe configuration.

  2. Deploy the updated version of your booster using Maven or npm.

  3. Verify that your configuration updates show in the deployed version of your booster.

    $ oc export all --as-template='my-template'
    
    apiVersion: v1
    kind: Template
    metadata:
      creationTimestamp: null
      name: my-template
    objects:
    - apiVersion: v1
      kind: DeploymentConfig
      ...
      spec:
        ...
        template:
          ...
          spec:
            containers:
              ...
              livenessProbe:
                failureThreshold: 3
                httpGet:
                  path: /path/to/different/probe
                  port: 8080
                  scheme: HTTP
                initialDelaySeconds: 60
                periodSeconds: 30
                successThreshold: 1
                timeoutSeconds: 1
              ...
Additional resources

If you updated the configuration of your application directly using the web-based console or the oc CLI client, export and add these changes to your YAML file. Use the oc export all command to show the configuration of your deployed application.

Appendix C: Configuring a Jenkins freestyle project to deploy your Node.js application with nodeshift

Similar to using nodeshift from your local host to deploy a Node.js application, you can configure Jenkins to use nodeshift to deploy a Node.js application.

Prerequisites
  • Access to an OpenShift cluster.

  • The Jenkins container image running on same OpenShift cluster.

  • The Node.js plugin installed on your Jenkins server.

  • A Node.js application configured to use nodeshift and the Red Hat base image.

    Example using the Red Hat base image with nodeshift
    $ nodeshift --dockerImage=registry.access.redhat.com/rhoar-nodejs/nodejs-8 ...
  • The source of the application available in GitHub.

Procedure
  1. Create a new OpenShift project for your application:

    1. Open the OpenShift Web console and log in.

    2. Click Create Project to create a new OpenShift project.

    3. Enter the project information and click Create.

  2. Ensure Jenkins has access to that project.

    For example, if you configured a service account for Jenkins, ensure that account has edit access to the project of your application.

  3. Create a new freestyle Jenkins project on your Jenkins server:

    1. Click New Item.

    2. Enter a name, choose Freestyle project, and click OK.

    3. Under Source Code Management, choose Git and add the GitHub url of your application.

    4. Under Build Environment, make sure Provide Node & npm bin/ folder to PATH is checked and the Node.js environment is configured.

    5. Under Build, choose Add build step and select Execute Shell.

    6. Add the following to the Command area:

      npm install -g nodeshift
      nodeshift --strictSSL=false --dockerImage=registry.access.redhat.com/rhoar-nodejs/nodejs-8 --namespace=MY_PROJECT

      Substitute MY_PROJECT with the name of the OpenShift project for your application.

    7. Click Save.

  4. Click Build Now from the main page of the Jenkins project to verify your application builds and deploys to the OpenShift project for your application.

    You can also verify that your application is deployed by opening the route in the OpenShift project of the application.

Next steps

  • Consider adding GITSCM polling or using the Poll SCM build trigger. These options enable builds to run every time a new commit is pushed to the GitHub repository.

  • Consider adding nodeshift as a global package when configuring the Node.js plugin. This allows you to omit npm install -g nodeshift when adding your Execute Shell build step.

  • Consider adding a build step that executes tests before deploying.

Appendix D: Breakdown of package.json properties

{
  "name": "nodejs-rest-http",
  "version": "1.1.1",
  "author": "Red Hat, Inc.",
  "license": "Apache-2.0",
  "scripts": {
    "test": "tape test/*.js | tap-spec", (1)
    "lint": "eslint test/*.js app.js bin/*",
    "prepare": "nsp check",
    "coverage": "nyc npm test",
    "coveralls": "nyc npm test && nyc report --reporter=text-lcov | coveralls",
    "ci": "npm run lint && npm run coveralls",
    "dependencyCheck": "szero . --ci",
    "release": "standard-version",
    "openshift": "nodeshift --strictSSL=false --nodeVersion=8.x", (2)
    "postinstall": "license-reporter report && license-reporter save --xml licenses.xml",
    "start": "node ." (3)
  },
  "main": "./bin/www", (4)
  "repository": {
    "type": "git",
    "url": "git://github.com/nodeshift-starters/nodejs-rest-http.git"
  },
  "files": [ (5)
    "package.json",
    "app.js",
    "public",
    "bin",
    "LICENSE",
    "licenses"
  ],
  "bugs": {
    "url": "https://github.com/nodeshift-starters/nodejs-rest-http/issues"
  },
  "homepage": "https://github.com/nodeshift-starters/nodejs-rest-http",
  "devDependencies": { (6)
    "coveralls": "^3.0.0",
    "nodeshift": "^1.3.0",
    "nsp": "~3.1.0",
    "nyc": "~11.4.1",
    "standard-version": "^4.2.0",
    "supertest": "^3.0.0",
    "szero": "^1.0.0",
    "tap-spec": "~4.1.1",
    "tape": "~4.8.0",
    "xo": "~0.20.3"
  },
  "dependencies": { (7)
    "body-parser": "^1.18.2",
    "debug": "^3.1.0",
    "express": "^4.16.0",
    "license-reporter": "^1.1.3"
  }
}
1 A npm script for running unit tests. Run with npm run test.
2 A npm script for deploying this application to Single-node OpenShift Cluster. Run with npm run openshift. The strictSSL option allows us to deploy to Single-node OpenShift Cluster instances with self-signed certificates.
3 A npm script for starting this application. Run with npm start.
4 The primary entrypoint for the application when run with npm start.
5 Specifies the files to be included in the binary that is uploaded to Single-node OpenShift Cluster.
6 A list of development dependencies to be installed from the npm registry. These are used for testing and deployment to Single-node OpenShift Cluster.
7 A list of dependencies to be installed from the npm registry.

Appendix E: Additional Node.js resources

Appendix F: Application development resources

For additional information on application development with OpenShift see:

Appendix G: The Source-to-Image (S2I) build process

Source-to-Image (S2I) is a build tool for generating reproducible Docker-formatted container images from online SCM repositories with application sources. With S2I builds, you can easily deliver the latest version of your application into production with shorter build times, decreased resource and network usage, improved security, and a number of other advantages. OpenShift supports multiple build strategies and input sources.

For more information, see the Source-to-Image (S2I) Build chapter of the OpenShift Container Platform documentation.

You must provide three elements to the S2I process to assemble the final container image:

  • The application sources hosted in an online SCM repository, such as GitHub.

  • The S2I Builder image, which serves as the foundation for the assembled image and provides the ecosystem in which your application is running.

  • Optionally, you can also provide environment variables and parameters that are used by S2I scripts.

The process injects your application source and dependencies into the Builder image according to instructions specified in the S2I script, and generates a Docker-formatted container image that runs the assembled application. For more information, check the S2I build requirements, build options and how builds work sections of the OpenShift Container Platform documentation.

Appendix H: Proficiency levels

Each available mission teaches concepts that require certain minimum knowledge. This requirement varies by mission. The minimum requirements and concepts are organized in several levels of proficiency. In addition to the levels described here, you might need additional information specific to each mission.

Foundational

The missions rated at Foundational proficiency generally require no prior knowledge of the subject matter; they provide general awareness and demonstration of key elements, concepts, and terminology. There are no special requirements except those directly mentioned in the description of the mission.

Advanced

When using Advanced missions, the assumption is that you are familiar with the common concepts and terminology of the subject area of the mission in addition to Kubernetes and OpenShift. You must also be able to perform basic tasks on your own, for example configure services and applications, or administer networks. If a service is needed by the mission, but configuring it is not in the scope of the mission, the assumption is that you have the knowledge to to properly configure it, and only the resulting state of the service is described in the documentation.

Expert

Expert missions require the highest level of knowledge of the subject matter. You are expected to perform many tasks based on feature-based documentation and manuals, and the documentation is aimed at most complex scenarios.

Appendix I: Glossary

I.1. Product and project names

developers.redhat.com/launch

developers.redhat.com/launch is a standalone getting started experience offered by Red Hat for jumpstarting cloud-native application development on OpenShift. It provides a hassle-free way of creating functional example applications, called missions, as well as an easy way to build and deploy those missions to OpenShift.

Fabric8 Launcher

The Fabric8 Launcher is the upstream project on which developers.redhat.com/launch is based.

Single-node OpenShift Cluster

An OpenShift cluster running on your machine using Minishift.

I.2. Terms specific to Fabric8 Launcher

Booster

A language-specific implementation of a particular mission on a particular runtime. Boosters are listed in a booster catalog.

For example, a booster is a web service with a REST API implemented using the Thorntail runtime.

Booster Catalog

A Git repository that contains information about boosters.

Mission

An application specification, for example a web service with a REST API.

Missions generally do not specify which language or platform they should run on; the description only contains the intended functionality.

Runtime

A platform that executes boosters. For example, Thorntail or Eclipse Vert.x.