Chapter 3. Creating applications

Procedure

1. Select Developer from the context selector at the top of the web console navigation menu.
2. While in the desired project, click +Add
3. Click All services in the Developer Catalog tile.

4. Click Builder Images under Type to see the available builder images.

   Note

   Only image stream tags that have the

   builder

   tag listed in their annotations appear in this list, as demonstrated here:

   kind: "ImageStream"
   apiVersion: "v1"
   metadata:
     name: "ruby"
     creationTimestamp: null
   spec:
   # ...
     tags:
       - name: "2.6"
         annotations:
           description: "Build and run Ruby 2.6 applications"
           iconClass: "icon-ruby"
           tags: "builder,ruby" 

   1

   
           supports: "ruby:2.6,ruby"
           version: "2.6"
   # ...

   1

   Including builder here ensures this image stream tag appears in the web console as a builder.

5. Modify the settings in the new application screen to configure the objects to support your application.

Procedure

1. You can list the available default instant app and quick start templates with:

   $ oc get templates -n openshift

2. To modify the source and build your own version of the application:

   1. Fork the repository referenced by the template’s default

      SOURCE_REPOSITORY_URL

      parameter.

   2. Override the value of the

      SOURCE_REPOSITORY_URL

      parameter when creating from the template, specifying your fork instead of the default value.

      By doing this, the build configuration created by the template now points to your fork of the application code, and you can modify the code and rebuild the application at will.

Procedure

1. In the +Add view, click the Samples tile to see the Samples page.
2. On the Samples page, select one of the available sample applications to see the Create Sample Application form.

3. In the Create Sample Application Form:

   • In the Name field, the deployment name is displayed by default. You can modify this name as required.
   • In the Builder Image Version, a builder image is selected by default. You can modify this image version by using the Builder Image Version drop-down list.
   • A sample Git repository URL is added by default.
4. Click Create to create the sample application. The build status of the sample application is displayed on the Topology view. After the sample application is created, you can see the deployment added to the application.

Procedure

1. In the +Add view, click the Getting Started resources Build with guided documentation View all quick starts link to view the Quick Starts page.
2. In the Quick Starts page, click the tile for the quick start that you want to use.
3. Click Start to begin the quick start.
4. Perform the steps that are displayed.

Procedure

1. In the +Add view, click From Git in the Git Repository tile to see the Import from git form.
2. In the Git section, enter the Git repository URL for the codebase you want to use to create an application. For example, enter the URL of this sample Node.js application

   https://github.com/sclorg/nodejs-ex

   . The URL is then validated.

3. Optional: You can click Show Advanced Git Options to add details such as:

   • Git Reference to point to code in a specific branch, tag, or commit to be used to build the application.
   • Context Dir to specify the subdirectory for the application source code you want to use to build the application.
   • Source Secret to create a Secret Name with credentials for pulling your source code from a private repository.

4. Optional: You can import a

   Devfile

   , a

   Dockerfile

   ,

   Builder Image

   , or a

   Serverless Function

   through your Git repository to further customize your deployment.
   • If your Git repository contains a

     Devfile

     , a

     Dockerfile

     , a

     Builder Image

     , or a

     func.yaml

     , it is automatically detected and populated on the respective path fields.
   • If a

     Devfile

     , a

     Dockerfile

     , or a

     Builder Image

     are detected in the same repository, the

     Devfile

     is selected by default.
   • If

     func.yaml

     is detected in the Git repository, the Import Strategy changes to

     Serverless Function

     .
   • Alternatively, you can create a serverless function by clicking Create Serverless function in the +Add view using the Git repository URL.
   • To edit the file import type and select a different strategy, click Edit import strategy option.
   • If multiple

     Devfiles

     , a

     Dockerfiles

     , or a

     Builder Images

     are detected, to import a specific instance, specify the respective paths relative to the context directory.

5. After the Git URL is validated, the recommended builder image is selected and marked with a star. If the builder image is not auto-detected, select a builder image. For the

   https://github.com/sclorg/nodejs-ex

   Git URL, by default the Node.js builder image is selected.
   1. Optional: Use the Builder Image Version drop-down to specify a version.
   2. Optional: Use the Edit import strategy to select a different strategy.
   3. Optional: For the Node.js builder image, use the Run command field to override the command to run the application.

6. In the General section:

   1. In the Application field, enter a unique name for the application grouping, for example,

      myapp

      . Ensure that the application name is unique in a namespace.

   2. The Name field to identify the resources created for this application is automatically populated based on the Git repository URL if there are no existing applications. If there are existing applications, you can choose to deploy the component within an existing application, create a new application, or keep the component unassigned.

      Note

      The resource name must be unique in a namespace. Modify the resource name if you get an error.

7. In the Resources section, select:

   • Deployment, to create an application in plain Kubernetes style.
   • Deployment Config, to create an OpenShift Container Platform style application.

   • Serverless Deployment, to create a Knative service.

     Note

     To set the default resource preference for importing an application, go to User Preferences Applications Resource type field. The Serverless Deployment option is displayed in the Import from Git form only if the OpenShift Serverless Operator is installed in your cluster. The Resources section is not available while creating a serverless function. For further details, refer to the OpenShift Serverless documentation.

8. In the Pipelines section, select Add Pipeline, and then click Show Pipeline Visualization to see the pipeline for the application. A default pipeline is selected, but you can choose the pipeline you want from the list of available pipelines for the application.

   Note

   The Add pipeline checkbox is checked and Configure PAC is selected by default if the following criterias are fulfilled:

   • Pipeline operator is installed

   • pipelines-as-code

     is enabled

   • .tekton

     directory is detected in the Git repository

9. Add a webhook to your repository. If Configure PAC is checked and the GitHub App is set up, you can see the Use GitHub App and Setup a webhook options. If GitHub App is not set up, you can only see the Setup a webhook option:

   1. Go to Settings Webhooks and click Add webhook.
   2. Set the Payload URL to the Pipelines as Code controller public URL.
   3. Select the content type as application/json.
   4. Add a webhook secret and note it in an alternate location. With

      openssl

      installed on your local machine, generate a random secret.
   5. Click Let me select individual events and select these events: Commit comments, Issue comments, Pull request, and Pushes.
   6. Click Add webhook.

10. Optional: In the Advanced Options section, the Target port and the Create a route to the application is selected by default so that you can access your application using a publicly available URL.

    If your application does not expose its data on the default public port, 80, clear the check box, and set the target port number you want to expose.

11. Optional: You can use the following advanced options to further customize your application:

    Routing

    By clicking the Routing link, you can perform the following actions:

    • Customize the hostname for the route.
    • Specify the path the router watches.
    • Select the target port for the traffic from the drop-down list.

    • Secure your route by selecting the Secure Route check box. Select the required TLS termination type and set a policy for insecure traffic from the respective drop-down lists.

      Note

      For serverless applications, the Knative service manages all the routing options above. However, you can customize the target port for traffic, if required. If the target port is not specified, the default port of

      8080

      is used.

    Domain mapping

    If you are creating a Serverless Deployment, you can add a custom domain mapping to the Knative service during creation.

    • In the Advanced options section, click Show advanced Routing options.

      • If the domain mapping CR that you want to map to the service already exists, you can select it from the Domain mapping drop-down menu.
      • If you want to create a new domain mapping CR, type the domain name into the box, and select the Create option. For example, if you type in

        example.com

        , the Create option is Create "example.com".

    Health Checks

    Click the Health Checks link to add Readiness, Liveness, and Startup probes to your application. All the probes have prepopulated default data; you can add the probes with the default data or customize it as required.

    To customize the health probes:

    • Click Add Readiness Probe, if required, modify the parameters to check if the container is ready to handle requests, and select the check mark to add the probe.
    • Click Add Liveness Probe, if required, modify the parameters to check if a container is still running, and select the check mark to add the probe.

    • Click Add Startup Probe, if required, modify the parameters to check if the application within the container has started, and select the check mark to add the probe.

      For each of the probes, you can specify the request type - HTTP GET, Container Command, or TCP Socket, from the drop-down list. The form changes as per the selected request type. You can then modify the default values for the other parameters, such as the success and failure thresholds for the probe, number of seconds before performing the first probe after the container starts, frequency of the probe, and the timeout value.

    Build Configuration and Deployment

    Click the Build Configuration and Deployment links to see the respective configuration options. Some options are selected by default; you can customize them further by adding the necessary triggers and environment variables.

    For serverless applications, the Deployment option is not displayed as the Knative configuration resource maintains the desired state for your deployment instead of a

    DeploymentConfig

    resource.

    Scaling

    Click the Scaling link to define the number of pods or instances of the application you want to deploy initially.

    If you are creating a serverless deployment, you can also configure the following settings:

    • Min Pods determines the lower limit for the number of pods that must be running at any given time for a Knative service. This is also known as the

      minScale

      setting.
    • Max Pods determines the upper limit for the number of pods that can be running at any given time for a Knative service. This is also known as the

      maxScale

      setting.
    • Concurrency target determines the number of concurrent requests desired for each instance of the application at a given time.
    • Concurrency limit determines the limit for the number of concurrent requests allowed for each instance of the application at a given time.
    • Concurrency utilization determines the percentage of the concurrent requests limit that must be met before Knative scales up additional pods to handle additional traffic.
    • Autoscale window defines the time window over which metrics are averaged to provide input for scaling decisions when the autoscaler is not in panic mode. A service is scaled-to-zero if no requests are received during this window. The default duration for the autoscale window is

      60s

      . This is also known as the stable window.

    Resource Limit

    Click the Resource Limit link to set the amount of CPU and Memory resources a container is guaranteed or allowed to use when running.

    Labels

    Click the Labels link to add custom labels to your application.

12. Click Create to create the application and a success notification is displayed. You can see the build status of the application in the Topology view.

Procedure

1. In the +Add view, click Container images to view the Deploy Images page.

2. In the Image section:

   1. Select Image name from external registry to deploy an image from a public or a private registry, or select Image stream tag from internal registry to deploy an image from an internal registry.
   2. Select an icon for your image in the Runtime icon tab.

3. In the General section:

   1. In the Application name field, enter a unique name for the application grouping.
   2. In the Name field, enter a unique name to identify the resources created for this component.

4. In the Resource type section, select the resource type to generate:

   1. Select Deployment to enable declarative updates for

      Pod

      and

      ReplicaSet

      objects.
   2. Select DeploymentConfig to define the template for a

      Pod

      object, and manage deploying new images and configuration sources.
   3. Select Serverless Deployment to enable scaling to zero when idle.
5. Click Create. You can view the build status of the application in the Topology view.

Procedure

1. In the Topology view, right-click anywhere to view the Add to Project menu.
2. Hover over the Add to Project menu to see the menu options, and then select the Upload JAR file option to see the Upload JAR file form. Alternatively, you can drag the JAR file into the Topology view.
3. In the JAR file field, browse for the required JAR file on your local machine and upload it. Alternatively, you can drag the JAR file on to the field. A toast alert is displayed at the top right if an incompatible file type is dragged into the Topology view. A field error is displayed if an incompatible file type is dropped on the field in the upload form.
4. The runtime icon and builder image are selected by default. If a builder image is not auto-detected, select a builder image. If required, you can change the version using the Builder Image Version drop-down list.
5. Optional: In the Application Name field, enter a unique name for your application to use for resource labelling.
6. In the Name field, enter a unique component name for the associated resources.
7. Optional: Use the Resource type drop-down list to change the resource type.
8. In the Advanced options menu, click Create a Route to the Application to configure a public URL for your deployed application.
9. Click Create to deploy the application. A toast notification is shown to notify you that the JAR file is being uploaded. The toast notification also includes a link to view the build logs.

Procedure

1. Navigate to Developer Perspective +Add Developer Catalog All Services. A list of all the available services in the Developer Catalog is displayed.
2. Under Type, click Devfiles to browse for devfiles that support a particular language or framework. Alternatively, you can use the keyword filter to search for a particular devfile using their name, tag, or description.
3. Click the devfile you want to use to create an application. The devfile tile displays the details of the devfile, including the name, description, provider, and the documentation of the devfile.
4. Click Create to create an application and view the application in the Topology view.

Procedure

1. In the Developer perspective, navigate to the +Add view and from the Developer Catalog tile, click All Services to view all the available services in the Developer Catalog.
2. Under All Services, select the kind of service or the component you need to add to your project. For this example, select Databases to list all the database services and then click MariaDB to see the details for the service.

3. Click Instantiate Template to see an automatically populated template with details for the MariaDB service, and then click Create to create and view the MariaDB service in the Topology view.

   Figure 3.1. MariaDB in Topology

   

Procedure

1. Create a new project in the OpenShift Container Platform web console for this procedure. This example uses a project called

   my-etcd

   .

2. Navigate to the Operators Installed Operators page. The Operators that have been installed to the cluster by the cluster administrator and are available for use are shown here as a list of cluster service versions (CSVs). CSVs are used to launch and manage the software provided by the Operator.

   Tip

   You can get this list from the CLI using:

   $ oc get csv

3. On the Installed Operators page, click the etcd Operator to view more details and available actions.

   As shown under Provided APIs, this Operator makes available three new resource types, including one for an etcd Cluster (the

   EtcdCluster

   resource). These objects work similar to the built-in native Kubernetes ones, such as

   Deployment

   or

   ReplicaSet

   , but contain logic specific to managing etcd.

4. Create a new etcd cluster:

   1. In the etcd Cluster API box, click Create instance.
   2. The next page allows you to make any modifications to the minimal starting template of an

      EtcdCluster

      object, such as the size of the cluster. For now, click Create to finalize. This triggers the Operator to start up the pods, services, and other components of the new etcd cluster.

5. Click the example etcd cluster, then click the Resources tab to see that your project now contains a number of resources created and configured automatically by the Operator.

   Verify that a Kubernetes service has been created that allows you to access the database from other pods in your project.

6. All users with the

   edit

   role in a given project can create, manage, and delete application instances (an etcd cluster, in this example) managed by Operators that have already been created in the project, in a self-service manner, just like a cloud service. If you want to enable additional users with this ability, project administrators can add the role using the following command:

   $ oc policy add-role-to-user edit <user> -n <target_project>

Procedure

1. Install the database:

   $ sudo yum install -y postgresql postgresql-server postgresql-devel

2. Initialize the database:

   $ sudo postgresql-setup initdb

   This command creates the

   /var/lib/pgsql/data

   directory, in which the data is stored.

3. Start the database:

   $ sudo systemctl start postgresql.service

4. When the database is running, create your

   rails

   user:

   $ sudo -u postgres createuser -s rails

   Note that the user created has no password.

Procedure

1. Install the Rails gem:

   $ gem install rails

   Example output

   Successfully installed rails-4.3.0
   1 gem installed

2. After you install the Rails gem, create a new application with PostgreSQL as your database:

   $ rails new rails-app --database=postgresql

3. Change into your new application directory:

   $ cd rails-app

4. If you already have an application, make sure the

   pg

   (postgresql) gem is present in your

   Gemfile

   . If not, edit your

   Gemfile

   by adding the gem:

   gem 'pg'

5. Generate a new

   Gemfile.lock

   with all your dependencies:

   $ bundle install

6. In addition to using the

   postgresql

   database with the

   pg

   gem, you also must ensure that the

   config/database.yml

   is using the

   postgresql

   adapter.

   Make sure you updated

   default

   section in the

   config/database.yml

   file, so it looks like this:

   default: &default
     adapter: postgresql
     encoding: unicode
     pool: 5
     host: localhost
     username: rails
     password: <password>

7. Create your application’s development and test databases:

   $ rake db:create

   This creates

   development

   and

   test

   database in your PostgreSQL server.