Chapter 2. Application life cycle management

Procedure

1. In the Add view, click From Git 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 nodejs application https://github.com/sclorg/nodejs-ex.

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. In the Builder section, select the required builder image to see the details of the builder image. If required, you can change the version using the Builder Image Version drop-down list. For example, select the Node.js builder image.

5. In the General section:

   1. In the Application Name 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.

      Note

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

6. In the Serverless section, select Enable scaling to zero when idle to create a serverless application that automatically scales your Pods to zero to prevent consumption of resources when idle.

   Note

   The Serverless section is displayed in the Import from git form only if the Serverless Operator is installed in your cluster. For further details refer to documentation on installing OpenShift Serverless.

7. In the Advanced Options section, the Create a route to the application is selected by default so that you can access your application using a publicly available URL. You can clear the check box if you do not want to expose your application on a public route.

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

   Routing

   Click the Routing link to:

   • 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.

     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.

   Build and Deployment Configuration

   Click the Build Configuration and Deployment Configuration links to see the respective configuration options. Some of the options are selected by default; you can customize them further by adding the necessary triggers and environment variables. For serverless applications, the Deployment Configuration option is not displayed as the Knative configuration resource maintains the desired state for your deployment instead of a DeploymentConfig.

   Scaling

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

   For serverless applications, you can:

   • Set the upper and lower limit for the number of pods that can be set by the autoscaler. If the lower limit is not specified, it defaults to zero.
   • Define the soft limit for the required number of concurrent requests per instance of the application at a given time. It is the recommended configuration for autoscaling. If not specified, it takes the value specified in the cluster configuration.
   • Define the hard limit for the number of concurrent requests allowed per instance of the application at a given time. This is configured in the revision template. If not specified, it defaults to the value specified in the cluster configuration.

   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.

9. Click Create to create the application and see its build status in the Topology view.

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 ClusterServiceVersions (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 Copied, and then click the etcd Operator to view more details and available actions:

   Figure 2.1. etcd Operator overview

   

   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 Deployments or ReplicaSets, but contain logic specific to managing etcd.

4. Create a new etcd cluster:

   1. In the etcd Cluster API box, click Create New.
   2. The next screen 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 Resources tab to see that your project now contains a number of resources created and configured automatically by the Operator.

   Figure 2.2. etcd Operator resources

   

   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. Create and deploy the MongoDB service to your project as follows:

   1. In the Developer perspective, navigate to the Add view and select the Database option to see the Developer Catalog, which has multiple options that you can add as components or services to your application.
   2. Click on the MongoDB option to see the details for the service.
   3. Click Instantiate Template to see an automatically populated template with details for the MongoDB service, and click Create to create the service.
2. On the left navigation panel, click Topology to see the MongoDB service deployed in your project.
3. To add the MongoDB service to the existing application group, select the mongodb Pod and drag it to the application; the MongoDB service is added to the existing application group.

4. Dragging a component and adding it to an application group automatically adds the required labels to the component. Click on the MongoDB service node to see the label app.kubernetes.io/part-of=myapp added to the Labels section in the Overview Panel.

   

1. To add the MongoDB service to your application, click on the mongodb Pod to see the Overview panel to the right.
2. Click the Actions drop-down menu on the upper right of the panel and select Edit Application Grouping.
3. In the Edit Application Grouping dialog box, click the Select an Application drop-down list, and select the appropriate application group.
4. Click Save to see the MongoDB service added to the application group.

Procedure

1. Hover over the MongoDB service to see a dangling arrow on the node.

   
2. Click and drag the arrow towards the Node.js component to connect the MongoDB service with it.

3. Click on the MongoDB service to see the Overview Panel. In the Annotations section, click the edit icon to see the Key = app.openshift.io/connects-to and Value = nodejs-ex annotation added to the service.

   

   Similarly you can create other applications and components and establish connections between them.