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Connecting an application to a <strong>service</strong> using the Developer perspective - Connecting applications to <strong>service</strong>s | Building applications | OpenShift Container Platform 4.11
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Connecting an application to a service using the Developer perspective

In addition to grouping multiple components within an application, you can also use the Topology view to connect components with each other. You can either use a binding connector or a visual one to connect components.

A binding connection between the components can be established only if the target node is an Operator-backed service. This is indicated by the Create a binding connector tool-tip which appears when you drag an arrow to such a target node. When an application is connected to a service by using a binding connector a serviceBinding resource is created. Then, the service Binding Operator controller projects the necessary binding data into the application deployment. After the request is successful, the application is redeployed establishing an interaction between the connected components.

A visual connector establishes only a visual connection between the components, depicting an intent to connect. No interaction between the components is established. If the target node is not an Operator-backed service the Create a visual connector tool-tip is displayed when you drag an arrow to a target node.

Discovering and identifying Operator-backed bindable services

As a user, if you want to create a bindable service, you must know which services are bindable. Bindable services are services that the applications can consume easily because they expose their binding data such as credentials, connection details, volume mounts, secrets, and other binding data in a standard way. The Developer perspective helps you discover and identify such bindable services.

Procedure

  • To discover and identify Operator-backed bindable services, consider the following alternative approaches:

    • Click +Add → Developer Catalog → Operator Backed to see the Operator-backed tiles. Operator-backed services that support service binding features have a Bindable badge on the tiles.

    • On the left pane of the Operator Backed page, select the Bindable checkbox.

      Click the help icon next to service binding to see more information about bindable services.

    • Click +Add → Add and search for Operator-backed services. When you click the bindable service, you can view the Bindable badge in the side panel to the right.

Creating a visual connection between components

You can depict an intent to connect application components by using the visual connector.

This procedure walks you through an example of creating a visual connection between a PostgreSQL Database service and a Spring PetClinic sample application.

Prerequisites

  • You have created and deployed a Spring PetClinic sample application by using the Developer perspective.

  • You have created and deployed a Crunchy PostgreSQL database instance by using the Developer perspective. This instance has the following components: hippo-backup, hippo-instance, hippo-repo-host, and hippo-pgbouncer.

Procedure

  1. Hover over the Spring PetClinic sample application to see a dangling arrow on the node.

    odc connector
    Figure 1. Visual connector

  2. Click and drag the arrow towards the hippo-pgbouncer deployment to connect the Spring PetClinic sample application with it.

  3. Click the spring-petclinic deployment to see the Overview panel. Under the Details tab, click the edit icon in the Annotations section to see the Key = app.openshift.io/connects-to and Value = [{"apiVersion":"apps/v1","kind":"Deployment","name":"hippo-pgbouncer"}] annotation added to the deployment.

  4. Optional: You can repeat these steps to establish visual connections between other applications and components you create.

    odc connecting multiple applications
    Figure 2. Connecting multiple applications

Creating a binding connection between components

You can establish a binding connection with Operator-backed components.

This procedure walks through an example of creating a binding connection between a PostgreSQL Database service and a Spring PetClinic sample application. To create a binding connection with a service that is backed by the PostgreSQL Database Operator, you must first add the Red Hat-provided PostgreSQL Database Operator to the OperatorHub, and then install the Operator. The PostreSQL Database Operator then creates and manages the Database resource, which exposes the binding information in secrets, config maps, status, and spec attributes.

Prerequisites

  • You have created and deployed a Spring PetClinic sample application by using the Developer perspective.

  • You have installed service Binding Operator from the OperatorHub.

  • You have installed the Crunchy Postgres for Kubernetes Operator from the OperatorHub by using the v5 Update channel.

  • You have created and deployed a Crunchy PostgreSQL database instance by using the Developer perspective. This instance has the following components: hippo-backup, hippo-instance, hippo-repo-host, and hippo-pgbouncer.

Procedure

  1. Switch to the Developer perspective and ensure that you are in the appropriate project, for example, my-petclinic.

  2. In the Topology view, hover over the Spring PetClinic sample application to see a dangling arrow on the node.

  3. Click and drag the arrow towards the hippo database in the Postgres Cluster to make a binding connection with the Spring PetClinic sample application.

    1. Enter the name and click Create.

      odc sbc modal
      Figure 3. service Binding dialog

Alternatively, in the +Add view, click the YAML option to see the Import YAML screen. Use the YAML editor and add the serviceBinding resource:

apiVersion: binding.operators.coreos.com/v1alpha1
kind: serviceBinding
metadata:
    name: spring-petclinic-pgcluster
    namespace: my-petclinic
spec:
    services:
    - group: postgres-operator.crunchydata.com
      version: v1beta1
      kind: PostgresCluster
      name: hippo
    application:
      name: spring-petclinic
      group: apps
      version: v1
      resource: deployments

A service binding request is created and the service Binding Operator controller projects the database service connection information into the application deployment as files by using a volume mount. After the request is successful, the application is redeployed and the connection is established.

odc binding connector
Figure 4. Binding connector

You can also use the context menu by dragging the dangling arrow to add and create a binding connection to an operator-backed service.

odc context operator
Figure 5. Context menu to create binding connection

Verifying the status of your service binding from the Topology view

The Developer perspective helps you verify the status of your service binding through the Topology view.

Procedure

  1. If a service binding was successful, click the binding connector. A side panel appears displaying the Connected status under the Details tab.

    Optionally, you can view the Connected status on the following pages from the Developer perspective:

    • The serviceBindings page.

    • The serviceBinding details page. In addition, the page title displays a Connected badge.

  2. If a service binding was unsuccessful, the binding connector shows a red arrowhead and a red cross in the middle of the connection. Click this connector to view the Error status in the side panel under the Details tab. Optionally, click the Error status to view specific information about the underlying problem.

    You can also view the Error status and a tooltip on the following pages from the Developer perspective:

    • The serviceBindings page.

    • The serviceBinding details page. In addition, the page title displays an Error badge.

In the serviceBindings page, use the Filter dropdown to list the service bindings based on their status.

Additional resources