5.6. Java-based Operators
Java-based Operator SDK is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.
For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.
To demonstrate the basics of setting up and running a Java-based Operator using tools and libraries provided by the Operator SDK, Operator developers can build an example Java-based Operator for Memcached, a distributed key-value store, and deploy it to a cluster.
The Red Hat-supported version of the Operator SDK CLI tool, including the related scaffolding and testing tools for Operator projects, is deprecated and is planned to be removed in a future release of OpenShift Container Platform. Red Hat will provide bug fixes and support for this feature during the current release lifecycle, but this feature will no longer receive enhancements and will be removed from future OpenShift Container Platform releases.
The Red Hat-supported version of the Operator SDK is not recommended for creating new Operator projects. Operator authors with existing Operator projects can use the version of the Operator SDK CLI tool released with OpenShift Container Platform 4.16 to maintain their projects and create Operator releases targeting newer versions of OpenShift Container Platform.
The following related base images for Operator projects are not deprecated. The runtime functionality and configuration APIs for these base images are still supported for bug fixes and for addressing CVEs.
- The base image for Ansible-based Operator projects
- The base image for Helm-based Operator projects
For the most recent list of major functionality that has been deprecated or removed within OpenShift Container Platform, refer to the Deprecated and removed features section of the OpenShift Container Platform release notes.
For information about the unsupported, community-maintained, version of the Operator SDK, see Operator SDK (Operator Framework).
5.6.1.1. Prerequisites
- Operator SDK CLI installed
-
OpenShift CLI (
oc) 4.16+ installed - Java 11+
- Maven 3.6.3+
-
Logged into an OpenShift Container Platform 4.16 cluster with
ocwith an account that hascluster-adminpermissions - To allow the cluster to pull the image, the repository where you push your image must be set as public, or you must configure an image pull secret
5.6.1.2. Creating and deploying Java-based Operators
You can build and deploy a simple Java-based Operator for Memcached by using the Operator SDK.
Procedure
Create a project.
Create your project directory:
$ mkdir memcached-operatorChange into the project directory:
$ cd memcached-operatorRun the
operator-sdk initcommand with thequarkusplugin to initialize the project:$ operator-sdk init \ --plugins=quarkus \ --domain=example.com \ --project-name=memcached-operator
Create an API.
Create a simple Memcached API:
$ operator-sdk create api \ --plugins quarkus \ --group cache \ --version v1 \ --kind MemcachedBuild and push the Operator image.
Use the default
Makefiletargets to build and push your Operator. SetIMGwith a pull spec for your image that uses a registry you can push to:$ make docker-build docker-push IMG=<registry>/<user>/<image_name>:<tag>Run the Operator.
Install the CRD:
$ make installDeploy the project to the cluster. Set
IMGto the image that you pushed:$ make deploy IMG=<registry>/<user>/<image_name>:<tag>
Create a sample custom resource (CR).
Create a sample CR:
$ oc apply -f config/samples/cache_v1_memcached.yaml \ -n memcached-operator-systemWatch for the CR to reconcile the Operator:
$ oc logs deployment.apps/memcached-operator-controller-manager \ -c manager \ -n memcached-operator-system
Delete a CR.
Delete a CR by running the following command:
$ oc delete -f config/samples/cache_v1_memcached.yaml -n memcached-operator-systemClean up.
Run the following command to clean up the resources that have been created as part of this procedure:
$ make undeploy
5.6.1.3. Next steps
- See Operator SDK tutorial for Java-based Operators for a more in-depth walkthrough on building a Java-based Operator.
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