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Getting started with Operator SDK for Helm-based Operators

The Operator SDK includes options for generating an Operator project that leverages existing Helm charts to deploy Kubernetes resources as a unified application, without having to write any Go code.

To demonstrate the basics of setting up and running an Helm-based Operator using tools and libraries provided by the Operator SDK, Operator developers can build an example Helm-based Operator for Nginx and deploy it to a cluster.

Prerequisites

  • Operator SDK CLI installed

  • OpenShift CLI (oc) v4.9+ installed

  • Logged into an OpenShift Container Platform 4.9 cluster with oc with an account that has cluster-admin permissions

  • To allow the cluster pull the image, the repository where you push your image must be set as public, or you must configure an image pull secret

Creating and deploying Helm-based Operators

You can build and deploy a simple Helm-based Operator for Nginx by using the Operator SDK.

Procedure

  1. Create a project.

    1. Create your project directory:

      $ mkdir nginx-operator

    2. Change into the project directory:

      $ cd nginx-operator

    3. Run the operator-sdk init command with the helm plugin to initialize the project:

      $ operator-sdk init \
    --plugins=helm

  2. Create an API.

    Create a simple Nginx API:

    $ operator-sdk create api \
    --group demo \
    --version v1 \
    --kind Nginx

    This API uses the built-in Helm chart boilerplate from the helm create command.

  3. Build and push the Operator image.

    Use the default Makefile targets to build and push your Operator. Set IMG with 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>

  4. Run the Operator.

    1. Install the CRD:

      $ make install

    2. Deploy the project to the cluster. Set IMG to the image that you pushed:

      $ make deploy IMG=<registry>/<user>/<image_name>:<tag>

  5. Add a security context constraint (SCC).

    The Nginx service account requires privileged access to run in OpenShift Container Platform. Add the following SCC to the service account for the nginx-sample pod:

    $ oc adm policy add-scc-to-user \
    anyuid system:serviceaccount:nginx-operator-system:nginx-sample

  6. Create a sample custom resource (CR).

    1. Create a sample CR:

      $ oc apply -f config/samples/demo_v1_nginx.yaml \
    -n nginx-operator-system

    2. Watch for the CR to reconcile the Operator:

      $ oc logs deployment.apps/nginx-operator-controller-manager \
    -c manager \
    -n nginx-operator-system

  7. Delete a CR

    Delete a CR by running the following command:

    $ oc delete -f config/samples/cache_v1_memcached.yaml -n memcached-operator-system

  8. Clean up.

    Run the following command to clean up the resources that have been created as part of this procedure:

    $ make undeploy

Next steps