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+ installed

  • Logged into an OKD 4 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:

      $ mkdir nginx-operator
    2. Change into the project directory:

      $ cd nginx-operator
    3. Run the operator-sdk init command with the helm plug-in 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. 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
  6. Clean up.

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

    $ make undeploy

Next steps