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

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:

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

      1. $ cd nginx-operator
    3. Run the operator-sdk init command with the helm plug-in to initialize the project:

      1. $ operator-sdk init \
      2. --plugins=helm
  2. Create an API.

    Create a simple Nginx API:

    1. $ operator-sdk create api \
    2. --group demo \
    3. --version v1 \
    4. --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:

    1. $ make docker-build docker-push IMG=<registry>/<user>/<image_name>:<tag>
  4. Run the Operator.

    1. Install the CRD:

      1. $ make install
    2. Deploy the project to the cluster. Set IMG to the image that you pushed:

      1. $ 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 OKD. Add the following SCC to the service account for the nginx-sample pod:

    1. $ oc adm policy add-scc-to-user \
    2. anyuid system:serviceaccount:nginx-operator-system:nginx-sample
  6. Create a sample custom resource (CR).

    1. Create a sample CR:

      1. $ oc apply -f config/samples/demo_v1_nginx.yaml \
      2. -n nginx-operator-system
    2. Watch for the CR to reconcile the Operator:

      1. $ oc logs deployment.apps/nginx-operator-controller-manager \
      2. -c manager \
      3. -n nginx-operator-system
  7. Clean up.

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

    1. $ make undeploy

Next steps