Getting started with Operator SDK for Helm-based Operators

• Prerequisites
• Creating and deploying Helm-based Operators
• Next steps

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 OKD 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 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. 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:

   $ 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. Clean up.

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

   $ make undeploy

Next steps

• See Operator SDK tutorial for Helm-based Operators for a more in-depth walkthrough on building a Helm-based Operator.