Getting started with Operator SDK for Go-based Operators

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

To demonstrate the basics of setting up and running a Go-based Operator using tools and libraries provided by the Operator SDK, Operator developers can build an example Go-based Operator for Memcached, a distributed key-value store, 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 Go-based Operators

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

Procedure

1. Create a project.

   1. Create your project directory:

      $ mkdir memcached-operator

   2. Change into the project directory:

      $ cd memcached-operator

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

      $ operator-sdk init \
          --domain=example.com \
          --repo=github.com/example-inc/memcached-operator

      The command uses the Go plug-in by default.

2. Create an API.

   Create a simple Memcached API:

   $ operator-sdk create api \
       --resource=true \
       --controller=true \
       --group cache \
       --version v1 \
       --kind Memcached

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/cache_v1_memcached.yaml \
          -n memcached-operator-system

   2. Watch for the CR to reconcile the Operator:

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

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