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Getting started with Operator SDK for Go-based Operators

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+ 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 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