Getting started with Operator SDK for Ansible-based Operators

Getting started with Operator SDK for Ansible-based Operators

The Operator SDK includes options for generating an Operator project that leverages existing Ansible playbooks and modules 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 Ansible-based Operator using tools and libraries provided by the Operator SDK, Operator developers can build an example Ansible-based Operator for Memcached, a distributed key-value store, and deploy it to a cluster.

Prerequisites

Operator SDK CLI installed
OpenShift CLI (oc) v4.11+ installed
Ansible v2.9.0
Ansible Runner v2.0.2+
Ansible Runner HTTP Event Emitter plug-in v1.0.0+
Python 3.8.6+
OpenShift Python client v0.12.0+
Logged into an OKD 4.11 cluster with oc with an account that has cluster-admin permissions
To allow the cluster to 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 Ansible-based Operators

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

Procedure

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 with the ansible plug-in to initialize the project:
```
$ operator-sdk init \
    --plugins=ansible \
    --domain=example.com
```

Create an API.

Create a simple Memcached API:

$ operator-sdk create api \
    --group cache \
    --version v1 \
    --kind Memcached \
    --generate-role (1)

1	Generates an Ansible role for the API.

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>
```
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>
```

Create a sample custom resource (CR).

Create a sample CR:

$ oc apply -f config/samples/cache_v1_memcached.yaml \
    -n memcached-operator-system

Watch for the CR to reconcile the Operator:

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

Example output

...
I0205 17:48:45.881666       7 leaderelection.go:253] successfully acquired lease memcached-operator-system/memcached-operator
{"level":"info","ts":1612547325.8819902,"logger":"controller-runtime.manager.controller.memcached-controller","msg":"Starting EventSource","source":"kind source: cache.example.com/v1, Kind=Memcached"}
{"level":"info","ts":1612547325.98242,"logger":"controller-runtime.manager.controller.memcached-controller","msg":"Starting Controller"}
{"level":"info","ts":1612547325.9824686,"logger":"controller-runtime.manager.controller.memcached-controller","msg":"Starting workers","worker count":4}
{"level":"info","ts":1612547348.8311093,"logger":"runner","msg":"Ansible-runner exited successfully","job":"4037200794235010051","name":"memcached-sample","namespace":"memcached-operator-system"}

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 Ansible-based Operators for a more in-depth walkthrough on building an Ansible-based Operator.