simple-wordpress-operator

Simple Wordpress Operator

An example of simple Kubernetes operator.

This operator was created using Operator-SDK 1.14

Creating the Operator

Create directory of your project

$ mkdir simple-wordpress-operator
$ cd simple-wordpress-operator

Init the operator project

$ operator-sdk init --domain=simplewordpress.com --repo github.com/mgeri/simple-wordpress-operator

Create the CRDs and Controller for your operator

$ operator-sdk create api --group=simple-wordpress --version=v1alpha1 --kind=SimpleWordpress --resource=true --controller=true

The command creates the following files:

api/v1/simplewordpress_types.go
controllers/simplewordpress_controller.go

Change the api/v1/simplewordpress_types.goto include a new SqlRootPassword attribute in the WordpressSpec struct.

// SimpleWordpressSpec defines the desired state of SimpleWordpress
type SimpleWordpressSpec struct {
	// INSERT ADDITIONAL SPEC FIELDS - desired state of cluster
	// Important: Run "make" to regenerate code after modifying this file

	// MySql root password
	SqlRootPassword string `json:"sqlRootPassword"`
}

After you make the change in api/v1/simplewordpress_types.go, run the following commands to ensure that the changes are reflected in the. custom resource definitions (CRDs) in the config directory:

$ make generate
$ make manifests

Implement Controller

Change controllers\simplewordpress_controller.go.

The boiler-plate generated theSetupWithManager function creates watch for the primary resources:

For(&simplewordpressv1alpha1.SimpleWordpress{})

Watch also Deployment and Services as additional resources:

func (r *SimpleWordpressReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&simplewordpressv1alpha1.SimpleWordpress{}).
		Owns(&appsv1.Deployment{}).
		Owns(&corev1.Service{}).
		Complete(r)
}

Change the reconcile loop function to check and create MySQL and WordPress deployment and service.

Note: In this simple example we don't check or create any PV and PVC.

Run the Kubernetes Operator

You need a Kubernetes cluster like K3s, Kind, Minikube. Set it as your current kube context.

Enter the following command to build and run operator:

$ make install run

Your config/samples/simple-wordpress_v1alpha1_simplewordpress.yaml should look something like:

apiVersion: simple-wordpress.simplewordpress.com/v1alpha1
kind: SimpleWordpress
metadata:
  name: simplewordpress-sample
spec:
  sqlRootPassword: "mypassword"

Create the SimpleWorkdpress deployment sample using Kustomize

$ kubectl create -k config/samples/

After few seconds the MySql and WordPress deployments and services are created. If you try to delete a deployment it will be recreated by operator.