Operator pattern overview in Kubernetes - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a basic Custom Resource Definition (CRD) in Kubernetes.

Kubernetes

apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: myresources.example.com
spec:
  group: example.com
  versions:
  - name: v1
    served: true
    storage: true
  scope: [1]
  names:
    plural: myresources
    singular: myresource
    kind: MyResource
    shortNames:
    - mr

Drag options to blanks, or click blank then click option'

AGlobal

BNamespaced

CCluster

DUniversal

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Cluster' when the resource should be namespaced.

Confusing 'Global' or 'Universal' which are not valid scope values.

The scope field defines if the CRD is namespaced or cluster-wide. Namespaced means the resource exists within a namespace.

2fill in blank

medium

Complete the command to create an Operator using the Operator SDK CLI.

Kubernetes

operator-sdk init --domain example.com --repo github.com/example/[1]

Drag options to blanks, or click blank then click option'

Ak8s-operator

Boperator-sdk

Cmy-operator

Dexample-operator

Attempts:

3 left

💡 Hint

Common Mistakes

Using generic names like 'operator-sdk' which is the tool name, not the repo.

Using names with spaces or invalid characters.

The --repo flag specifies the Go module path for the operator project. It is common to name it after your operator, like my-operator.

3fill in blank

hard

Fix the error in the reconciliation function signature in a Go Operator controller.

Kubernetes

func (r *MyResourceReconciler) Reconcile(ctx context.Context, req [1]) (ctrl.Result, error) {

Drag options to blanks, or click blank then click option'

Actrl.Request

Bclient.Request

Creconcile.Request

DRequest

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect package prefixes like client.Request or reconcile.Request.

Omitting the package prefix causing undefined type errors.

The Reconcile method receives a ctrl.Request parameter which contains information about the object to reconcile.

4fill in blank

hard

Fill both blanks to create a watch on a Kubernetes resource in the Operator controller setup.

Kubernetes

func (r *MyResourceReconciler) SetupWithManager(mgr ctrl.Manager) error {
  return ctrl.NewControllerManagedBy(mgr).
    For(&[1]{}).
    Owns(&[2]{}).
    Complete(r)
}

Drag options to blanks, or click blank then click option'

Aexamplev1.MyResource

Bcorev1.Pod

Cappsv1.Deployment

Dbatchv1.Job

Attempts:

3 left

💡 Hint

Common Mistakes

Using corev1.Pod as the primary resource instead of the custom resource.

Mixing up the order of For and Owns.

The For method watches the primary resource type, here MyResource. The Owns method watches related resources like Deployment owned by the operator.

5fill in blank

hard

Fill all three blanks to define a simple reconciliation loop that fetches a resource, checks if it exists, and returns without error if not found.

Kubernetes

func (r *MyResourceReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
  var resource [1]
  err := r.Client.Get(ctx, req.NamespacedName, &[3])
  if [2] {
    if errors.IsNotFound(err) {
      return ctrl.Result{}, nil
    }
    return ctrl.Result{}, err
  }
  // Continue reconciliation logic here
  return ctrl.Result{}, nil
}

Drag options to blanks, or click blank then click option'

Aexamplev1.MyResource

Berr == nil

Cerr != nil

Dresource

Attempts:

3 left

💡 Hint

Common Mistakes

Checking if err == nil instead of err != nil.

Using wrong variable types for the resource.

Not passing the address of the resource variable to Get.

The variable resource is of the custom resource type. The code checks if err != nil to handle errors. The variable resource is passed to Get to fetch the object.