custom-kubernetes-operator

Prerequisite

• Docker
• Kubernetes
• Go 1.19+ (support go module)

Checkout

First, clone the application to any directory as long as not in GOPATH (since this project use Go Module, so clonning in GOPATH is not recommended)

$ git clone git@github.com:ligert/custom-kubernetes-operator.git 

$ cd custom-kubernetes-operator

Unit Tests

To run unit tests, run this command

$ make test

Deployment

To run the deployment, run this command

$ make deploy

The output should be something similar to this

test -s /home/custom-kubernetes-operator/bin/controller-gen || GOBIN=/home/custom-kubernetes-operator/bin go install sigs.k8s.io/controller-tools/cmd/controller-gen@v0.10.0
/home/custom-kubernetes-operator/bin/controller-gen rbac:roleName=manager-role crd webhook paths="./..." output:crd:artifacts:config=config/crd/bases
test -s /home/custom-kubernetes-operator/bin/kustomize || { curl -Ss "https://raw.githubusercontent.com/kubernetes-sigs/kustomize/master/hack/install_kustomize.sh" | bash -s -- 3.8.7 /home/custom-kubernetes-operator/bin; }
cd config/manager && /home/custom-kubernetes-operator/bin/kustomize edit set image controller=ligert/custom-kubernetes-operator:latest
/home/custom-kubernetes-operator/bin/kustomize build config/default | kubectl apply -f -
namespace/custom-kubernetes-operator-system created
customresourcedefinition.apiextensions.k8s.io/dummies.interview.com created
serviceaccount/custom-kubernetes-operator-controller-manager created
role.rbac.authorization.k8s.io/custom-kubernetes-operator-leader-election-role created
clusterrole.rbac.authorization.k8s.io/custom-kubernetes-operator-manager-role created
clusterrole.rbac.authorization.k8s.io/custom-kubernetes-operator-metrics-reader created
clusterrole.rbac.authorization.k8s.io/custom-kubernetes-operator-proxy-role created
rolebinding.rbac.authorization.k8s.io/custom-kubernetes-operator-leader-election-rolebinding created
clusterrolebinding.rbac.authorization.k8s.io/custom-kubernetes-operator-manager-rolebinding created
clusterrolebinding.rbac.authorization.k8s.io/custom-kubernetes-operator-proxy-rolebinding created
service/custom-kubernetes-operator-controller-manager-metrics-service created
deployment.apps/custom-kubernetes-operator-controller-manager created

To check that the deployment worked correctly, you get the deployments and the pods

$ kubectl get deploy --all-namespaces

NAMESPACE                           NAME                                            READY   UP-TO-DATE   AVAILABLE   AGE
custom-kubernetes-operator-system   custom-kubernetes-operator-controller-manager   1/1     1            1           88s

$ kubectl get pods --all-namespaces

NAMESPACE                           NAME                                                            READY   STATUS    RESTARTS         AGE
custom-kubernetes-operator-system   custom-kubernetes-operator-controller-manager-9f7fc8fbb-wg5zs   2/2     Running   0                2m10s

Creating the dummy object

To create the Dummy object, apply the sample yaml. A new pod running nginx should appear

$ kubectl apply -f config/samples/_v1alpha1_dummy.yaml 

$ kubectl get pods --all-namespaces

NAMESPACE                           NAME                                                            READY   STATUS    RESTARTS         AGE
custom-kubernetes-operator-system   custom-kubernetes-operator-controller-manager-9f7fc8fbb-wg5zs   2/2     Running   0                2m46s
default                             dummy-sample-749f6d77cc-mfrvg                                   1/1     Running   0                6s

Check Nginx pod

We can verifiy that nginx is running in the dummy-sample-* pod

kubectl logs dummy-sample-749f6d77cc-mfrvg (example)

2022/10/19 04:36:21 [notice] 1#1: using the "epoll" event method
2022/10/19 04:36:21 [notice] 1#1: nginx/1.23.1
2022/10/19 04:36:21 [notice] 1#1: built by gcc 10.2.1 20210110 (Debian 10.2.1-6) 
2022/10/19 04:36:21 [notice] 1#1: OS: Linux 5.10.16.3-microsoft-standard-WSL2
2022/10/19 04:36:21 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
2022/10/19 04:36:21 [notice] 1#1: start worker processes
2022/10/19 04:36:21 [notice] 1#1: start worker process 28
2022/10/19 04:36:21 [notice] 1#1: start worker process 29

Verify yaml

We can check the dummy yaml to verify that the spec has been copied to the status.echoSpec, and that the podStatus is correctly Running

$ kubectl get dummies.interview.com/dummy-sample -o yaml

apiVersion: interview.com/v1alpha1
kind: Dummy
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"interview.com/v1alpha1","kind":"Dummy","metadata":{"annotations":{},"name":"dummy-sample","namespace":"default"},"spec":{"message":"I'm a dummy"}}
  creationTimestamp: "2022-10-19T04:36:20Z"
  generation: 1
  name: dummy-sample
  namespace: default
  resourceVersion: "117286"
  uid: 3eb52d19-9ca1-4262-a3d7-0d416436ccd8
spec:
  message: I'm a dummy
status:
  echoSpec: I'm a dummy
  podStatus: Running

Shutting down

To stop the deployment, run these commands After executing the delete, the nginx pod associated with the dummy object will be terminated too

kubectl delete -f config/samples/_v1alpha1_dummy.yaml

NAMESPACE                           NAME                                                            READY   STATUS    RESTARTS       AGE
custom-kubernetes-operator-system   custom-kubernetes-operator-controller-manager-9f7fc8fbb-f2949   2/2     Running   0              9m3s


make undeploy

Test Results

We create the deployment and verifiy that the controller is created

make deploy

After that we can apply the dummy yaml

kubectl apply -f config/samples/_v1alpha1_dummy.yaml 

An nginx pod associated with the Dummy API will be created

The dummy name, namespace, and message are logged in the controller

The pod is running nginx

The yaml status.echoSpec and status.podStatus are correctly set to "I'm a dummy" and "Running"

Deleting the Dummy API results in the nginx pod being also terminated

make test

Unit tests are successful