Operators Hands On

3 minute read

Overview

In this demo, we will build a GO-based Operator called Cloner. The project name is openinfra-summit. kind is kind: Cloner

Goal

Create a simple Go-based Operator where the custom resource for the application is Kind: Cloner. Cloner is a simple nignx based application.

Overview

  • Create a project called openinfra-summit using the operator-sdk command line.

  • The main program for the operator is cmd/manager/main.go that initializes and runs the Manager. The Manager will automatically register the scheme for all CR defined under pkg/apis/... and run all controllers under pkg/controller/...

  • Add a new CRD API called Cloner, with APIVersion kubedge.cloud.com/v1alpha1 and Kind: Cloner using the operator-sdk command line.

  • Update pkg/apis/kubedge/v1alpha1/cloner_types.go as required with custom Specs and Status to deploy our application Cloner. After updating cloner_types.go run operator-sdk generate k8s and operator-sdk generate openapi to update the generated code for that resource type.

  • Add a new Controller for our project openinfra-summit which watches and reconciles the Cloner resource, this is done using the operator-sdk command line. This will scaffold a new Controller implementation under pkg/controller/cloner/.

  • Register our new CRD with Kubernetes APIServer.

  • Setup RBAC and deploy openinfra-summit.

  • Deploy our new CR or application called Cloner.

Getting Started

Login to server with username summit and password as summit.

ssh summit@IPADRESS

Naviagte to /home/summit/src

cd /home/summit/src

Steps to Execute

  1. Step1 implements,

    1. Executes operator-sdk new openinfra-summit command to create a new Project called openinfra-summit.

    2. Executes go mod tidy from the folder the openinfra-summit folder to install all dependencies required for GO.

      ./operator.sh step1

  2. Step2 implements,

    1. Executes operator-sdk add api --api-version=kubedge.cloud.com/v1alpha1 --kind=Cloner to add a new Custom Resource Definition API called Cloner with APIVersion kubedge.cloud.com/v1alpha1 and Kind Cloner.
    2. Modifies pkg/apis/kubedge/v1alpha1/cloner_types.go to define new fields for Cloner spec and status.
    3. Executes operator-sdk generate k8s after modifying the cloner_types.go file to update the generated code for that resource type.

    4. Executes operator-sdk generate openapi to automatically generate the OpenAPI validations.

      ./operator.sh step2

  3. Step3 implements,

    1. Executes operator-sdk add controller --api-version=kubedge.cloud.com/v1alpha1 --kind=Cloner to add a new Controller to the project that will watch and reconcile the Cloner resource.
    2. Execute kubectl create -f deploy/crds/kubedge_v1alpha1_cloner_crd.yaml to register the CRD with Kubernetes apiserver.

    3. Update deploy/operator.yaml with openinfra-summit image.

      ./operator.sh step3

  4. Step4 implements,

    1. Creates Service Account by executing kubectl create -f deploy/service_account.yaml.
    2. Creates Role by executing kubectl create -f deploy/role.yaml.
    3. Creates RoleBinding Account by executing kubectl create -f deploy/role_binding.yaml.

    4. Deploy openinfra-summit Controller kubectl create -f deploy/operator.yaml.

      ./operator.sh step4

Verify that the openinfra-summit Deployment is up and running:

kubectl get deployment
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
openinfra-summit   1/1     1            1           29m

  1. Step5 implements,

    1. Update the CR to match with the latest template Spec.

    2. Create the Cloner CR that was generated at kubectl apply -f deploy/crds/kubedge_v1alpha1_cloner_cr.yaml

      ./operator.sh step5

Check if the pods and CR status to confirm the status is updated with the Cloner pod names

kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
summit-cloner-pod                   1/1     Running   0          7s
openinfra-summit-5f5d76564d-f45tx   1/1     Running   0          25s

Check our newly created operator called Cloner

kubectl get cloner
NAME            AGE
summit-cloner   10s
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