5.3. Go 기반 Operator

• Operator SDK CLI가 설치됨
• OpenShift CLI (oc) 4 이상이 설치됨
• Go 1.19 이상
• dedicated-admin 권한이 있는 계정으로 oc 를 사용하여 AWS 클러스터의 Red Hat OpenShift Service에 로그인
• 클러스터가 이미지를 가져올 수 있도록 하려면 이미지를 내보내는 리포지토리를 공개로 설정하거나 이미지 가져오기 보안을 구성해야 합니다.

프로세스

• 이 예제에서는 생성된 컨트롤러 파일 controllers/memcached_controller.go를 다음 예제 구현으로 교체합니다.

  예 5.1. memcached_controller.go의 예

  /*
  Copyright 2020.
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
      http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  */
  
  package controllers
  
  import (
          appsv1 "k8s.io/api/apps/v1"
          corev1 "k8s.io/api/core/v1"
          "k8s.io/apimachinery/pkg/api/errors"
          metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
          "k8s.io/apimachinery/pkg/types"
          "reflect"
  
          "context"
  
          "github.com/go-logr/logr"
          "k8s.io/apimachinery/pkg/runtime"
          ctrl "sigs.k8s.io/controller-runtime"
          "sigs.k8s.io/controller-runtime/pkg/client"
          ctrllog "sigs.k8s.io/controller-runtime/pkg/log"
  
          cachev1 "github.com/example-inc/memcached-operator/api/v1"
  )
  
  // MemcachedReconciler reconciles a Memcached object
  type MemcachedReconciler struct {
          client.Client
          Log    logr.Logger
          Scheme *runtime.Scheme
  }
  
  // +kubebuilder:rbac:groups=cache.example.com,resources=memcacheds,verbs=get;list;watch;create;update;patch;delete
  // +kubebuilder:rbac:groups=cache.example.com,resources=memcacheds/status,verbs=get;update;patch
  // +kubebuilder:rbac:groups=cache.example.com,resources=memcacheds/finalizers,verbs=update
  // +kubebuilder:rbac:groups=apps,resources=deployments,verbs=get;list;watch;create;update;patch;delete
  // +kubebuilder:rbac:groups=core,resources=pods,verbs=get;list;
  
  // Reconcile is part of the main kubernetes reconciliation loop which aims to
  // move the current state of the cluster closer to the desired state.
  // TODO(user): Modify the Reconcile function to compare the state specified by
  // the Memcached object against the actual cluster state, and then
  // perform operations to make the cluster state reflect the state specified by
  // the user.
  //
  // For more details, check Reconcile and its Result here:
  // - https://pkg.go.dev/sigs.k8s.io/controller-runtime@v0.7.0/pkg/reconcile
  func (r *MemcachedReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
          //log := r.Log.WithValues("memcached", req.NamespacedName)
          log := ctrllog.FromContext(ctx)
          // Fetch the Memcached instance
          memcached := &cachev1.Memcached{}
          err := r.Get(ctx, req.NamespacedName, memcached)
          if err != nil {
                  if errors.IsNotFound(err) {
                          // Request object not found, could have been deleted after reconcile request.
                          // Owned objects are automatically garbage collected. For additional cleanup logic use finalizers.
                          // Return and don't requeue
                          log.Info("Memcached resource not found. Ignoring since object must be deleted")
                          return ctrl.Result{}, nil
                  }
                  // Error reading the object - requeue the request.
                  log.Error(err, "Failed to get Memcached")
                  return ctrl.Result{}, err
          }
  
          // Check if the deployment already exists, if not create a new one
          found := &appsv1.Deployment{}
          err = r.Get(ctx, types.NamespacedName{Name: memcached.Name, Namespace: memcached.Namespace}, found)
          if err != nil && errors.IsNotFound(err) {
                  // Define a new deployment
                  dep := r.deploymentForMemcached(memcached)
                  log.Info("Creating a new Deployment", "Deployment.Namespace", dep.Namespace, "Deployment.Name", dep.Name)
                  err = r.Create(ctx, dep)
                  if err != nil {
                          log.Error(err, "Failed to create new Deployment", "Deployment.Namespace", dep.Namespace, "Deployment.Name", dep.Name)
                          return ctrl.Result{}, err
                  }
                  // Deployment created successfully - return and requeue
                  return ctrl.Result{Requeue: true}, nil
          } else if err != nil {
                  log.Error(err, "Failed to get Deployment")
                  return ctrl.Result{}, err
          }
  
          // Ensure the deployment size is the same as the spec
          size := memcached.Spec.Size
          if *found.Spec.Replicas != size {
                  found.Spec.Replicas = &size
                  err = r.Update(ctx, found)
                  if err != nil {
                          log.Error(err, "Failed to update Deployment", "Deployment.Namespace", found.Namespace, "Deployment.Name", found.Name)
                          return ctrl.Result{}, err
                  }
                  // Spec updated - return and requeue
                  return ctrl.Result{Requeue: true}, nil
          }
  
          // Update the Memcached status with the pod names
          // List the pods for this memcached's deployment
          podList := &corev1.PodList{}
          listOpts := []client.ListOption{
                  client.InNamespace(memcached.Namespace),
                  client.MatchingLabels(labelsForMemcached(memcached.Name)),
          }
          if err = r.List(ctx, podList, listOpts...); err != nil {
                  log.Error(err, "Failed to list pods", "Memcached.Namespace", memcached.Namespace, "Memcached.Name", memcached.Name)
                  return ctrl.Result{}, err
          }
          podNames := getPodNames(podList.Items)
  
          // Update status.Nodes if needed
          if !reflect.DeepEqual(podNames, memcached.Status.Nodes) {
                  memcached.Status.Nodes = podNames
                  err := r.Status().Update(ctx, memcached)
                  if err != nil {
                          log.Error(err, "Failed to update Memcached status")
                          return ctrl.Result{}, err
                  }
          }
  
          return ctrl.Result{}, nil
  }
  
  // deploymentForMemcached returns a memcached Deployment object
  func (r *MemcachedReconciler) deploymentForMemcached(m *cachev1.Memcached) *appsv1.Deployment {
          ls := labelsForMemcached(m.Name)
          replicas := m.Spec.Size
  
          dep := &appsv1.Deployment{
                  ObjectMeta: metav1.ObjectMeta{
                          Name:      m.Name,
                          Namespace: m.Namespace,
                  },
                  Spec: appsv1.DeploymentSpec{
                          Replicas: &replicas,
                          Selector: &metav1.LabelSelector{
                                  MatchLabels: ls,
                          },
                          Template: corev1.PodTemplateSpec{
                                  ObjectMeta: metav1.ObjectMeta{
                                          Labels: ls,
                                  },
                                  Spec: corev1.PodSpec{
                                          Containers: []corev1.Container{{
                                                  Image:   "memcached:1.4.36-alpine",
                                                  Name:    "memcached",
                                                  Command: []string{"memcached", "-m=64", "-o", "modern", "-v"},
                                                  Ports: []corev1.ContainerPort{{
                                                          ContainerPort: 11211,
                                                          Name:          "memcached",
                                                  }},
                                          }},
                                  },
                          },
                  },
          }
          // Set Memcached instance as the owner and controller
          ctrl.SetControllerReference(m, dep, r.Scheme)
          return dep
  }
  
  // labelsForMemcached returns the labels for selecting the resources
  // belonging to the given memcached CR name.
  func labelsForMemcached(name string) map[string]string {
          return map[string]string{"app": "memcached", "memcached_cr": name}
  }
  
  // getPodNames returns the pod names of the array of pods passed in
  func getPodNames(pods []corev1.Pod) []string {
          var podNames []string
          for _, pod := range pods {
                  podNames = append(podNames, pod.Name)
          }
          return podNames
  }
  
  // SetupWithManager sets up the controller with the Manager.
  func (r *MemcachedReconciler) SetupWithManager(mgr ctrl.Manager) error {
          return ctrl.NewControllerManagedBy(mgr).
                  For(&cachev1.Memcached{}).
                  Owns(&appsv1.Deployment{}).
                  Complete(r)
  }

  예제 컨트롤러는 각 Memcached CR(사용자 정의 리소스)에 대해 다음 조정 논리를 실행합니다.

  • Memcached 배포가 없는 경우 생성합니다.
  • 배포 크기가 Memcached CR 사양에 지정된 것과 같은지 확인합니다.
  • Memcached CR 상태를 memcached Pod의 이름으로 업데이트합니다.

• HTTP_PROXY
• HTTPS_PROXY
• NO_PROXY

사전 요구 사항

• 클러스터 전체 egress 프록시가 활성화된 클러스터입니다.

사전 요구 사항

• Memcached CR을 제공하는 Memcached Operator의 예가 클러스터에 설치됨

사전 요구 사항

• Operator SDK 1.31.0이 설치됨
• Operator SDK 1.28.0을 사용하여 생성되거나 유지 관리되는 Operator 프로젝트

프로세스

• 다음 예와 같이 Operator 프로젝트의 makefile을 편집하여 Operator SDK 버전을 1.31.0으로 업데이트합니다.

  makefile의 예

  # Set the Operator SDK version to use. By default, what is installed on the system is used.
  # This is useful for CI or a project to utilize a specific version of the operator-sdk toolkit.
  OPERATOR_SDK_VERSION ?= v1.31.0 1

  1

  버전을 1.28.0 에서 1.31.0 으로 변경합니다.