Operator SDK 中的 Go 程式語言支援可以利用 Operator SDK 中的 Go 程式語言支援，為 Memcached 構
建基於 Go 的 Operator 示例、分散式鍵值儲存並管理其生命週期。
github: github.com/jxlwqq/memcached-operat...
前置條件
- 安裝 Docker Desktop，並啟動內建的 Kubernetes 叢集
- 註冊一個 hub.docker.com 賬戶，需要將本地構建好的映象推送至公開倉庫中
- 安裝 operator SDK CLI:
brew install operator-sdk - 安裝 Go:
brew install go
建立專案
使用 Operator SDK CLI 建立名為 memcached-operator 的專案。
mkdir -p $HOME/projects/memcached-operator
cd $HOME/projects/memcached-operator
go env -w GOPROXY=https://goproxy.cn,direct
operator-sdk init \
--domain=jxlwqq.github.io \
--repo=github.com/jxlwqq/memcached-operator \
--skip-go-version-check建立 API 和控制器
使用 Operator SDK CLI 建立自定義資源定義（CRD）API 和控制器。
執行以下命令建立帶有組 cache、版本 v1alpha1 和種類 Memcached 的 API：
operator-sdk create api \
--resource=true \
--controller=true \
--group=cache \
--version=v1alpha1 \
--kind=Memcached定義 Memcached 自定義資源（CR）的 API。
修改 api/v1alpha1/memcached_types.go 中的 Go 型別定義，使其具有以下 spec 和 status
type MemcachedSpec struct {
// +kubebuilder:validation:Minimum=0
// Size is the size of the memcached deployment
Size int32 `json:"size"`
}
type MemcachedStatus struct {
// Nodes are the names of the memcached pods
Nodes []string `json:"nodes"`
}為資源型別更新生成的程式碼：
make generate執行以下命令以生成和更新 CRD 清單：
make manifests實現控制器
在本例中，將生成的控制器檔案 controllers/memcached_controller.go 替換為以下示例實現：
/*
Copyright 2021.
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"
"time"
"context"
"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"
cachev1alpha1 "github.com/jxlwqq/memcached-operator/api/v1alpha1"
)
// MemcachedReconciler reconciles a Memcached object
type MemcachedReconciler struct {
client.Client
Scheme *runtime.Scheme
}
//+kubebuilder:rbac:groups=cache.jxlwqq.github.io,resources=memcacheds,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=cache.jxlwqq.github.io,resources=memcacheds/status,verbs=get;update;patch
//+kubebuilder:rbac:groups=cache.jxlwqq.github.io,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;watch
// 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@v0.9.2/pkg/reconcile
func (r *MemcachedReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
log := ctrllog.FromContext(ctx)
// Fetch the Memcached instance
memcached := &cachev1alpha1.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
}
// Ask to requeue after 1 minute in order to give enough time for the
// pods be created on the cluster side and the operand be able
// to do the next update step accurately.
return ctrl.Result{RequeueAfter: time.Minute}, 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 *cachev1alpha1.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(&cachev1alpha1.Memcached{}).
Owns(&appsv1.Deployment{}).
Complete(r)
}執行以下命令以生成和更新 CRD 清單：
make manifests執行 Operator
捆綁 Operator，並使用 Operator Lifecycle Manager（OLM）在叢集中部署。
修改 Makefile 中 IMAGE_TAG_BASE 和 IMG：
IMAGE_TAG_BASE ?= docker.io/jxlwqq/memcached-operator
IMG ?= $(IMAGE_TAG_BASE):latest構建映象：
make docker-build將映象推送到映象倉庫：
make docker-push成功後訪問：hub.docker.com/r/jxlwqq/memcached-...
執行 make bundle 命令建立 Operator 捆綁包清單，並依次填入名稱、作者等必要資訊:
make bundle構建捆綁包映象：
make bundle-build推送捆綁包映象：
make bundle-push成功後訪問：hub.docker.com/r/jxlwqq/memcached-...
使用 Operator Lifecycle Manager 部署 Operator:
# 切換至本地叢集
kubectl config use-context docker-desktop
# 安裝 olm
operator-sdk olm install
# 使用 Operator SDK 中的 OLM 整合在叢集中執行 Operator
operator-sdk run bundle docker.io/jxlwqq/memcached-operator-bundle:v0.0.1檢視 Pod：
NAME READY STATUS RESTARTS AGE
7bb60cfcec4a426a75d6ca01153f5e6d3061e175d035791255372bdd7ebrvmd 0/1 Completed 0 67s
docker-io-jxlwqq-memcached-operator-bundle-v0-0-1 1/1 Running 0 84s
memcached-operator-controller-manager-666cfff6c-fxhrk 2/2 Running 0 41s建立自定義資源
編輯 config/samples/cache_v1alpha1_memcached.yaml 上的 Memcached CR 清單示例，使其包含
以下規格：
apiVersion: cache.jxlwqq.github.io/v1alpha1
kind: Memcached
metadata:
name: memcached-sample
spec:
size: 2建立 CR：
kubectl apply -f config/samples/cache_v1alpha1_memcached.yaml檢視 Pod：
NAME READY STATUS RESTARTS AGE
7bb60cfcec4a426a75d6ca01153f5e6d3061e175d035791255372bdd7ebrvmd 0/1 Completed 0 4m14s
docker-io-jxlwqq-memcached-operator-bundle-v0-0-1 1/1 Running 0 4m31s
memcached-operator-controller-manager-666cfff6c-fxhrk 2/2 Running 0 3m48s
memcached-sample-6c765df685-d8ppn 1/1 Running 0 29s
memcached-sample-6c765df685-dtw9l 1/1 Running 0 29s更新 CR：
kubectl patch memcached memcached-sample -p '{"spec":{"size": 3}}' --type=merge檢視 Pod：
NAME READY STATUS RESTARTS AGE
7bb60cfcec4a426a75d6ca01153f5e6d3061e175d035791255372bdd7ebrvmd 0/1 Completed 0 6m52s
docker-io-jxlwqq-memcached-operator-bundle-v0-0-1 1/1 Running 0 7m9s
memcached-operator-controller-manager-666cfff6c-fxhrk 2/2 Running 0 6m26s
memcached-sample-6c765df685-d8ppn 1/1 Running 0 3m7s
memcached-sample-6c765df685-dtw9l 1/1 Running 0 3m7s
memcached-sample-6c765df685-n7ctq 1/1 Running 0 6s做好清理
operator-sdk cleanup memcached-operator
operator-sdk olm uninstall本作品採用《CC 協議》，轉載必須註明作者和本文連結