Operator SDK 中的 Go 編程語言支持可以利用 Operator SDK 中的 Go 編程語言支持，為 Memcached 構
建基於 Go 的 Operator 示例、分布式鍵值存儲並管理其生命周期。
github: https://github.com/jxlwqq/memcached-operator
前置條件
- 安裝 Docker Desktop，並啟動內置的 Kubernetes 集群
- 注冊一個 hub.docker.com 賬戶，需要將本地構建好的鏡像推送至公開倉庫中
- 安裝 operator SDK CLI:
brew install operator-sdk - 安裝 Go:
brew install go
創建項目
使用 Operator SDK CLI 創建名為 memcached-operator 的項目。
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
創建 API 和控制器
使用 Operator SDK CLI 創建自定義資源定義（CRD）API 和控制器。
運行以下命令創建帶有組 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 類型定義，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"`
}
為資源類型更新生成的代碼：
make generate
運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，將生成的控制器文件 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)
}
運行以下命令以生成和更新 CRD 清單：
make manifests
運行 Operator
捆綁 Operator，並使用 Operator Lifecycle Manager（OLM）在集群中部署。
修改 Makefile 中 IMAGE_TAG_BASE 和 IMG：
IMAGE_TAG_BASE ?= docker.io/jxlwqq/memcached-operator
IMG ?= $(IMAGE_TAG_BASE):latest
構建鏡像：
make docker-build
將鏡像推送到鏡像倉庫：
make docker-push
成功后訪問：https://hub.docker.com/r/jxlwqq/memcached-operator
運行 make bundle 命令創建 Operator 捆綁包清單，並依次填入名稱、作者等必要信息:
make bundle
構建捆綁包鏡像：
make bundle-build
推送捆綁包鏡像：
make bundle-push
成功后訪問：https://hub.docker.com/r/jxlwqq/memcached-operator-bundle
使用 Operator Lifecycle Manager 部署 Operator:
# 切換至本地集群
kubectl config use-context docker-desktop
# 安裝 olm
operator-sdk olm install
# 使用 Operator SDK 中的 OLM 集成在集群中運行 Operator
operator-sdk run bundle docker.io/jxlwqq/memcached-operator-bundle:v0.0.1
查看 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
創建自定義資源
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
創建 CR：
kubectl apply -f config/samples/cache_v1alpha1_memcached.yaml
查看 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
查看 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