visitors-operator 是书籍《Kubernetes Operators》的经典示例，此书著于2019年，Operator-SDK 版本迭代较快，随书的代码仓库 https://github.com/kubernetes-operators-book/chapters 已基本不可用。所以本示例基于最新版本的 Operator-SDK，做了大量的修改和调整。
- 安装 Docker Desktop，并启动内置的 Kubernetes 集群
- 注册一个 hub.docker.com 账户，需要将本地构建好的镜像推送至公开仓库中
- 安装 operator SDK CLI:
brew install operator-sdk - 安装 Go:
brew install go
本示例推荐的依赖版本：
- Docker Desktop: >= 4.0.0
- Kubernetes: >= 1.21.4
- Operator-SDK: >= 1.11.0
- Go: >= 1.17
jxlwqq 为笔者的 ID，命令行和代码中涉及的个人 ID，均需要替换为读者自己的，包括
--domain=--repo=//+kubebuilder:rbac:groups=IMAGE_TAG_BASE ?=
使用 Operator SDK CLI 创建名为 visitors-operator 的项目。
mkdir -p $HOME/projects/visitors-operator
cd $HOME/projects/visitors-operator
go env -w GOPROXY=https://goproxy.cn,direct
operator-sdk init \
--domain=jxlwqq.github.io \
--repo=github.com/jxlwqq/visitors-operator \
--skip-go-version-check使用 Operator SDK CLI 创建自定义资源定义（CRD）API 和控制器。
运行以下命令创建带有组 cache、版本 v1alpha1 和种类 VisitorsApp 的 API：
operator-sdk create api \
--resource=true \
--controller=true \
--group=app \
--version=v1alpha1 \
--kind=VisitorsApp定义 VisitorsApp 自定义资源（CR）的 API。
修改 api/v1alpha1/visitorsapp_types.go 中的 Go 类型定义，使其具有以下 spec 和 status
type VisitorsAppSpec struct {
Size int32 `json:"size"`
Title string `json:"title"`
}
type VisitorsAppStatus struct {
BackendImage string `json:"backend_image"`
FrontendImage string `json:"frontend_image"`
}为资源类型更新生成的代码：
make generate运行以下命令以生成和更新 CRD 清单：
make manifests由于逻辑较为复杂，代码较为庞大，所以无法在此全部展示，完整的操作器代码请参见 controllers 目录。
在本例中，将生成的控制器文件 controllers/visitors_controller.go 替换为以下示例实现：
/*
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 (
"context"
"fmt"
appsv1 "k8s.io/api/apps/v1"
corev1 "k8s.io/api/core/v1"
"k8s.io/apimachinery/pkg/api/errors"
"time"
"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"
appv1alpha1 "github.com/jxlwqq/visitors-operator/api/v1alpha1"
)
// VisitorsAppReconciler reconciles a VisitorsApp object
type VisitorsAppReconciler struct {
client.Client
Scheme *runtime.Scheme
}
//+kubebuilder:rbac:groups=app.jxlwqq.github.io,resources=visitorsapps,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=app.jxlwqq.github.io,resources=visitorsapps/status,verbs=get;update;patch
//+kubebuilder:rbac:groups=app.jxlwqq.github.io,resources=visitorsapps/finalizers,verbs=update
//+kubebuilder:rbac:groups=apps,resources=deployments,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=core,resources=services,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=core,resources=secrets,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 VisitorsApp 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/[email protected]/pkg/reconcile
func (r *VisitorsAppReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
log := ctrllog.FromContext(ctx)
reqLogger := log.WithValues("Request.Namespace", req.Namespace, "Request.Name", req.Name)
reqLogger.Info("Reconciling VisitorsApp")
// Fetch the VisitorsApp instance
v := &appv1alpha1.VisitorsApp{}
err := r.Client.Get(context.TODO(), req.NamespacedName, v)
if err != nil {
if errors.IsNotFound(err) {
return ctrl.Result{}, nil
}
return ctrl.Result{}, err
}
var result *ctrl.Result
// Database
result, err = r.ensureSecret(r.mysqlAuthSecret(v))
if result != nil {
return *result, err
}
result, err = r.ensureDeployment(r.mysqlDeployment(v))
if result != nil {
return *result, err
}
result, err = r.ensureService(r.mysqlService(v))
if result != nil {
return *result, err
}
if !r.isMysqlUp(v) {
delay := time.Second * time.Duration(5)
log.Info(fmt.Sprintf("MySQL isn't running, waiting for %s", delay))
return ctrl.Result{RequeueAfter: delay}, nil
}
// Backend
result, err = r.ensureDeployment(r.backendDeployment(v))
if result != nil {
return *result, err
}
result, err = r.ensureService(r.backendService(v))
if result != nil {
return *result, err
}
err = r.updateBackendStatus(v)
if err != nil {
return ctrl.Result{}, err
}
result, err = r.handleBackendChanges(v)
if result != nil {
return *result, err
}
// Frontend
result, err = r.ensureDeployment(r.frontendDeployment(v))
if result != nil {
return *result, err
}
result, err = r.ensureService(r.frontendService(v))
if result != nil {
return *result, err
}
err = r.updateFrontendStatus(v)
if err != nil {
return ctrl.Result{}, err
}
result, err = r.handleFrontendChanges(v)
if result != nil {
return *result, err
}
return ctrl.Result{}, nil
}
// SetupWithManager sets up the controller with the Manager.
func (r *VisitorsAppReconciler) SetupWithManager(mgr ctrl.Manager) error {
return ctrl.NewControllerManagedBy(mgr).
For(&appv1alpha1.VisitorsApp{}).
Owns(&appsv1.Deployment{}).
Owns(&corev1.Service{}).
Owns(&corev1.Secret{}).
Complete(r)
}运行以下命令以生成和更新 CRD 清单：
make manifests捆绑 Operator，并使用 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/visitors-operator
IMG ?= $(IMAGE_TAG_BASE):latest构建镜像：
make docker-build将镜像推送到镜像仓库：
make docker-push成功后访问：https://hub.docker.com/r/jxlwqq/visitors-operator
运行 make bundle 命令创建 Operator 捆绑包清单，并依次填入名称、作者等必要信息:
make bundle构建捆绑包镜像：
make bundle-build推送捆绑包镜像：
make bundle-push成功后访问：https://hub.docker.com/r/jxlwqq/visitors-operator-bundle
使用 Operator Lifecycle Manager 部署 Operator:
# 切换至本地集群
kubectl config use-context docker-desktop
# 安装 olm
operator-sdk olm install
# 使用 Operator SDK 中的 OLM 集成在集群中运行 Operator
operator-sdk run bundle docker.io/jxlwqq/visitors-operator-bundle:v0.0.1编辑 config/samples/app_v1alpha1_visitorsapp.yaml 上的 VisitorsApp CR 清单示例，使其包含以下规格：
apiVersion: app.jxlwqq.github.io/v1alpha1
kind: VisitorsApp
metadata:
name: visitorsapp-sample
spec:
# Add fields here
size: 1
title: Hello创建 CR：
kubectl apply -f config/samples/app_v1alpha1_visitorsapp.yaml查看 Pod：
NAME READY STATUS RESTARTS AGE
mysql-bbdc8b45f-mxt4l 1/1 Running 0 11s
visitorsapp-sample-backend-5f954fcc56-mm8bp 1/1 Running 0 11s
visitorsapp-sample-frontend-6b666b55c7-hl4ch 1/1 Running 0 11s查看 Service：
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 18h
mysql-svc ClusterIP None <none> 3306/TCP 52s
visitorsapp-sample-backend-svc NodePort 10.105.131.165 <none> 8000:30685/TCP 52s
visitorsapp-sample-frontend-svc NodePort 10.99.93.124 <none> 3000:30686/TCP 52s浏览器访问：http://localhost:30686
网页上会显示以下内容，记录了访问者的访问记录：
Hello
Service IP Client IP Timestamp
10.1.1.108 192.168.65.3 2021/9/10 上午11:06:40
10.1.1.108 192.168.65.3 2021/9/10 上午11:06:38
operator-sdk cleanup visitors-operator
operator-sdk olm uninstall更多经典示例请参考：https://github.com/jxlwqq/kubernetes-examples