「Kubernetes 官方示例：使用 Redis 部署 PHP 留言板应用程序」Operator 化。

源码仓库：https://github.com/jxlwqq/guestbook-operator

前置条件

• 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 ?=

创建项目

使用 Operator SDK CLI 创建名为 guestbook-operator 的项目。

mkdir -p $HOME/projects/guestbook-operator
cd $HOME/projects/guestbook-operator
go env -w GOPROXY=https://goproxy.cn,direct
```shell

operator-sdk init \
--domain=jxlwqq.github.io \
--repo=github.com/jxlwqq/guestbook-operator \
--skip-go-version-check

创建 API 和控制器

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 app、版本 v1alpha1 和种类 Guestbook 的 API：

operator-sdk create api \
--resource=true \
--controller=true \
--group=app \
--version=v1alpha1 \
--kind=Guestbook

定义 Guestbook 自定义资源（CR）的 API。

修改 api/v1alpha1/guestbook_types.go 中的 Go 类型定义，使其具有以下 spec 和 status

type GuestbookSpec struct {
	FrontendSize int32 `json:"frontendSize"`
	RedisFollowerSize int32 `json:"redisFollowerSize"`
}

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

实现控制器

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/guestbook_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"
	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"

	"k8s.io/apimachinery/pkg/runtime"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/log"

	appv1alpha1 "github.com/jxlwqq/guestbook-operator/api/v1alpha1"
)

// GuestbookReconciler reconciles a Guestbook object
type GuestbookReconciler struct {
	client.Client
	Scheme *runtime.Scheme
}

//+kubebuilder:rbac:groups=app.jxlwqq.github.io,resources=guestbooks,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=app.jxlwqq.github.io,resources=guestbooks/status,verbs=get;update;patch
//+kubebuilder:rbac:groups=app.jxlwqq.github.io,resources=guestbooks/finalizers,verbs=update
//+kubebuilder:rbac:groups=apps,resources=deployments,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=core,resources=service,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 Guestbook 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 *GuestbookReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	reqLogger := log.FromContext(ctx)
	reqLogger.Info("Reconciling Guestbook")

	guestbook := &appv1alpha1.Guestbook{}
	err := r.Client.Get(context.TODO(), req.NamespacedName, guestbook)
	if err != nil {
		if errors.IsNotFound(err) {
			return ctrl.Result{}, nil
		}
		return ctrl.Result{}, err
	}

	var result = &ctrl.Result{}

	result, err = r.ensureDeployment(r.redisLeaderDeployment(guestbook))
	if result != nil {
		return *result, err
	}
	result, err = r.ensureService(r.redisLeaderService(guestbook))
	if result != nil {
		return *result, err
	}

	result, err = r.ensureDeployment(r.redisFollowerDeployment(guestbook))
	if result != nil {
		return *result, err
	}
	result, err = r.ensureService(r.redisFollowerService(guestbook))
	if result != nil {
		return *result, err
	}
	result, err = r.handleRedisFollowerChanges(guestbook)
	if result != nil {
		return *result, err
	}

	result, err = r.ensureDeployment(r.frontendDeployment(guestbook))
	if result != nil {
		return *result, err
	}
	result, err = r.ensureService(r.frontendService(guestbook))
	if result != nil {
		return *result, err
	}
	result, err = r.handleFrontendChanges(guestbook)
	if result != nil {
		return *result, err
	}

	return ctrl.Result{}, nil
}

// SetupWithManager sets up the controller with the Manager.
func (r *GuestbookReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&appv1alpha1.Guestbook{}).
		Owns(&appsv1.Deployment{}).
		Owns(&corev1.Service{}).
		Complete(r)
}

运行以下命令以生成和更新 CRD 清单：

make manifests

运行 Operator

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/guestbook-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/guestbook-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/guestbook-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/guestbook-operator-bundle:v0.0.1

创建自定义资源

编辑 config/samples/app_v1alpha1_guestbook.yaml 上的 Guestbook CR 清单示例，使其包含以下规格：

apiVersion: app.jxlwqq.github.io/v1alpha1
kind: Guestbook
metadata:
  name: guestbook-sample
spec:
  # Add fields here
  frontendSize: 2
  redisFollowerSize: 2

创建 CR：

kubectl apply -f config/samples/app_v1alpha1_guestbook.yaml

查看 Pod：

NAME                              READY   STATUS    RESTARTS   AGE
frontend-85595f5bf9-jrcp4         1/1     Running   0          9s
frontend-85595f5bf9-q8fkl         1/1     Running   0          9s
redis-follower-76c5cc5b79-fxxlq   1/1     Running   0          9s
redis-follower-76c5cc5b79-g8vnf   1/1     Running   0          9s
redis-leader-6666df964-vjhp2      1/1     Running   0          9s

查看 Service：

NAME             TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
frontend         NodePort    10.106.145.169   <none>        80:30693/TCP   24s
kubernetes       ClusterIP   10.96.0.1        <none>        443/TCP        4m58s
redis-follower   ClusterIP   10.108.30.112    <none>        6379/TCP       24s
redis-leader     ClusterIP   10.106.255.152   <none>        6379/TCP       24s

浏览器访问：http://localhost:30693

网页上会显示出 Guestbook 的表单页面。

更新 CR：

# 修改frontend 和 redis 副本数
kubectl patch guestbook guestbook-sample -p '{"spec":{"frontendSize": 3, "redisFollowerSize": 3}}' --type=merge

查看 Pod：

NAME                              READY   STATUS    RESTARTS   AGE
frontend-85595f5bf9-4pmfj         1/1     Running   0          4s
frontend-85595f5bf9-jrcp4         1/1     Running   0          50s
frontend-85595f5bf9-q8fkl         1/1     Running   0          50s
redis-follower-76c5cc5b79-bxbb4   1/1     Running   0          4s
redis-follower-76c5cc5b79-fxxlq   1/1     Running   0          50s
redis-follower-76c5cc5b79-g8vnf   1/1     Running   0          50s
redis-leader-6666df964-vjhp2      1/1     Running   0          50s

做好清理

operator-sdk cleanup guestbook-operator
operator-sdk olm uninstall

更多

更多经典示例请参考：https://github.com/jxlwqq/kubernetes-examples