最简单的 K8S 部署文件编写姿势，没有之一！

1. 头疼编写K8S部署文件？

• K8S yaml 参数很多，需要边写边查？
• 保留回滚版本数怎么设？
• 如何探测启动成功，如何探活？
• 如何分配和限制资源？
• 如何设置时区？否则打印日志是GMT标准时间
• 如何暴露服务供其它服务调用？
• 如何根据CPU和内存使用率来配置水平伸缩？

首先，你需要知道有这些知识点，其次要把这些知识点都搞明白也不容易，再次，每次编写依然容易出错！

2. 创建服务镜像

前一篇文章 讲解了如何快速创建自己的服务镜像，不过为了演示，这篇文章我们以 redis:6-alpine 镜像为例。

3. 完整K8S部署文件编写过程

• 首先安装 goctl 工具

  GO111MODULE=on GOPROXY=https://goproxy.cn/,direct go get -u github.com/tal-tech/go-zero/tools/goctl

• 一键生成K8S部署文件

  goctl kube deploy -name redis -namespace adhoc -image redis:6-alpine -o redis.yaml -port 6379

  生成的 yaml 文件如下：

  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: redis
    namespace: adhoc
    labels:
      app: redis
  spec:
    replicas: 3
    revisionHistoryLimit: 5
    selector:
      matchLabels:
        app: redis
    template:
      metadata:
        labels:
          app: redis
      spec:
        containers:
        - name: redis
          image: redis:6-alpine
          lifecycle:
            preStop:
              exec:
                command: ["sh","-c","sleep 5"]
          ports:
          - containerPort: 6379
          readinessProbe:
            tcpSocket:
              port: 6379
            initialDelaySeconds: 5
            periodSeconds: 10
          livenessProbe:
            tcpSocket:
              port: 6379
            initialDelaySeconds: 15
            periodSeconds: 20
          resources:
            requests:
              cpu: 500m
              memory: 512Mi
            limits:
              cpu: 1000m
              memory: 1024Mi
          volumeMounts:
          - name: timezone
            mountPath: /etc/localtime
        volumes:
          - name: timezone
            hostPath:
              path: /usr/share/zoneinfo/Asia/Shanghai
  
  ---
  
  apiVersion: v1
  kind: Service
  metadata:
    name: redis-svc
    namespace: adhoc
  spec:
    ports:
      - port: 6379
    selector:
      app: redis
  
  ---
  
  apiVersion: autoscaling/v2beta1
  kind: HorizontalPodAutoscaler
  metadata:
    name: redis-hpa-c
    namespace: adhoc
    labels:
      app: redis-hpa-c
  spec:
    scaleTargetRef:
      apiVersion: apps/v1
      kind: Deployment
      name: redis
    minReplicas: 3
    maxReplicas: 10
    metrics:
    - type: Resource
      resource:
        name: cpu
        targetAverageUtilization: 80
  
  ---
  
  apiVersion: autoscaling/v2beta1
  kind: HorizontalPodAutoscaler
  metadata:
    name: redis-hpa-m
    namespace: adhoc
    labels:
      app: redis-hpa-m
  spec:
    scaleTargetRef:
      apiVersion: apps/v1
      kind: Deployment
      name: redis
    minReplicas: 3
    maxReplicas: 10
    metrics:
    - type: Resource
      resource:
        name: memory
        targetAverageUtilization: 80
  

• 部署服务，如果 adhoc namespace不存在的话，请先通过 kubectl create namespace adhoc 创建

  $ kubectl apply -f redis.yaml
  deployment.apps/redis created
  service/redis-svc created
  horizontalpodautoscaler.autoscaling/redis-hpa-c created
  horizontalpodautoscaler.autoscaling/redis-hpa-m created
  

• 查看服务允许状态

  $ kubectl get all -n adhoc
  NAME                         READY   STATUS    RESTARTS   AGE
  pod/redis-585bc66876-5ph26   1/1     Running   0          6m5s
  pod/redis-585bc66876-bfqxz   1/1     Running   0          6m5s
  pod/redis-585bc66876-vvfc9   1/1     Running   0          6m5s
  
  NAME                TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)    AGE
  service/redis-svc   ClusterIP   172.24.15.8   <none>        6379/TCP   6m5s
  
  NAME                    READY   UP-TO-DATE   AVAILABLE   AGE
  deployment.apps/redis   3/3     3            3           6m6s
  
  NAME                               DESIRED   CURRENT   READY   AGE
  replicaset.apps/redis-585bc66876   3         3         3       6m6s
  
  NAME                                              REFERENCE          TARGETS   MINPODS   MAXPODS   REPLICAS   AGE
  horizontalpodautoscaler.autoscaling/redis-hpa-c   Deployment/redis   0%/80%    3         10        3          6m6s
  horizontalpodautoscaler.autoscaling/redis-hpa-m   Deployment/redis   0%/80%    3         10        3          6m6s
  

• 测试服务

  $ kubectl run -i --tty --rm cli --image=redis:6-alpine -n adhoc -- sh
  /data # redis-cli -h redis-svc
  redis-svc:6379> set go-zero great
  OK
  redis-svc:6379> get go-zero
  "great"
  

4. 总结

goctl 工具极大简化了 K8S yaml 文件的编写，提供了开箱即用的最佳实践，并且支持了模板自定义。

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