什么是蓝绿部署

蓝绿(blue/green)：新版本与旧版本一起存在，然后切换流量

蓝绿部署流程图

K8S中如何实现蓝绿部署

• 通过k8s service label标签来实现蓝绿发布
• 通过Ingress 控制器来实现蓝绿发布
• 通过Istio来实现蓝绿发布，或者像Istio类似的服务

这次先讲通过k8s service label标签来实现蓝绿发布，Istio实现蓝绿发布下期再分享。

k8s 蓝绿 yaml 配置

• service.yaml 文件

apiVersion: v1
kind: Service
metadata:
  name: demo
  namespace: default
  labels:
    app: demo
spec:
  ports:
    - port: 80
      targetPort: http
      protocol: TCP
      name: http
  # 注意这里我们匹配 app 和 version 标签，当要切换流量的时候，我们更新 version 标签的值，比如：v2
  selector:
    app: demo
    version: v1

• 蓝 v1-deploy.yaml 文件

apiVersion: apps/v1
kind: Deployment
metadata:
  name: demo1-deployment
  namespace: default
  labels:
    app: demo
    version: v1
spec:
  replicas: 1
  revisionHistoryLimit: 3
  strategy:
    rollingUpdate:
      maxSurge: 30%
      maxUnavailable: 30%
  selector:
    matchLabels:
      app: demo
      version: v1
  template:
    metadata:
      labels:
        app: demo
        version: v1
    spec:
      containers:
      - name: demo1
        image: mritd/demo
        livenessProbe:
          httpGet:
            path: /
            port: 80
            scheme: HTTP
          initialDelaySeconds: 30
          timeoutSeconds: 5
          periodSeconds: 30
          successThreshold: 1
          failureThreshold: 5
        readinessProbe:
          httpGet:
            path: /
            port: 80
            scheme: HTTP
          initialDelaySeconds: 30
          timeoutSeconds: 5
          periodSeconds: 10
          successThreshold: 1
          failureThreshold: 5
        ports:
          - name: http
            containerPort: 80
            protocol: TCP

• 绿 v2-deploy.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: demo2-deployment
  namespace: default
  labels:
    app: demo
    version: v2
spec:
  replicas: 1
  revisionHistoryLimit: 3
  strategy:
    rollingUpdate:
      maxSurge: 30%
      maxUnavailable: 30%
  selector:
    matchLabels:
      app: demo
      version: v2
  template:
    metadata:
      labels:
        app: demo
        version: v2
    spec:
      containers:
      - name: demo2
        image: mritd/demo
        livenessProbe:
          httpGet:
            path: /
            port: 80
            scheme: HTTP
          initialDelaySeconds: 30
          timeoutSeconds: 5
          periodSeconds: 30
          successThreshold: 1
          failureThreshold: 5
        readinessProbe:
          httpGet:
            path: /
            port: 80
            scheme: HTTP
          initialDelaySeconds: 30
          timeoutSeconds: 5
          periodSeconds: 10
          successThreshold: 1
          failureThreshold: 5
        ports:
          - name: http
            containerPort: 80
            protocol: TCP

• 上面定义的资源对象中，最重要的就是Service 中 label selector的定义：

  selector:
    app: demo
    version: v1

部署与测试

• 部署v1 v2 deploy服务 和 service服务

$ kubectl  apply -f service.yaml -f v1-deploy.yaml -f v2-deploy.yaml

• 测试流量是否到v1版本

# 登陆任意一个pod，向 demo service 发起请求
$ while sleep 0.3; do curl http://demo; done

# 输出日志
Host: demo1-deployment-b5bd596d8-dw27b, Version: v1
Host: demo1-deployment-b5bd596d8-dw27b, Version: v1

• 切换入口流量从v1 到 v2

$ kubectl patch service demo -p '{"spec":{"selector":{"version":"v2"}}}'

• 测试流量是否到v2版本

# 登陆任意一个pod，向 demo service 发起请求
$ while sleep 0.3; do curl http://demo; done

# 输出日志
Host: demo2-deployment-b5bd596d8-dw27b, Version: v2
Host: demo2-deployment-b5bd596d8-dw27b, Version: v2

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