《kubernetes权威指南第四版》mysql-tomcat集

原书出版于2019年6月，但版本仍较低，案例也较为过时，本文针对k8s v1.18；原书案例坑较多，本文加以修正。

一. Deployment of mysql

1. 文件名：mysql-deploy.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
       - name: mysql
         image: mysql:5.7
         ports:
         - containerPort: 3306
         env:
         - name: MYSQL_ROOT_PASSWORD
           value: "123456"

2. 更改的内容如下：

• kind 由原ReplicationController变化为Deployment，相应的apiVersion也变为apps/v1，同时selector也变为matchLabels。
• image变为mysql:5.7 否则在连接时会出现事务异常（mysql:lastest镜像是8）

3. 启动：

kubectl create -f mysql-deploy.yaml

二、Service of mysql

1. 文件名：mysql-svc.yaml

apiVersion: v1
kind: Service
metadata:
  name: mysql
spec:
  ports:
    - port: 3306
  selector:
    app: mysql

2. 说明如下：

• selector会选择由mysql-deploy.yaml->template->labels创造的标签名为app:mysql的pod。

3. 启动

kubectl create -f mysql-svc.yaml

三、Deployment of myweb

1. 文件名：myweb-deploy.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myweb
spec:
  replicas: 2
  selector:
    matchLabels:
      app: myweb
  template:
    metadata:
      labels:
        app: myweb
    spec:
      containers:
        - name: myweb
          image: kubeguide/tomcat-app:v1
          ports:
            - containerPort: 8080
          env:
            - name: MYSQL_SERVICE_NAME
              value: "mysql"

2. 更改的内容如下：

• kind 由原ReplicationController变化为Deployment，相应的apiVersion也变为apps/v1，同时selector也变为matchLabels。
• env 添加一个环境变量MYSQL_SERVICE_NAME，指向到mysql-svc.yaml中的metadata->name上（原书将未设置此项，采用了Service的默认IP，此坑较深）。

3. 运行：

kubectl create -f myweb-deploy.yaml

四、Service of myweb

1. 文件名：myweb-svc.yaml

apiVersion: v1
kind: Service
metadata:
  name: myweb
spec:
  type: NodePort
  ports:
    - port: 8080
      nodePort: 30001
  selector:
    app: myweb

2. 运行：

kubectl create -f mysql-svc.yaml

五、复位脚本：

#!/bin/bash
kubectl delete -f mysql-svc.yaml
kubectl delete -f mysql-deploy.yaml
kubectl delete -f myweb-svc.yaml
kubectl delete -f myweb-deploy.yaml

kubectl create -f mysql-deploy.yaml
kubectl create -f mysql-svc.yaml
kubectl create -f myweb-deploy.yaml
kubectl create -f myweb-svc.yaml

六、汇总到一起

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
       - name: mysql
         image: mysql:5.7
         ports:
         - containerPort: 3306
         env:
         - name: MYSQL_ROOT_PASSWORD
           value: "123456"
---
apiVersion: v1
kind: Service
metadata:
  name: mysql
spec:
  ports:
    - port: 3306
  selector:
    app: mysql
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myweb
spec:
  replicas: 2
  selector:
    matchLabels:
      app: myweb
  template:
    metadata:
      labels:
        app: myweb
    spec:
      containers:
        - name: myweb
          image: kubeguide/tomcat-app:v1
          ports:
            - containerPort: 8080
          env:
            - name: MYSQL_SERVICE_NAME
              value: "mysql"
---
apiVersion: v1
kind: Service
metadata:
  name: myweb
spec:
  type: NodePort
  ports:
    - port: 8080
      nodePort: 30001
  selector:
    app: myweb