K8s的环境变量

k8s-pod注入环境变量

变量值几种定义方式：

• 自定义变量值
• 变量值从Pod属性获取
• 变量值从Secret、ConfigMap获取

参考yaml文件

---
apiVersion: v1
kind: Pod
metadata:
  name: pod-envars
spec:
  containers:
    - name: test
      image: busybox
      command: [ "sh", "-c", "sleep 36000"]
      env:
        - name: MY_NODE_NAME
          valueFrom:
            fieldRef:
              fieldPath: spec.nodeName
        - name: MY_POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        - name: MY_POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: MY_POD_IP
          valueFrom:
            fieldRef:
              fieldPath: status.podIP
        - name: ABC
          value: "123456"   # 自定义变量，后面要加 ""

案例

• 编写一个pod-var.yaml配置文件

  $ vim pod-var.yaml 
  $ cat pod-var.yaml 
  apiVersion: v1
  kind: Pod
  metadata:
    name: pod-envars
  spec:
    containers:
      - name: test
        image: busybox
        command: [ "sh", "-c", "sleep 36000"]
        env:
          - name: MY_NODE_NAME
            valueFrom:
              fieldRef:
                fieldPath: spec.nodeName
          - name: MY_POD_NAME
            valueFrom:
              fieldRef:
                fieldPath: metadata.name
          - name: MY_POD_NAMESPACE
            valueFrom:
              fieldRef:
                fieldPath: metadata.namespace
          - name: MY_POD_IP
            valueFrom:
              fieldRef:
                fieldPath: status.podIP
          - name: ABC
            value: "123456"   # 自定义变量，后面要加 ""
  

• 我们可以通过kubectl describe 查看一个pod或其他的详细信息

  $  kubectl  get pods
  NAME         READY   STATUS    RESTARTS   AGE
  probe-demo   1/1     Running   0          123m
                
  $ kubectl describe pods probe-demo 
  Name:         probe-demo
  Namespace:    default
  Priority:     0
  Node:         k8s-node1/192.168.0.202
  Start Time:   Sun, 29 Nov 2020 14:44:23 +0800
  Labels:       test=liveness
  Annotations:  cni.projectcalico.org/podIP: 10.244.36.90/32
                cni.projectcalico.org/podIPs: 10.244.36.90/32
  Status:       Running
  IP:           10.244.36.90
  IPs:
    IP:  10.244.36.90
  Containers:
    web:
      Container ID:   docker://7e79b87e08f9df2097ac0d2363347dd00eb2e40636c22e0d176f670cc1937548
      Image:          nginx
      Image ID:       docker-pullable://nginx@sha256:6b1daa9462046581ac15be20277a7c75476283f969cb3a61c8725ec38d3b01c3
      Port:           80/TCP
      Host Port:      0/TCP
      State:          Running
        Started:      Sun, 29 Nov 2020 14:44:31 +0800
      Ready:          True
      Restart Count:  0
      Liveness:       tcp-socket :80 delay=0s timeout=1s period=10s #success=1 #failure=3
      Readiness:      tcp-socket :80 delay=30s timeout=1s period=10s #success=1 #failure=3
      Startup:        tcp-socket :80 delay=0s timeout=1s period=10s #success=1 #failure=3
      Environment:    <none>
      Mounts:
        /var/run/secrets/kubernetes.io/serviceaccount from default-token-8pppk (ro)
  Conditions:
    Type              Status
    Initialized       True 
    Ready             True 
    ContainersReady   True 
    PodScheduled      True 
  Volumes:
    default-token-8pppk:
      Type:        Secret (a volume populated by a Secret)
      SecretName:  default-token-8pppk
      Optional:    false
  QoS Class:       BestEffort
  Node-Selectors:  <none>
  Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                   node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
  Events:          <none>
  

• 启动服务

  $ kubectl apply -f pod-var.yaml 
  pod/pod-envars created
  

• 进入容器看看，变量是否可以使用

  $ kubectl exec -it  pod-envars  -- /bin/sh
  / # echo $MY_NODE_NAME
  k8s-node1
  / # echo $MY_POD_NAME
  pod-envars
  / # echo $MY_POD_IP
  10.244.36.91
  

部署一个mysql

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
        - name: mysql
          image: 10.0.0.9:4000/mymysql:5.7.39
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 3306
          #这里引用就是自定义环境变量
          env:
            - name: MYSQL_DATABASE
              value: "wp"
            - name: MYSQL_USER
              value: "wp"
            - name: MYSQL_PASSWORD
              value: "111111"
            - name: MYSQL_ROOT_PASSWORD
              value: "111111"
          volumeMounts:
            - name: mysql-db
              mountPath: /var/lib/mysql
      volumes:
        - name: mysql-db
          persistentVolumeClaim:
            claimName: mysql-pvc

总结

在使用k8s 配置文件传入变量的时候，需要注意在变量上，整数或者字符串需要使用 单引号或双引号，否则或报错