Kubernetes中的Pod使用案例

Pod是Kubernetes中的一个最小单位，Pod中的容器共享存储、网络、以及怎样运行这些容器的声明。

容器相关

.spec.containers 该项是数组，表示可以有多个容器

以单个容器为例

---

.spec.containers[0].name 配置容器名字

.spec.containers[0].name 配置容器使用的镜像

apiVersion: v1
kind: Pod
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  containers:
    - image: nginx
      name: ngin

.spec.containers[0].resources 配置容器资源限额

apiVersion: v1
kind: Pod
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  containers:
    - image: nginx
      name: nginx
      resources:
        requests: # 需求资源
          cpu: "300m"
          memory: "64Mi"
        limits:  # 最大资源
          cpu: "500m"
          memory: "128Mi"

CPU的单位是milicpu，500mcpu=0.5cpu；而内存的单位则包括E, P, T, G, M, K, Ei, Pi, Ti, Gi, Mi, Ki等。

.spec.containers[0].livenessProbe 探测容器是否健康

apiVersion: v1
kind: Pod
metadata:
  labels:
    app: nginx
  name: nginx
spec:
    containers:
    - image: nginx
      imagePullPolicy: Always
      name: http
      livenessProbe:
        httpGet:
        path: /
        port: 80
        initialDelaySeconds: 15
        timeoutSeconds: 1

.spec.containers[0].readinessProbe 探测容器是否是正常服务状态

apiVersion: v1
kind: Pod
metadata:
  labels:
    app: nginx
  name: nginx
spec:
    containers:
    - image: nginx
      imagePullPolicy: Always
      name: http
      readinessProbe:
        httpGet:
        path: /ping
        port: 80
        initialDelaySeconds: 5
        timeoutSeconds: 1

.spec.containers[0].lifecycle 容器生命周期钩子

spec:
  containers:
  - name: lifecycle-demo-container
    image: nginx
    lifecycle:
      postStart: # 容器启动后
        exec:
          command: ["/bin/sh", "-c", "echo Hello from the postStart handler > /usr/share/message"]
      preStop:   # 容器销毁前
        exec:
          command: ["/usr/sbin/nginx","-s","quit"]

.spec.containers[0].env设置容器环境变量

apiVersion: v1
kind: Pod
metadata:
  name: dapi-envars-fieldref
spec:
  containers:
    - name: test-container
      image: k8s.gcr.io/busybox
      command: [ "sh", "-c"]
      args:
      - while true; do
          echo -en '\n';
          printenv MY_NODE_NAME MY_POD_NAME MY_POD_NAMESPACE;
          printenv MY_POD_IP MY_POD_SERVICE_ACCOUNT;
          sleep 10;
        done;
      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: MY_POD_SERVICE_ACCOUNT
          valueFrom:
            fieldRef:
              fieldPath: spec.serviceAccountName

---

Pod相关

.spec.initContainers Init Container在所有容器运行之前执行

apiVersion: v1
kind: Pod
metadata:
  name: init-demo
spec:
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 80
    volumeMounts:
    - name: workdir
      mountPath: /usr/share/nginx/html
  initContainers:
  - name: install
    image: busybox
    command:
    - wget
    - "-O"
    - "/work-dir/index.html"
    - http://kubernetes.io
    volumeMounts:
    - name: workdir
      mountPath: "/work-dir"
  dnsPolicy: Default
  volumes:
  - name: workdir
    emptyDir: {}

常用来初始化配置

.spec.imagePullSecrets 使用私有镜像

apiVersion: v1
kind: Pod
metadata:
  name: private-reg
spec:
  containers:
    - name: private-reg-container
      image: <your-private-image>
  imagePullSecrets:
    - name: regsecret

.spec.volumes Volume可以为容器提供持久化存储

apiVersion: v1
kind: Pod
metadata:
  name: redis
spec:
  containers:
  - name: redis
    image: redis
    volumeMounts:
    - name: redis-storage
      mountPath: /data/redis
  volumes:
  - name: redis-storage
    emptyDir: {}

.spec.restartPolicy 设置镜像拉取规则

• Always：不管镜像是否存在都会进行一次拉取。
• Never：不管镜像是否存在都不会进行拉取
• IfNotPresent：只有镜像不存在时，才会进行镜像拉取。

apiVersion: v1
kind: Pod
metadata:
  name: dapi-envars-fieldref
spec:
  containers:
    - name: test-container
      image: k8s.gcr.io/busybox
  restartPolicy: Never

.spec.nodeSelector 指定node

apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    env: test
spec:
  containers:
  - name: nginx
    image: nginx
  nodeSelector:
    disktype: ssd