k8s学习笔记之二：Pod

一、deployment部署pod

备注：// 部署pod到指定节点

在启动Pod的yaml文件中与containers同级别的位置添加如下两行即可

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: docker.io/nginx
        ports:
        - containerPort: 80
        resources:
          limits:
             cpu: 100m
          requests:
             cpu: 100m　

2、centos的deployment

kind: Deployment
metadata:
  name: qperf-server
  labels:
    app: qperf-server
spec:
  replicas: 1
  selector:
    matchLabels:
      app: qperf-server
  template:
    metadata:
      labels:
        app: qperf-server
    spec:
      nodeName: node02
      containers:
      - name: centos
        image: centos:latest
        command: ["/bin/sh","-c","while true;do sleep 1;done"]

二、用pod创建一个简单的pod

Ⅰ、创建一个nginx 的pod

apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
  labels:
    app: nginx
spec:
  containers:
  - name: nginx-container
    image: nginx
    ports:
    - containerPort: 80

Ⅱ、创建一个busybox的pod

apiVersion: v1
kind: Pod
metadata:
  name: busybox
  labels:
    app: busybox
spec:
  containers:
  - name: busybox
    image: busybox
    command: ['sh', '-c', 'echo The app is running! && sleep 3600']

三、kubectl常用命令

Ⅰ、不进入容器执行命令

kubectl exec -it podName  -c  containerName -n namespace -- shell comand
例：[root@k8s-master ~]# kubectl exec -it mypod-nginx -c nginx  -- mkdir -p /usr/local/wuchang

Ⅱ、查看阿皮、版本

kubectl api-versions

四、扩容和缩容

1、扩容：通过执行扩容命令，对某个deployment直接进行扩容

kubectl  scale deployment nginx-deployment --replicas=4

2、缩容：当要缩容，减少副本数量即可

kubectl  scale deployment nginx-deployment --replicas=2

3、pod的重启

Deployment 对象并不是直接操控的 Pod 对象，而是操控的 ReplicaSet 对象，而 ReplicaSet 对象就是由副本的数目的定义和Pod 模板组成的。

所以这条命令分别是将ReplicaSet 的数量 scale 到 0，然后又 scale 到 1

kubectl scale deployment esb-admin --replicas=0 -n {namespace}
kubectl scale deployment esb-admin --replicas=1 -n {namespace}

4、查看pod的日志

1、pod若处于运行状态，则通过kubectl logs 即可

[root@node-1 ~]# kubectl logs pod_name -c container_name -n Name_Space
kubectl logs -f <pod_name>

2、若pod处于init状态，则需要通过docker ps查看

通过docker ps 获取该pod的中的CONTAINER ID
[root@node-1 ~]# docker ps | grep pod_name
[root@node-1 ~]# docker logs CONTAINER_ID

五、镜像的更新升级和回滚

1、set images更新

set images：kubectl set image deploy nginxdeploy *=docker.io/jwilder/nginx-proxy

2、patch更新

kubectl patch deployment image-deployment --patch '{"spec": {"template": {"spec": {"containers": [{"name": "nginx","image":"registry.cn-beijing.aliyuncs.com/mrvolleyball/nginx:v1"}]}}}}'

3、回滚

kubectl rollout history deployment web          查看可以回滚的版本
kubectl rollout undo  deployment web    回滚到上一版本

六、postStart和preStop

postStart：容器创建成功后，运行前的任务

apiVersion: v1
kind: Pod
metadata:
  name: lifecycle-demo
spec:
  containers:
  - name: lifecycle-demo-container
    image: nginx
    lifecycle:
      postStart:
         exec:
          command: ["/bin/sh", "-c", "echo Hello from the postStart handler > /usr/share/message"]

preStop：容器被中止前执行

preStop：pod销毁前执行
            preStop:
                 exec:
                    command: ["/usr/sbin/nginx","-s","quit"]

七、探针

1、readinessProbe(就绪检测)：判断返回结果是否符合预期

readinessProbe:
       httpGet:      
          port: 80
       path: /index1.html         //如果存在就能就绪，不存在则无法就绪
initialDelaySeconds: 2  #容器启动后2S开始探测
periodSeconds: 5  #每次探测的间隔时间5S，单位为秒

2、livenessProbe：判断退出状态码是否是0

apiVersion: v1
kind: Pod
metadata:
    name: liveness-exec-pod
spec:
containers:
    - name: liveness-exec-pod
      image: busybox:latest
      imagePullPolicy: IfNotPresent
      command: ["/bin/sh","-c","touch /tmp/healthy;sleep 30;rm -rf /tmp/healthy;sleep 3600"]
      livenessProbe:
               exec:      
                 command: ["test","-e","/tmp/healthy"]     //检测是否存在，存在返回0
      initialDelaySeconds: 2  #容器启动后2S开始探测
      periodSeconds: 5  #每次探测的间隔时间5S，单位为秒