kubernetes集群系列资料06--pod介绍

一、pod介绍

二、pod全生命周期

三、pod案例

##########K8S案例1---pod#############
#####init容器使用案例---视频19有讲解。
vim myapp.yaml  #包含init C的POD模板，该initC会解析2个域名。
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
apiVersion: v1          #内容格式为group/apiversion,如果没有给定group名称则默认为core；
kind: Pod               #资源类别；
metadata:               #资源元数据；
    name: myapp-pod
    labels:
        app: myapp
    # annotations：      #主要目的是方便用户阅读查找。
spec:                   #期望的状态；
    containers:
    - name: myapp-container     #mainC容器，主要目的时输出“The app is running”，然后等待3600s；
      image: busybox            #mainC容器的使用镜像busybox:是一个封装很多小工具的镜像。
      command: ['sh','-c','echo The app is running! && sleep 3600'] #mainC容器中的执行命令。
    initContainers:             #为myapp-container创建初始化容器。
    - name: init-myservice
      image: busybox
      command: ['sh','-c','until nslookup myservice;do echo waiting for myservice;sleep 2;done;']  #运行命令：解析myservice直至其成功为止。
    - name: init-mydb
      image: busybox
      command: ['sh','-c','until nslookup mydb;do echo waiting for mydb;sleep 2;done;']
# status：             #当前状态，本字段有k8s自身维护，用户不能去定义；
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kubectl apply -f myapp.yaml
kubectl get pod                 #myapp-pod状态为Init:0/2；其故障原因：解析myservice、mydb不成功，导致执行initC一直在重启而不能进入下一步；
kubectl logs myapp-pod          #查看myapp-pod的日志；
kubectl describe pod myapp-pod  #查看myapp-pod的详细信息，定位错误点；
kubectl edit pod myapp-pod      #修改pod的内容；该yaml文件有些内容时不可更改，有些内容更改了也不能触发initC的重新执行，但可通过修改image字段会触发initC的重新执行。
kubectl logs myapp-pod -c init-myservice  #查看pod下定义的init-myservice服务的日志。


# ##在node节点上传busybox至harbor
# docker tag busybox:latest hub.atguigu.com/library/busybox:latest
# docker push hub.atguigu.com/library/busybox

vim myservice.yaml  #将myservice域名写入coreDNS服务器的POD;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
apiVersion: v1
kind: Service
metadata:
    name: myservice
spec:
    ports:
    - protocol: TCP
      port: 80
      targetPort: 9376
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kubectl apply -f myservice.yaml
ubectl get svc          #查看创建的服务；
kubectl get pod -w      #一直监测pod的执行过程；


vim mydb.yaml  #将mydb域名写入coreDNS服务器的POD;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
apiVersion: v1
kind: Service
metadata:
    name: mydb
spec:
    ports:
    - protocol: TCP
      port: 80
      targetPort: 9377
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kubectl apply -f mydb.yaml



####检测探针---就绪检测
docker pull mylandmarktech/myapp
docker tag mylandmarktech/myapp hub.atguigu.com/library/mylandmarktech/myapp:v1


vim readinessProbe-httpget.yaml  #通过确认容器是否能访问index1.html来判断容器nginx是否就绪。
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
apiVersion: v1
kind: Pod
metadata:
    name: readiness-httpget-pod
    namespace: default
spec:
    containers:
    - name: readiness-httpget-container
      image: hub.atguigu.com/library/nginx
      imagePullPolicy: IfNotPresent   #若本地存在image则不需下载；
      readinessProbe:
        httpGet:
            port: 80
            path: /index1.html
        initialDelaySeconds: 1
        periodSeconds: 3
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kubectl apply -f readinessProbe-httpget.yaml
kubectl exec -it readiness-httpget-pod -- /bin/sh   #进入pod的单一容器内部，进入交互式操作。
kubectl exec -it readiness-httpget-pod  -c k8s_readiness-httpget-container_readiness-httpget-pod_default_0c0c5c17-895c-4353-8930-fe4730aecaa7_0 -- /bin/sh  #若pod中只有一个容器则可不需使用“-c ”参数指定容器。
kubectl exec -it readiness-httpget-pod ls /usr/share/nginx/html  #无参数可省略--。
kubectl exec -it readiness-httpget-pod -- ls -l /usr/share/nginx/html  #要加-- 号，不然shell命令中的参数，不能识别;
kubectl exec -it readiness-httpget-pod -- echo "123" >/usr/share/nginx/html/index1.html  #无法实现直接创建文件？？？



####检测探针---存活检测
vim livenessProbe-exec.yaml  #容器不断创建文件后删除，通过检测该文件是否存在来确认容器为正常存活状态，若不存在则重新创建pod；
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
apiVersion: v1
kind: Pod
metadata:
    name: liveness-exec-pod
    namespace: default
spec:
    containers:
    - name: liveness-exec-container
      image: hub.atguigu.com/library/busybox
      imagePullPolicy: IfNotPresent
      command: ["/bin/sh","-c","touch /tmp/live;sleep 60;rm -rf /tmp/live;sleep 3600"]
      livenessProbe:
        exec:
            command: ["test","-e","/tmp/live"]
        initialDelaySeconds: 1
        periodSeconds: 3
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kubectl apply -f livenessProbe-exec.yaml
kubectl exec -it liveness-exec-pod -- ls -l /tmp/live  #查看文件是否存活来判断pod是否正常运行；
kubectl get pod -w #监控pod是否被反复重启，若pod退出会自动重启。

vim livenessProbe-httpget.yaml  #
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
apiVersion: v1
kind: Pod
metadata:
    name: liveness-httpget-pod
    namespace: default
spec:
    containers:
    - name: liveness-httpget-container
      image: hub.atguigu.com/library/nginx
      imagePullPolicy: IfNotPresent
      ports:
      - name: http
        containerPort: 80
      livenessProbe:
        httpGet:
            port: http
            path: /index.html
        initialDelaySeconds: 1
        periodSeconds: 3
        timeoutSeconds: 10
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kubectl apply -f livenessProbe-httpget.yaml
kubectl exec -it liveness-httpget-pod -- rm -f /usr/share/nginx/html/index.html  #查看文件是否存活来判断pod是否正常运行；
kubectl get pod -w #监控pod是否被重启1次，若pod退出会自动重启。





vim livenessProbe-tcp.yaml
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
apiVersion: v1
kind: Pod
metadata:
    name: liveness-tcp-pod
    namespace: default
spec:
    containers:
    - name: liveness-tcp-container
      image: hub.atguigu.com/library/nginx
      imagePullPolicy: IfNotPresent
      livenessProbe:
        tcpSocket:
            port: 80
        initialDelaySeconds: 5  #等5秒后开始存活检测；
        periodSeconds: 3        #未成功检测再过3秒后检测；
        timeoutSeconds: 1       #存活检测超时时间为1s，若仍不能检测到端口，则重启POD；
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kubectl apply -f livenessProbe-tcp.yaml
docker stop k8s_liveness-tcp-container_liveness-tcp-pod_default_4794b8bf-4ddb-4e0b-b07b-cec04dfa99f0_0;docker ps -a #在工作节点停止容器后进行查看容器是否被重启；
kubectl get pod -w #监控pod是否被重启1次。

####启动、退出动作

vim start-stop.yaml
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
apiVersion: v1
kind: Pod
metadata:
    name: lifecycle-demo
    namespace: default
spec:
    containers:
    - name: lifecycle-demo-container
      image: hub.atguigu.com/library/nginx:latest
      lifecycle:
        postStart:
            exec:
                command: ["/bin/sh","-c","echo Hello from the postStart handler > /usr/share/message"]
        preStop:
            exec:
                command: ["/bin/sh","-c","echo Hello from the poststop handler > /usr/share/message"]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kubectl apply -f start-stop.yaml
kubectl exec -it lifecycle-demo -- exit && cat /usr/share/message #查看容器启动成功后输出的日志信息。

##########K8S案例1---pod#############