一、pod简介
Pod是可以创建和管理Kubernetes计算的最小可部署单元，一个Pod代表着集群
中运行的一个进程，每个pod都有一个唯一的ip。
一个pod类似一个豌豆荚，包含一个或多个容器（通常是docker），多个容器间
共享IPC、Network和UTC namespace
二、pod管理

kubectl命令：https://kubernetes.io/docs/reference/generated/kubectl/kubectl- commands

harbor仓库中导入后续实验所需的镜像，可以直接在阿里云镜像官网下载

https://developer.aliyun.com/mirror/

2.1创建自主式pod

当前节点状态
[root@server2 ~]# kubectl get node
NAME      STATUS   ROLES    AGE     VERSION
server2   Ready    master   41h     v1.18.4
server3   Ready    <none>   3m32s   v1.18.4
server4   Ready    <none>   40h     v1.18.4

创建pod；run：指定名称Nginx也可以是其他名称，--image：指定镜像
[root@server2 ~]# kubectl run nginx --image=nginx  
pod/nginx created
[root@server2 ~]# kubectl get pod  查看运行的pod；正常运行
NAME    READY   STATUS    RESTARTS   AGE
nginx   1/1     Running   0          6s
[root@server2 ~]# kubectl get pod -o wide  查看pod：IP和运行主机
NAME    READY   STATUS    RESTARTS   AGE   IP           NODE      NOMINATED NODE   READINESS GATES
nginx   1/1     Running   0          19s   10.244.2.2   server4   <none>           <none>
[root@server2 ~]# kubectl describe pod nginx  查看pod的详细信息

只要是在集群当中都可以访问，集群外部无法访问

在server4节点上查看

删除pod
[root@server2 ~]# kubectl delete pod nginx
pod "nginx" deleted
[root@server2 ~]# kubectl get pod 
No resources found in default namespace.

2.2使用控制器来创建pod

[root@server2 ~]# kubectl create deployment  myapp --image=nginx  创建pod
deployment.apps/myapp created
[root@server2 ~]# kubectl get pod  查看
NAME                     READY   STATUS    RESTARTS   AGE
myapp-687598b8b4-ldxpk   1/1     Running   0          8s
myapp:控制器名称 ；687598b8b4 ：（replicaset）简称：rs  ；ldxpk:容器名称默认只要一个可以做拉伸

[root@server2 ~]# kubectl delete pod myapp-687598b8b4-ldxpk  删除pod之后
pod "myapp-687598b8b4-ldxpk" deleted
[root@server2 ~]# kubectl get pod  再次可查看，自动拉取一个副本
NAME                     READY   STATUS    RESTARTS   AGE
myapp-687598b8b4-p5wcs   1/1     Running   0          15s
完全彻底删除：直接删掉控制器
[root@server2 ~]# kubectl delete deployments.apps myapp  删除控制器
deployment.apps "myapp" deleted
[root@server2 ~]# kubectl get pod  查看
NAME                     READY   STATUS        RESTARTS   AGE
myapp-687598b8b4-p5wcs   0/1     Terminating正在回收中   0          6m24s
[root@server2 ~]# kubectl get pod  再次查看回首成功
No resources found in default namespace.

2.3pod手动扩容和缩容

[root@server2 ~]# kubectl create deployment  myapp --image=nginx  创建一个控制器pod或自主式
deployment.apps/myapp created
[root@server2 ~]# kubectl get pod  查看
NAME                     READY   STATUS    RESTARTS   AGE
myapp-687598b8b4-bpf59   1/1     Running   0          4s
[root@server2 ~]# kubectl scale deployment myapp --replicas=2  扩容两个
deployment.apps/myapp scaled
[root@server2 ~]# kubectl get pod  查看
NAME                     READY   STATUS    RESTARTS   AGE
myapp-687598b8b4-4z7ns   1/1     Running   0          2s
myapp-687598b8b4-bpf59   1/1     Running   0          78s
[root@server2 ~]# kubectl scale deployment myapp --replicas=5  扩容五个
deployment.apps/myapp scaled
[root@server2 ~]# kubectl get pod
NAME                     READY   STATUS    RESTARTS   AGE
myapp-687598b8b4-4slxf   1/1     Running   0          5s
myapp-687598b8b4-bpf59   1/1     Running   0          4m39s
myapp-687598b8b4-crcm7   1/1     Running   0          5s
myapp-687598b8b4-gl9gb   1/1     Running   0          3m15s
myapp-687598b8b4-sxcx7   1/1     Running   0          5s


[root@server2 ~]# kubectl scale deployment myapp --replicas=2  缩容
deployment.apps/myapp scaled
[root@server2 ~]# kubectl get pod  其他的正在回收
NAME                     READY   STATUS        RESTARTS   AGE
myapp-687598b8b4-4q6mw   1/1     Terminating   0          114s
myapp-687598b8b4-4z7ns   1/1     Terminating   0          2m2s
myapp-687598b8b4-bpf59   1/1     Running       0          3m18s
myapp-687598b8b4-gl9gb   1/1     Running       0          114s
myapp-687598b8b4-kgpqw   1/1     Terminating   0          114s
[root@server2 ~]# kubectl get pod  查看
NAME                     READY   STATUS    RESTARTS   AGE
myapp-687598b8b4-bpf59   1/1     Running   0          3m57s
myapp-687598b8b4-gl9gb   1/1     Running   0          2m33s

2.4.service设定
service是一个抽象概念，定义了一个服务的多个pod逻辑合集和访问pod的策略，
一般把service称为微服务；主要是提供负载均衡和服务自动发现。
创建service

此时pod客户端可以通过service的名称访问后端的两个Pod
 kubectl expose deployment nginx --port=80 --target-port=80
ClusterIP: 默认类型，自动分配一个仅集群内部可以访问的虚拟IP；
   仅仅作用于Kubernetes Service这个对象，由Kubernetes自己来进行管理和分配地址；
   当然我们也无法ping这个地址，他没有一个真正的实体对象来响应；
   只能结合Service Port来组成一个可以通信的服务。

[root@server2 ~]# kubectl get pod
NAME                     READY   STATUS    RESTARTS   AGE
myapp-687598b8b4-7j5q5   1/1     Running   0          4s
myapp-687598b8b4-grmbb   1/1     Running   0          8s
[root@server2 ~]# kubectl get deployments.apps   查看deployment名称
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
myapp   2/2     2            2           3m7s

端口映射   指定端口：--port=80   --target-port=80 ：容器监听端口目标端口
[root@server2 ~]# kubectl expose deployment myapp  --port=80 --target-port=80
service/myapp exposed
[root@server2 ~]# kubectl get svc -o wide  查看服务
NAME         TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE   SELECTOR
kubernetes   ClusterIP   10.96.0.1     <none>        443/TCP   42h   <none>
myapp        ClusterIP   10.96.77.38   <none>        80/TCP    29s   app=myapp

[root@server2 ~]# kubectl get pod --show-labels   查看pod的标签通过标签绑定IP
NAME                     READY   STATUS    RESTARTS   AGE   LABELS
myapp-687598b8b4-7j5q5   1/1     Running   0          10m   app=myapp,pod-template-hash=687598b8b4
myapp-687598b8b4-grmbb   1/1     Running   0          10m   app=myapp,pod-template-hash=687598b8b4

2.5pod镜像更新和回滚

[root@server2 ~]# kubectl get pod 
NAME                     READY   STATUS    RESTARTS   AGE
myapp-687598b8b4-7j5q5原始   1/1     Running   0          37m
myapp-687598b8b4-grmbb原始   1/1     Running   0          37m
[root@server2 ~]# kubectl set image deployments myapp nginx=myapp:v1 --record 更新
deployment.apps/myapp image updated

[root@server2 ~]# kubectl get pod 
NAME   rs:也已经更新             READY   STATUS    RESTARTS   AGE
myapp-76df559f68-995gd 已更新    1/1     Running    0          16s
myapp-76df559f68-pr6pr 已更新    1/1     Running     0          19s

查看历史版本
[root@server2 ~]# kubectl rollout history deployment myapp
deployment.apps/myapp 
REVISION  CHANGE-CAUSE
1         <none>
2         kubectl set image deployments myapp nginx=myapp:v1 --record=true

创建一个交互式的shell
[root@server1 ~]# docker search busyboxplus  搜索
[root@server1 ~]# docker pull busyboxplus  下载
打标签并上传harbor仓库

[root@server2 ~]# kubectl get  svc  查看服务信息
NAME         TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1     <none>        443/TCP   44h
myapp        ClusterIP   10.96.77.38   <none>        80/TCP    116m
[root@server2 ~]# kubectl  run demo --image=busyboxplus -it   运行交互式shell
[root@server2 ~]# kubectl  attach demo -it   进入交互式shell
curl 10.96.77.38
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
curl 10.96.77.38/hostname.html  再次测试实现负载均衡

kubectl rollout undo deployment myapp --to-revision=2  回退版本
kubectl set image deployments myapp nginx=myapp:v2  --record=true  更换pod 镜像
kubectl get  rs  查看rs

2.6让外部节点访问pod

此端口随机分配：32195

查看节点端口

[root@server3 ~]# netstat -tnpl | grep 32195
tcp        0      0 0.0.0.0:32195           0.0.0.0:*               LISTEN      70165/kube-proxy    
[root@server4 ~]# netstat -tnpl | grep 32195
tcp        0      0 0.0.0.0:32195           0.0.0.0:*               LISTEN      63968/kube-proxy