pod

由于不能将多个进程聚集在一个单独的容器里，pod应运而生
但是一般pod上还是只跑一个应用除非这些应用
需要一起运行，代表一个整体，一起进行扩缩容

pod共享网络和命名空间，文件系统每个容器是隔离的

yaml文件格式

cat secret_pod.yml 
apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
  - name: mypod
    image: redis
    volumeMounts:
    - name: foo
      mountPath: "/etc/foo"
      readOnly: true
  volumes:
  - name: foo
    secret:
      secretName: mysecret

metadata： 包括名称、命名空间、标签和关于该容器的其他信息
spec：包含pod内容的实际说明，例如pod的容器、卷和其他数据

label 可以使用标签调度pod到对应的节点

验证一下一个pod下不能占用同一个端口

apiVersion: v1
kind: Pod
metadata:
  name: test-pod
  labels:
    name: test-pod
spec:
  containers:
    - name: test-pod1
      image: nginx
      ports:
      - containerPort: 80
    - name: test-pod2
      image: nginx
      ports:
      - containerPort: 80

[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
busybox1 4/4 Running 0 29d
my-nginx-75897978cd-p6p79 1/1 Running 0 39m
my-nginx-75897978cd-z67ch 1/1 Running 0 39m
mypod 1/1 Running 0 36d
test-pod 1/2 CrashLoopBackOff 2 73s

验证一下pod共享存储

**cat pod-volume-applogs.yaml** 
apiVersion: v1
kind: Pod
metadata:
  name: volume-pod
spec:
  containers:
  - name: tomcat
    image: tomcat
    ports:
    - containerPort: 8080
    volumeMounts:
    - name: app-logs
      mountPath: /usr/local/tomcat/logs
  - name: logreader
    image: busybox
    command: ['sh','-c','tail -f /logs/catalina*.log']
    volumeMounts:
    - name: app-logs
      mountPath: /logs
  volumes:
  - name: app-logs
    emptyDir: {
     }

tomcat把日志写到app-logs里面，busybox读日志
能在busybox里面看到tomcat的启动日志