Kubernetes基础：包含多个容器的Pod

灰太狼 2023-07-04 08:48 21阅读 0赞

在前面的文章中介绍了Pod的使用方法，示例中的Pod包含一个容器，这篇文章介绍一下包含多个容器的Pod的使用方法。

# YAML文件示例 #

[root@host131 Pod]# cat multi-pods.yaml 
    ---
    apiVersion: v1
    kind: Pod
    metadata:
      name: multi-pods
    spec:
      containers:
      - name: blue-pod-container
        image: busybox:1.31.1
        command: ["sleep"]
        args:    ["1000"]
      - name: green-pod-container
        image: busybox:1.30.1
        command: ["sleep"]
        args:    ["10000"]
      - name: yellow-pod-container
        image: busybox:1.30.1
        command: ["sleep"]
        args:    ["100000"]
    ...
    [root@host131 Pod]#

# 生成Pod #

[root@host131 Pod]# kubectl create -f multi-pods.yaml 
    pod/multi-pods created
    [root@host131 Pod]#

# 确认Pod信息 #

使用kubectl get pods命令可以获取此pod的详细信息，可以看到READY显示为3/3，说明包含三个容器全部正常启动，整体状态STATUS为Running状态，Pod本身的IP为10.254.176.3，Pod名称为multi-pods。

[root@host131 Pod]# kubectl get pods -o wide
    NAME         READY   STATUS    RESTARTS   AGE   IP             NODE              NOMINATED NODE   READINESS GATES
    multi-pods   3/3     Running   0          27s   10.254.176.3   192.168.163.131   <none>           <none>
    [root@host131 Pod]#

然后可以使用kubectl describe查看pod的详细信息：

[root@host131 Pod]# kubectl describe pod/multi-pods
    Name:         multi-pods
    Namespace:    default
    Priority:     0
    Node:         192.168.163.131/192.168.163.131
    Start Time:   Sun, 09 Feb 2020 04:34:18 -0500
    Labels:       <none>
    Annotations:  <none>
    Status:       Running
    IP:           10.254.176.3
    IPs:
      IP:  10.254.176.3
    Containers:
      blue-pod-container:
        Container ID:  docker://881da8a39e6a9999cce25ef227c97e8680379d97cd190e6a98ff25f49a3f7469
        Image:         busybox:1.31.1
        Image ID:      docker-pullable://busybox@sha256:6915be4043561d64e0ab0f8f098dc2ac48e077fe23f488ac24b665166898115a
        Port:          <none>
        Host Port:     <none>
        Command:
          sleep
        Args:
          1000
        State:          Running
          Started:      Sun, 09 Feb 2020 04:34:19 -0500
        Ready:          True
        Restart Count:  0
        Environment:    <none>
        Mounts:
          /var/run/secrets/kubernetes.io/serviceaccount from default-token-kzxwt (ro)
      green-pod-container:
        Container ID:  docker://b60d1cf06ff68ffae44e13f33d84b12b8525707af6de1836abdc5905a135166f
        Image:         busybox:1.30.1
        Image ID:      docker-pullable://busybox@sha256:4b6ad3a68d34da29bf7c8ccb5d355ba8b4babcad1f99798204e7abb43e54ee3d
        Port:          <none>
        Host Port:     <none>
        Command:
          sleep
        Args:
          10000
        State:          Running
          Started:      Sun, 09 Feb 2020 04:34:19 -0500
        Ready:          True
        Restart Count:  0
        Environment:    <none>
        Mounts:
          /var/run/secrets/kubernetes.io/serviceaccount from default-token-kzxwt (ro)
      yellow-pod-container:
        Container ID:  docker://8e500fef966ab861843d46076bdb07fa5443041bcc6b20c2a415ef5aed181cdf
        Image:         busybox:1.30.1
        Image ID:      docker-pullable://busybox@sha256:4b6ad3a68d34da29bf7c8ccb5d355ba8b4babcad1f99798204e7abb43e54ee3d
        Port:          <none>
        Host Port:     <none>
        Command:
          sleep
        Args:
          100000
        State:          Running
          Started:      Sun, 09 Feb 2020 04:34:19 -0500
        Ready:          True
        Restart Count:  0
        Environment:    <none>
        Mounts:
          /var/run/secrets/kubernetes.io/serviceaccount from default-token-kzxwt (ro)
    Conditions:
      Type              Status
      Initialized       True 
      Ready             True 
      ContainersReady   True 
      PodScheduled      True 
    Volumes:
      default-token-kzxwt:
        Type:        Secret (a volume populated by a Secret)
        SecretName:  default-token-kzxwt
        Optional:    false
    QoS Class:       BestEffort
    Node-Selectors:  <none>
    Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                     node.kubernetes.io/unreachable:NoExecute for 300s
    Events:
      Type    Reason     Age    From                      Message
      ----    ------     ----   ----                      -------
      Normal  Scheduled  2m47s  default-scheduler         Successfully assigned default/multi-pods to 192.168.163.131
      Normal  Pulled     2m46s  kubelet, 192.168.163.131  Container image "busybox:1.31.1" already present on machine
      Normal  Created    2m46s  kubelet, 192.168.163.131  Created container blue-pod-container
      Normal  Started    2m46s  kubelet, 192.168.163.131  Started container blue-pod-container
      Normal  Pulled     2m46s  kubelet, 192.168.163.131  Container image "busybox:1.30.1" already present on machine
      Normal  Created    2m46s  kubelet, 192.168.163.131  Created container green-pod-container
      Normal  Started    2m46s  kubelet, 192.168.163.131  Started container green-pod-container
      Normal  Pulled     2m46s  kubelet, 192.168.163.131  Container image "busybox:1.30.1" already present on machine
      Normal  Created    2m46s  kubelet, 192.168.163.131  Created container yellow-pod-container
      Normal  Started    2m46s  kubelet, 192.168.163.131  Started container yellow-pod-container
    [root@host131 Pod]#

可以看到在Containers段显示了三个容器的详细信息，而在Event中也可以看到三个容器的创建过程。

# 进入容器 #

Pod中只有一个容器时，使用如下命令即可进入到容器之中：

> 执行命令：kubectl exec -it pod名称 sh或者bash

而如果有多个容器时，则需要使用-c指定容器名称：

> 执行命令：kubectl exec -it pod名称 -c 容器名称 sh或者bash

比如进入multi-pods中名为yellow-pod-container ：

[root@host131 Pod]# kubectl exec -it multi-pods -c yellow-pod-container sh
    / # ps -ef
    PID   USER     TIME  COMMAND
        1 root      0:00 sleep 100000
        6 root      0:00 sh
       11 root      0:00 ps -ef
    / # busybox |grep BusyBox
    BusyBox v1.30.1 (2019-05-09 01:23:43 UTC) multi-call binary.
    BusyBox is copyrighted by many authors between 1998-2015.
    	BusyBox is a multi-call binary that combines many common Unix
    	link to busybox for each function they wish to use and BusyBox
    / # hostname
    multi-pods
    / #

pause镜像确认，使用docker ps命令可以确认到包含pause在内的4个容器，pause容器作为此Pod的根容器，负责整个Pod的网络信息

[root@host131 Pod]# docker ps |grep multi-pods
    8e500fef966a        64f5d945efcc                               "sleep 100000"           8 minutes ago       Up 8 minutes                            k8s_yellow-pod-container_multi-pods_default_3c744cee-6ce3-4de3-99ab-f8909fee0147_0
    b60d1cf06ff6        64f5d945efcc                               "sleep 10000"            8 minutes ago       Up 8 minutes                            k8s_green-pod-container_multi-pods_default_3c744cee-6ce3-4de3-99ab-f8909fee0147_0
    881da8a39e6a        6d5fcfe5ff17                               "sleep 1000"             8 minutes ago       Up 8 minutes                            k8s_blue-pod-container_multi-pods_default_3c744cee-6ce3-4de3-99ab-f8909fee0147_0
    44d9b05a6d1b        gcr.io/google_containers/pause-amd64:3.1   "/pause"                 8 minutes ago       Up 8 minutes                            k8s_POD_multi-pods_default_3c744cee-6ce3-4de3-99ab-f8909fee0147_0
    [root@host131 Pod]#

首先确认pause的id

[root@host131 Pod]# docker inspect k8s_POD_multi-pods_default_3c744cee-6ce3-4de3-99ab-f8909fee0147_0 |grep Id
           "Id": "44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb",
    [root@host131 Pod]#

然后可以确认到在其余的容器中都和此Pod有所关联,可以看到Pause作为根容器为其余容器所起到的作用。

[root@host131 Pod]# docker inspect k8s_yellow-pod-container_multi-pods_default_3c744cee-6ce3-4de3-99ab-f8909fee0147_0 |grep 44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb
           "ResolvConfPath": "/var/lib/docker/containers/44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb/resolv.conf",
           "HostnamePath": "/var/lib/docker/containers/44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb/hostname",
               "NetworkMode": "container:44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb",
               "IpcMode": "container:44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb",
                   "io.kubernetes.sandbox.id": "44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb"
    [root@host131 Pod]# 
    [root@host131 Pod]# docker inspect k8s_green-pod-container_multi-pods_default_3c744cee-6ce3-4de3-99ab-f8909fee0147_0 |grep 44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb
           "ResolvConfPath": "/var/lib/docker/containers/44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb/resolv.conf",
           "HostnamePath": "/var/lib/docker/containers/44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb/hostname",
               "NetworkMode": "container:44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb",
               "IpcMode": "container:44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb",
                   "io.kubernetes.sandbox.id": "44d9b05a6d1b9f33e170a70a4db304b92e4dbbdd3d0a38efaca0513ad8b86acb"
    [root@host131 Pod]#

另外如果不使用-c指定容器时，缺省会进入第一个容器中

[root@host131 Pod]# kubectl exec -it multi-pods sh
    Defaulting container name to blue-pod-container.
    Use 'kubectl describe pod/multi-pods -n default' to see all of the containers in this pod.
    / #