Kubernetes基础：包含多个容器的Pod_查看pod应该起几个容器

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]# 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

生成Pod

[root@host131 Pod]# kubectl create -f multi-pods.yaml 
pod/multi-pods created
[root@host131 Pod]# 
1
2
3

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]# 
1
2
3
4

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]#
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93

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
/ # 
1
2
3
4
5
6
7
8
9
10
11
12
13
14

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]# 
1
2
3
4
5
6

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]# 
1
2
3

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]# 
1
2
3
4
5
6
7
8
9
10
11
12
13
14

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.
/ # 
1
2
3
4