kubernetes云平台管理实战： 最小的资源pod（二）

一、pod初体验

1、编辑k8s_pod.yml文件

[root@k8s-master ~]# cat k8s_pod.yml
apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    app: web
spec:
  containers:
    - name: nginx
      image: 10.0.128.0:5000/nginx:latest
      ports:
        - containerPort: 80

2、下载镜像并上传到私有仓库

[root@k8s-master ~]# docker pull nginx:latest
Trying to pull repository docker.io/library/nginx ...
latest: Pulling from docker.io/library/nginx
177e7ef0df69: Pull complete
ea57c53235df: Pull complete
bbdb1fbd4a86: Pull complete
Digest: sha256:b543f6d0983fbc25b9874e22f4fe257a567111da96fd1d8f1b44315f1236398c
[root@k8s-master ~]# docker tag nginx:latest  10.0.128.0:5000/nginx:latest
[root@k8s-master ~]# docker push 10.0.128.0:5000/nginx:latest
The push refers to a repository [10.0.128.0:5000/nginx]
b7efe781401d: Pushed
c9c2a3696080: Pushed
7b4e562e58dc: Pushed
latest: digest: sha256:e2847e35d4e0e2d459a7696538cbfea42ea2d3b8a1ee8329ba7e68694950afd3 size: 948

3、启动pod

[root@k8s-master ~]# kubectl create -f k8s_pod.yml
pod "nginx" created
[root@k8s-master ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                         PORTS                    NAMES
e166a705c0a7        busybox             "/bin/sh"                31 minutes ago      Exited (0) 10 minutes ago                               cranky_bardeen
ba8d9b958c7c        registry            "/entrypoint.sh /etc/"   44 minutes ago      Up 44 minutes                  0.0.0.0:5000->5000/tcp   registry
15340ee09614        busybox             "/bin/sh"                4 hours ago         Exited (1) About an hour ago                            sleepy_mccarthy

二、无法创建pod故障现象

1、查看pod状态

[root@k8s-master ~]# kubectl get pod
NAME      READY     STATUS              RESTARTS   AGE
nginx     0/1       ContainerCreating   0          2m

2、获取pod详细信息(拍错常用命令)

[root@k8s-master ~]# kubectl describe pod nginx
Name:		nginx
Namespace:	default
Node:		k8s-node1/10.0.128.1
Start Time:	Sun, 20 Jan 2019 13:04:51 +0800
Labels:		app=web
Status:		Pending
IP:
Controllers:	<none>
Containers:
  nginx:
    Container ID:
    Image:			10.0.128.0:5000/nginx:latest
    Image ID:
    Port:			80/TCP
    State:			Waiting
      Reason:			ContainerCreating
    Ready:			False
    Restart Count:		0
    Volume Mounts:		<none>
    Environment Variables:	<none>
Conditions:
  Type		Status
  Initialized 	True
  Ready 	False
  PodScheduled 	True
No volumes.
QoS Class:	BestEffort
Tolerations:	<none>
Events:
  FirstSeen	LastSeen	Count	From			SubObjectPath	Type		Reason		Message
  ---------	--------	-----	----			-------------	--------	------		-------
  3m		3m		1	{default-scheduler }			Normal		Scheduled	Successfully assigned nginx to k8s-node1
  3m		46s		5	{kubelet k8s-node1}			Warning		FailedSync	Error syncing pod, skipping: failed to "StartContainer" for "POD" with ErrImagePull:
  "image pull failed for registry.access.redhat.com/rhel7/pod-infrastructure:latest, this may be because there are no credentials on this request.
  details: (open /etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt: no such file or directory)"

  3m	8s	12	{kubelet k8s-node1}		Warning	FailedSync	Error syncing pod, skipping: failed to "StartContainer" for "POD" with ImagePullBackOff: "Back-off pulling image \"registry.access.redhat.com/rhel7/pod-infrastructure:latest\""

错误是无法从registry.access.redhat.com仓库获取镜像，解决办法是更换镜像地址

三、pod故障解决方案

1、搜索pod-infrastructure

[root@k8s-master ~]# docker search pod-infrastructure

2、下载并上传到私有仓库

[root@k8s-master ~]# docker pull tianyebj/pod-infrastructure
Using default tag: latest
Trying to pull repository docker.io/tianyebj/pod-infrastructure ...
latest: Pulling from docker.io/tianyebj/pod-infrastructure
7bd78273b666: Pull complete
c196631bd9ac: Pull complete
3c917e6a9e1a: Pull complete
Digest: sha256:73cc48728e707b74f99d17b4e802d836e22d373aee901fdcaa781b056cdabf5c
[root@k8s-master ~]# docker images
REPOSITORY                              TAG                 IMAGE ID            CREATED             SIZE
docker.io/registry                      latest              33fbbf4a24e5        2 weeks ago         24.17 MB
10.0.128.0:5000/busybox                 latest              3a093384ac30        2 weeks ago         1.199 MB
docker.io/busybox                       latest              3a093384ac30        2 weeks ago         1.199 MB
10.0.128.0:5000/nginx                   latest              7042885a156a        3 weeks ago         109.2 MB
docker.io/nginx                         latest              7042885a156a        3 weeks ago         109.2 MB
docker.io/tianyebj/pod-infrastructure   latest              34d3450d733b        24 months ago       205 MB
[root@k8s-master ~]# docker tag docker.io/tianyebj/pod-infrastructure:latest 10.0.128.0:5000/pod-infrastructure:latest
[root@k8s-master ~]# docker push 10.0.128.0:5000/pod-infrastructure:latest
The push refers to a repository [10.0.128.0:5000/pod-infrastructure]
ba3d4cbbb261: Pushed
0a081b45cb84: Pushed
df9d2808b9a9: Pushed
latest: digest: sha256:a378b2d7a92231ffb07fdd9dbd2a52c3c439f19c8d675a0d8d9ab74950b15a1b size: 948

3、修改镜像的地址

vim /etc/kubernetes/kubelet
修改内容如下：
KUBELET_POD_INFRA_CONTAINER="--pod-infra-container-image=10.0.128.0:5000/pod-infrastructure:latest"

4、再次查看pod详细信息

[root@k8s-master ~]# kubectl describe pod nginx
Name:		nginx
Namespace:	default
Node:		k8s-node1/10.0.128.1
Start Time:	Sun, 20 Jan 2019 13:04:51 +0800
Labels:		app=web
Status:		Running
IP:		172.16.10.2
Controllers:	<none>
Containers:
  nginx:
    Container ID:		docker://27d25a2ee0248b103991a27b81e3f244382ebdb642694e2aeb5503c373fdb912
    Image:			10.0.128.0:5000/nginx:latest
    Image ID:			docker-pullable://10.0.128.0:5000/nginx@sha256:e2847e35d4e0e2d459a7696538cbfea42ea2d3b8a1ee8329ba7e68694950afd3
    Port:			80/TCP
    State:			Running
      Started:			Sun, 20 Jan 2019 13:48:30 +0800
    Ready:			True
    Restart Count:		0
    Volume Mounts:		<none>
    Environment Variables:	<none>
Conditions:
  Type		Status
  Initialized 	True
  Ready 	True
  PodScheduled 	True
No volumes.
QoS Class:	BestEffort
Tolerations:	<none>
Events:
  FirstSeen	LastSeen	Count	From			SubObjectPath	Type		Reason		Message
  ---------	--------	-----	----			-------------	--------	------		-------
  48m		48m		1	{default-scheduler }			Normal		Scheduled	Successfully assigned nginx to k8s-node1
  48m		6m		13	{kubelet k8s-node1}			Warning		FailedSync	Error syncing pod, skipping: failed to "StartContainer" for "POD" with ErrImagePull: "image pull failed for registry.access.redhat.com/rhel7/pod-infrastructure:latest, this may be because there are no credentials on this request.  details: (open /etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt: no such file or directory)"

  47m	5m	182	{kubelet k8s-node1}		Warning	FailedSync	Error syncing pod, skipping: failed to "StartContainer" for "POD" with ImagePullBackOff: "Back-off pulling image \"registry.access.redhat.com/rhel7/pod-infrastructure:latest\""

  4m	4m	1	{kubelet k8s-node1}	spec.containers{nginx}	Normal	Pulling			pulling image "10.0.128.0:5000/nginx:latest"
  4m	4m	2	{kubelet k8s-node1}				Warning	MissingClusterDNS	kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to DNSDefault policy.
  4m	4m	1	{kubelet k8s-node1}	spec.containers{nginx}	Normal	Pulled			Successfully pulled image "10.0.128.0:5000/nginx:latest"
  4m	4m	1	{kubelet k8s-node1}	spec.containers{nginx}	Normal	Created			Created container with docker id 27d25a2ee024; Security:[seccomp=unconfined]
  4m	4m	1	

[root@k8s-master ~]# kubectl get pod -o wide
NAME      READY     STATUS    RESTARTS   AGE       IP            NODE
nginx     1/1       Running   0          48m       172.16.10.2   k8s-node1

[root@k8s-master ~]# curl 172.16.10.2
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>
elet k8s-node1}	spec.containers{nginx}	Normal	Started			Started container with docker id 27d25a2ee024