k8s常用操作

写在前面

本文记录k8s的常见操作毕竟好记性不如烂笔头。

1pod查看日志

dongyunqi@dongyunqi-virtual-machine:~/test$ kubectl logs busy-pod
ubuntu, on

因为pod中只有一个容器所以不需要指定容器当有多个容器时需要指定容器如下:

dongyunqi@dongyunqi-virtual-machine:~/test$ kubectl logs ngx-num1-pod -c ngx1111
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
...

2查看pod信息

可以直接查看也可以通过label过滤查看如下

dongyunqi@mongodaddy:~/k8s$ kubectl get pod
NAME                           READY   STATUS    RESTARTS        AGE
ngx-dep-name-dcc8b7bfd-7lbrq   1/1     Running   0               17m
ngx-dep-name-dcc8b7bfd-9m2rs   1/1     Running   0               17m
ngx-dep-name-dcc8b7bfd-wp4zt   1/1     Running   0               17m
redis-ds-5jf5x                 1/1     Running   1 (4h34m ago)   40h
redis-ds-n8p45                 1/1     Running   1 (4h34m ago)   40h
5可以根据POD的label来过滤POD支持使用==、!=、in、notin等表达式如下
    dongyunqi@mongodaddy:~/k8s$ kubectl get pod -l 'app in (ngx, nginx, ngx-dep-pod)'
    NAME                            READY   STATUS    RESTARTS   AGE
    ngx-dep-name-577dd8d59b-4xkd2   1/1     Running   0          3m34s
    ngx-dep-name-577dd8d59b-dcx8k   1/1     Running   0          3m34s
    ngx-dep-name-577dd8d59b-f2kxp   1/1     Running   0          3m34s
    dongyunqi@mongodaddy:~/k8s$ kubectl get pod -l 'app=ngx-dep-pod'
    NAME                            READY   STATUS    RESTARTS   AGE
    ngx-dep-name-577dd8d59b-4xkd2   1/1     Running   0          3m59s
    ngx-dep-name-577dd8d59b-dcx8k   1/1     Running   0          3m59s
    ngx-dep-name-577dd8d59b-f2kxp   1/1     Running   0          3m59s

3查看pod中运行的容器

3.1describe

dongyunqi@mongodaddy:~/k8s$ kubectl describe pod ngx-dep-name-dcc8b7bfd-7lbrq | grep Events -A 100
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  34m   default-scheduler  Successfully assigned default/ngx-dep-name-dcc8b7bfd-7lbrq to mongomummy # pod分配的Node
  Normal  Pulled     34m   kubelet            Container image "nginx:alpine" already present on machine # 创建容器使用的镜像
  Normal  Created    34m   kubelet            Created container nginx # 创建容器显示的是容器的名称
  Normal  Started    34m   kubelet            Started container nginx
dongyunqi@mongodaddy:~/k8s$ kubectl describe pod ngx-dep-name-dcc8b7bfd-7lbrq | grep Containers: -A 100
Containers: # 所有的容器信息
  nginx: # 容器的名称
    Container ID:   docker://87afa9c8b6c1a9c8434a5dcbe39eb55863ecff4c91a68b408a3fd5f11b18a86f
    Image:          nginx:alpine # 容器使用的镜像
    Image ID:       docker-pullable://nginx@sha256:eb05700fe7baa6890b74278e39b66b2ed1326831f9ec3ed4bdc6361a4ac2f333
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Thu, 12 Jan 2023 14:59:05 +0800
    Ready:          True
    Restart Count:  0 # 容器重启的此时
    Environment:    <none>
    Mounts:
      /etc/nginx/conf.d from ngx-conf-vol (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-wlbhf (ro)

3.2jsonpath过滤

dongyunqi@mongodaddy:~/k8s$ kubectl get pods ngx-dep-name-dcc8b7bfd-7lbrq -o jsonpath={.spec.containers[*].name}
nginx

4通过events排查异常POD

当POD运行异常时如一直PENDING可通过kubectl describe查看异常信息

dongyunqi@mongodaddy:~/k8s$ kubectl describe pod ngx-dep-name-dcc8b7bfd-7lbrq | grep Events -A 100
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  34m   default-scheduler  Successfully assigned default/ngx-dep-name-dcc8b7bfd-7lbrq to mongomummy # pod分配的Node
  Normal  Pulled     34m   kubelet            Container image "nginx:alpine" already present on machine # 创建容器使用的镜像
  Normal  Created    34m   kubelet            Created container nginx # 创建容器显示的是容器的名称
  Normal  Started    34m   kubelet            Started container nginx

这里展示的正常如果是发生错误则在Message列会有对应的提示。如下是我从网上找的一个比较典型的错误信息

0/5 nodes are available: 1 node(s) had taint {node-role.kubernetes.io/master: }, that the pod didn't tolerate, 4 Insufficient memory.

0/5是说5个容器都不可用1 node(s) had taint {node-role.kubernetes.io/master: }其中一个是因为有污点 , 4 Insufficient memory 另外四个是因为内存不足了这样我们就可以对症下药了。