kubectl命令说明

本文个人博客地址：http://www.huweihuang.com/article/kubernetes/kubernetes-commands/

1. kubectl命令介绍

kubectl的命令语法

kubectl [command] [TYPE] [NAME] [flags]

其中command，TYPE，NAME，和flags分别是：

command: 指定要在一个或多个资源进行操作，例如create，get，describe，delete。
TYPE：指定资源类型。资源类型区分大小写，您可以指定单数，复数或缩写形式。例如，以下命令产生相同的输出：
```
kubectl get pod pod1  
kubectl get pods pod1 
kubectl get po pod1
```

NAME：指定资源的名称。名称区分大小写。如果省略名称，则会显示所有资源的详细信息,比如$ kubectl get pods。

按类型和名称指定多种资源：

* 要分组资源，如果它们都是相同的类型：`TYPE1 name1 name2 name<#>`.<br/>
例: `$ kubectl get pod example-pod1 example-pod2`

* 要分别指定多种资源类型:  `TYPE1/name1 TYPE1/name2 TYPE2/name3 TYPE<#>/name<#>`.<br/>
例: `$ kubectl get pod/example-pod1 replicationcontroller/example-rc1`

flags：指定可选标志。例如，您可以使用-s或--serverflags来指定Kubernetes API服务器的地址和端口。

更多命令介绍：

[root@node5 ~]# kubectl
kubectl controls the Kubernetes cluster manager.

Find more information at https://github.com/kubernetes/kubernetes.

Basic Commands (Beginner):
  create         Create a resource from a file or from stdin.
  expose         Take a replication controller, service, deployment or pod and expose it as a new Kubernetes Service
  run            Run a particular image on the cluster
  set            Set specific features on objects
  run-container  Run a particular image on the cluster. This command is deprecated, use "run" instead

Basic Commands (Intermediate):
  get            Display one or many resources
  explain        Documentation of resources
  edit           Edit a resource on the server
  delete         Delete resources by filenames, stdin, resources and names, or by resources and label selector

Deploy Commands:
  rollout        Manage the rollout of a resource
  rolling-update Perform a rolling update of the given ReplicationController
  scale          Set a new size for a Deployment, ReplicaSet, Replication Controller, or Job
  autoscale      Auto-scale a Deployment, ReplicaSet, or ReplicationController

Cluster Management Commands:
  certificate    Modify certificate resources.
  cluster-info   Display cluster info
  top            Display Resource (CPU/Memory/Storage) usage.
  cordon         Mark node as unschedulable
  uncordon       Mark node as schedulable
  drain          Drain node in preparation for maintenance
  taint          Update the taints on one or more nodes

Troubleshooting and Debugging Commands:
  describe       Show details of a specific resource or group of resources
  logs           Print the logs for a container in a pod
  attach         Attach to a running container
  exec           Execute a command in a container
  port-forward   Forward one or more local ports to a pod
  proxy          Run a proxy to the Kubernetes API server
  cp             Copy files and directories to and from containers.
  auth           Inspect authorization

Advanced Commands:
  apply          Apply a configuration to a resource by filename or stdin
  patch          Update field(s) of a resource using strategic merge patch
  replace        Replace a resource by filename or stdin
  convert        Convert config files between different API versions

Settings Commands:
  label          Update the labels on a resource
  annotate       Update the annotations on a resource
  completion     Output shell completion code for the specified shell (bash or zsh)

Other Commands:
  api-versions   Print the supported API versions on the server, in the form of "group/version"
  config         Modify kubeconfig files
  help           Help about any command
  plugin         Runs a command-line plugin
  version        Print the client and server version information

Use "kubectl <command> --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).

2. 操作的常用资源对象

Node
Podes
Replication Controllers
Services
Namespace
Deployment
StatefulSet

具体对象类型及缩写：

  * all
  * certificatesigningrequests (aka 'csr')
  * clusterrolebindings
  * clusterroles
  * componentstatuses (aka 'cs')
  * configmaps (aka 'cm')
  * controllerrevisions
  * cronjobs
  * customresourcedefinition (aka 'crd')
  * daemonsets (aka 'ds')
  * deployments (aka 'deploy')
  * endpoints (aka 'ep')
  * events (aka 'ev')
  * horizontalpodautoscalers (aka 'hpa')
  * ingresses (aka 'ing')
  * jobs
  * limitranges (aka 'limits')
  * namespaces (aka 'ns')
  * networkpolicies (aka 'netpol')
  * nodes (aka 'no')
  * persistentvolumeclaims (aka 'pvc')
  * persistentvolumes (aka 'pv')
  * poddisruptionbudgets (aka 'pdb')
  * podpreset
  * pods (aka 'po')
  * podsecuritypolicies (aka 'psp')
  * podtemplates
  * replicasets (aka 'rs')
  * replicationcontrollers (aka 'rc')
  * resourcequotas (aka 'quota')
  * rolebindings
  * roles
  * secrets
  * serviceaccounts (aka 'sa')
  * services (aka 'svc')
  * statefulsets (aka 'sts')
  * storageclasses (aka 'sc')

3. kubectl命令分类[command]

3.1 增

1）create:[Create a resource by filename or stdin]

2）run:[ Run a particular image on the cluster]

3）apply:[Apply a configuration to a resource by filename or stdin]

4）proxy:[Run a proxy to the Kubernetes API server ]

3.2 删

1）delete:[Delete resources ]

3.3 改

1）scale:[Set a new size for a Replication Controller]

2）exec:[Execute a command in a container]

3）attach:[Attach to a running container]

4）patch:[Update field(s) of a resource by stdin]

5）edit:[Edit a resource on the server]

6） label:[Update the labels on a resource]

7）annotate:[Auto-scale a replication controller]

8）replace:[Replace a resource by filename or stdin]

9）config:[config modifies kubeconfig files]

3.4 查

1）get:[Display one or many resources]

2）describe:[Show details of a specific resource or group of resources]

3）log:[Print the logs for a container in a pod]

4）cluster-info:[Display cluster info]

5） version:[Print the client and server version information]

6）api-versions:[Print the supported API versions]

4. Pod相关命令

4.1 查询Pod

kubectl get pod -o wide --namespace=<NAMESPACE>

4.2 进入Pod

kubectl exec -it <PodName> /bin/bash --namespace=<NAMESPACE>

# 进入Pod中指定容器
kubectl exec -it <PodName> -c <ContainerName> /bin/bash --namespace=<NAMESPACE>

4.3 删除Pod

kubectl delete pod <PodName> --namespace=<NAMESPACE>

# 强制删除Pod，当Pod一直处于Terminating状态
kubectl delete pod <PodName> --namespace=<NAMESPACE> --force --grace-period=0

# 删除某个namespace下某个类型的所有对象
kubectl delete deploy --all --namespace=test

4.4 日志查看

$ 查看运行容器日志 
kubectl logs <PodName> --namespace=<NAMESPACE>
$ 查看上一个挂掉的容器日志 
kubectl logs <PodName> -p --namespace=<NAMESPACE>

5. 常用命令

5.1. Node隔离与恢复

说明：Node设置隔离之后，原先运行在该Node上的Pod不受影响，后续的Pod不会调度到被隔离的Node上。

1. Node隔离

# cordon命令
kubectl cordon <NodeName>
# 或者
kubectl patch node <NodeName> -p '{"spec":{"unschedulable":true}}'

2. Node恢复

# uncordon
kubectl uncordon <NodeName>
# 或者
kubectl patch node <NodeName> -p '{"spec":{"unschedulable":false}}'

5.2. kubectl label

1. 固定Pod到指定机器

kubectl label node <NodeName> namespace/<NAMESPACE>=true

2. 取消Pod固定机器

kubectl label node <NodeName> namespace/<NAMESPACE>-

5.3. 升级镜像

# 升级镜像
kubectl set image deployment/nginx nginx=nginx:1.15.12 -n nginx
# 查看滚动升级情况
kubectl rollout status deployment/nginx  -n nginx

5.4. 调整资源值

# 调整指定容器的资源值
kubectl set resources sts nginx-0 -c=agent --limits=memory=512Mi -n nginx

5.5. 调整readiness probe

# 批量查看readiness probe timeoutSeconds
kubectl get statefulset -o=jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.spec.template.spec.containers[0].readinessProbe.timeoutSeconds}{"\n"}{end}'

# 调整readiness probe timeoutSeconds参数
kubectl patch statefulset nginx-sts --type='json' -p='[{"op": "replace", "path": "/spec/template/spec/containers/0/readinessProbe/timeoutSeconds", "value":5}]' -n nginx

5.6. 调整tolerations属性

kubectl patch statefulset nginx-sts --patch '{"spec": {"template": {"spec": {"tolerations": [{"effect": "NoSchedule","key": "dedicated","operator": "Equal","value": "nginx"}]}}}}' -n nginx

5.7. 查看所有节点的IP

kubectl get nodes -o=jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.status.addresses[0].address}{"\n"}{end}'

5.8. 查看当前k8s组件leader节点

当k8s集群高可用部署的时候，kube-controller-manager和kube-scheduler只能一个服务处于实际逻辑运行状态，通过参数--leader-elect=true来开启选举操作。以下提供查询leader节点的命令。

$ kubectl get endpoints kube-controller-manager --namespace=kube-system  -o yaml

apiVersion: v1
kind: Endpoints
metadata:
  annotations:
    control-plane.alpha.kubernetes.io/leader: '{"holderIdentity":"xxx.xxx.xxx.xxx_6537b938-7f5a-11e9-8487-00220d338975","leaseDurationSeconds":15,"acquireTime":"2019-05-26T02:03:18Z","renewTime":"2019-05-26T02:06:08Z","leaderTransitions":1}'
  creationTimestamp: "2019-05-26T01:52:39Z"
  name: kube-controller-manager
  namespace: kube-system
  resourceVersion: "1965"
  selfLink: /api/v1/namespaces/kube-system/endpoints/kube-controller-manager
  uid: f1755fc5-7f58-11e9-b4c4-00220d338975

以上表示"holderIdentity":"xxx.xxx.xxx.xxx为kube-controller-manager的leader节点。

同理，可以通过以下命令查看kube-scheduler的leader节点。

kubectl get endpoints kube-scheduler --namespace=kube-system  -o yaml

5.9. 修改副本数

kubectl scale deployment.v1.apps/nginx-deployment --replicas=10

5.10. 批量删除pod

kubectl get po -n default |grep Evicted |awk '{print $1}' |xargs -I {} kubectl delete po  {} -n default

5.11. 各种查看命令

# 不使用外部工具来输出解码后的 Secret
kubectl get secret my-secret -o go-template='{{range $k,$v := .data}}{{"### "}}{{$k}}{{"\n"}}{{$v|base64decode}}{{"\n\n"}}{{end}}'

# 列出事件（Events），按时间戳排序
kubectl get events --sort-by=.metadata.creationTimestamp

6. kubectl日志级别

Kubectl 日志输出详细程度是通过 -v 或者 --v 来控制的，参数后跟一个数字表示日志的级别。 Kubernetes 通用的日志习惯和相关的日志级别在这里有相应的描述。

详细程度

描述

--v=0

用于那些应该始终对运维人员可见的信息，因为这些信息一般很有用。

--v=1

如果您不想要看到冗余信息，此值是一个合理的默认日志级别。

--v=2

输出有关服务的稳定状态的信息以及重要的日志消息，这些信息可能与系统中的重大变化有关。这是建议大多数系统设置的默认日志级别。

--v=3

包含有关系统状态变化的扩展信息。

--v=4

包含调试级别的冗余信息。

--v=5

跟踪级别的详细程度。

--v=6

显示所请求的资源。

--v=7

显示 HTTP 请求头。

--v=8

显示 HTTP 请求内容。

--v=9

显示 HTTP 请求内容而且不截断内容。

参考文章：

https://kubernetes.io/docs/reference/kubectl/overview/
https://kubernetes.io/docs/tasks/access-application-cluster/configure-access-multiple-clusters/
https://kubernetes.io/zh/docs/reference/kubectl/cheatsheet/

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