# kubectl命令说明
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## 1. kubectl命令介绍
kubectl的命令语法
```bash
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](https://kubernetes.io/cn/docs/user-guide/kubectl-overview/#%E8%B5%84%E6%BA%90%E7%B1%BB%E5%9E%8B)。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：
```bash
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：
```bash
* 要分组资源，如果它们都是相同的类型：`TYPE1 name1 name2 name<#>`.
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<#>`.
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：**
```bash
[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 --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
1. Node
2. Podes
3. Replication Controllers
4. Services
5. Namespace
6. Deployment
7. StatefulSet
**具体对象类型及缩写：**
```bash
* 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
```bash
kubectl get pod -o wide --namespace=
```
### 4.2 进入Pod
```bash
kubectl exec -it /bin/bash --namespace=
# 进入Pod中指定容器
kubectl exec -it -c /bin/bash --namespace=
```
### 4.3 删除Pod
```bash
kubectl delete pod --namespace=
# 强制删除Pod，当Pod一直处于Terminating状态
kubectl delete pod --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
```bash
$ 查看运行容器日志
kubectl logs --namespace=
$ 查看上一个挂掉的容器日志
kubectl logs -p --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**
```bash
# cordon命令
kubectl cordon
# 或者
kubectl patch node -p '{"spec":{"unschedulable":true}}'
```
**2. Node恢复**
```bash
# uncordon
kubectl uncordon
# 或者
kubectl patch node -p '{"spec":{"unschedulable":false}}'
```
### 5.2. kubectl label
**1. 固定Pod到指定机器**
```bash
kubectl label node namespace/=true
```
**2. 取消Pod固定机器**
```bash
kubectl label node namespace/-
```
### 5.3. 升级镜像
```bash
# 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
```bash
# 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
```bash
# 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
```bash
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
```bash
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。
```bash
$ 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。
```bash
kubectl get endpoints kube-scheduler --namespace=kube-system -o yaml
```
### 5.9. 修改副本数
```bash
kubectl scale deployment.v1.apps/nginx-deployment --replicas=10
```
### 5.10. 批量删除pod
```bash
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
```bash
# 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](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-instrumentation/logging.md) 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：
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