Summary of Kubectl commands that you must know for operation and maintenance

kubectl common command guide

The Kubectl command is the most direct way to operate a kubernetes cluster. Especially operation and maintenance personnel need to have a detailed grasp of these commands.

Kubectl autocompletion

# setup autocomplete in bash, bash-completion package should be installed first.$ source <(kubectl completion bash)  # setup autocomplete in zsh$ source <(kubectl completion zsh)

Kubectl context and configuration

Set up the kubernetes cluster for kubectl command interaction and modify the configuration information. See Using kubeconfig files for cross-cluster verification for details about configuration files.

# 显示合并后的 kubeconfig 配置$ kubectl config view # 同时使用多个 kubeconfig 文件并查看合并后的配置$ KUBECONFIG=~/.kube/config:~/.kube/kubconfig2 kubectl config view# 获取 e2e 用户的密码$ kubectl config view -o jsonpath='{.users[?(@.name == "e2e")].user.password}'# 显示当前的上下文$ kubectl config current-context    # 设置默认上下文为 my-cluster-name$ kubectl config use-context my-cluster-name  # 向 kubeconf 中增加支持基本认证的新集群$ kubectl config set-credentials kubeuser/foo.kubernetes.com --username=kubeuser --password=kubepassword# 使用指定的用户名和 namespace 设置上下文$ kubectl config set-context gce --user=cluster-admin --namespace=foo \  && kubectl config use-context gce

Create object

Kubernetes manifest files can be defined in json or yaml format. It can be   extended with .yaml, .yml, or  ..json

# 创建资源$ kubectl create -f ./my-manifest.yaml     # 使用多个文件创建资源$ kubectl create -f ./my1.yaml -f ./my2.yaml   # 使用目录下的所有清单文件来创建资源$ kubectl create -f ./dir    # 使用 url 来创建资源$ kubectl create -f https://git.io/vPieo  # 启动一个 nginx 实例$ kubectl run nginx --image=nginx   # 获取 pod 和 svc 的文档$ kubectl explain pods,svc                      # 从 stdin 输入中创建多个 YAML 对象$ cat <<EOF | kubectl create -f -apiVersion: v1kind: Podmetadata:  name: busybox-sleepspec:  containers:  - name: busybox    image: busybox    args:    - sleep    - "1000000"---apiVersion: v1kind: Podmetadata:  name: busybox-sleep-lessspec:  containers:  - name: busybox    image: busybox    args:    - sleep    - "1000"EOF# 创建包含几个 key 的 Secret$ cat <<EOF | kubectl create -f -apiVersion: v1kind: Secretmetadata:  name: mysecrettype: Opaquedata:  password: $(echo "s33msi4" | base64)  username: $(echo "jane" | base64)EOF

Display and find resources

# Get commands with basic output# 列出所有 namespace 中的所有 service$ kubectl get services            
# 列出所有 namespace 中的所有 pod$ kubectl get pods --all-namespaces  
# 列出所有 pod 并显示详细信息$ kubectl get pods -o wide      
# 列出指定 deployment$ kubectl get deployment my-dep      
# 列出该 namespace 中的所有 pod 包括未初始化的$ kubectl get pods --include-uninitialized      
# 使用详细输出来描述命令$ kubectl describe nodes my-node$ kubectl describe pods my-pod
# List Services Sorted by Name$ kubectl get services --sort-by=.metadata.name 
# 根据重启次数排序列出 pod$ kubectl get pods --sort-by='.status.containerStatuses[0].restartCount'
# 获取所有具有 app=cassandra 的 pod 中的 version 标签$ kubectl get pods --selector=app=cassandra rc -o \  jsonpath='{.items[*].metadata.labels.version}'
# 获取所有节点的 ExternalIP$ kubectl get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="ExternalIP")].address}'
# 列出属于某个 PC 的 Pod 的名字# “jq”命令用于转换复杂的 jsonpath，参考 https://stedolan.github.io/jq/$ sel=${$(kubectl get rc my-rc --output=json | jq -j '.spec.selector | to_entries | .[] | "\(.key)=\(.value),"')%?}$ echo $(kubectl get pods --selector=$sel --output=jsonpath={.items..metadata.name})
# 查看哪些节点已就绪$ JSONPATH='{range .items[*]}{@.metadata.name}:{range @.status.conditions[*]}{@.type}={@.status};{end}{end}' \ && kubectl get nodes -o jsonpath="$JSONPATH" | grep "Ready=True"
# 列出当前 Pod 中使用的 Secret$ kubectl get pods -o json | jq '.items[].spec.containers[].env[]?.valueFrom.secretKeyRef.name' | grep -v null | sort | uniq

Update resources

$ kubectl rolling-update frontend-v1 -f frontend-v2.json           # 滚动更新 pod frontend-v1$ kubectl rolling-update frontend-v1 frontend-v2 --image=image:v2  # 更新资源名称并更新镜像$ kubectl rolling-update frontend --image=image:v2                 # 更新 frontend pod 中的镜像$ kubectl rolling-update frontend-v1 frontend-v2 --rollback        # 退出已存在的进行中的滚动更新$ cat pod.json | kubectl replace -f -                              # 基于 stdin 输入的 JSON 替换 pod# 强制替换，删除后重新创建资源。会导致服务中断。$ kubectl replace --force -f ./pod.json# 为 nginx RC 创建服务，启用本地 80 端口连接到容器上的 8000 端口$ kubectl expose rc nginx --port=80 --target-port=8000# 更新单容器 pod 的镜像版本（tag）到 v4$ kubectl get pod mypod -o yaml | sed 's/\(image: myimage\):.*$/\1:v4/' | kubectl replace -f -# 添加标签$ kubectl label pods my-pod new-label=awesome         # 添加注解$ kubectl annotate pods my-pod icon-url=http://goo.gl/XXBTWq   # 自动扩展 deployment “foo”$ kubectl autoscale deployment foo --min=2 --max=10

patch resources

Merge patches and patch resources using policies. ​​​​​

# 部分更新节点kubectl patch node k8s-node-1 -p '{"spec":{"unschedulable":true}}' # 更新容器镜像；spec.containers[*].name 是必须的，因为这是合并的关键字$ kubectl patch pod valid-pod -p '{"spec":{"containers":[{"name":"kubernetes-serve-hostname","image":"new image"}]}}'# 使用具有位置数组的 json 补丁更新容器镜像$ kubectl patch pod valid-pod --type='json' -p='[{"op": "replace", "path": "/spec/containers/0/image", "value":"new image"}]'# 使用具有位置数组的 json 补丁禁用 deployment 的 livenessProbe$ kubectl patch deployment valid-deployment  --type json   -p='[{"op": "remove", "path": "/spec/template/spec/containers/0/livenessProbe"}]'

Edit resources

Edit any API resource in the editor. ​​​​​​​

# 编辑名为 docker-registry 的 service$ kubectl edit svc/docker-registry           # 使用其它编辑器$ KUBE_EDITOR="nano" kubectl edit svc/docker-registry

Scale resources

# Scale a replicaset named 'foo' to 3$ kubectl scale --replicas=3 rs/foo       # Scale a resource specified in "foo.yaml" to 3$ kubectl scale --replicas=3 -f foo.yaml     # If the deployment named mysql's current size is 2, scale mysql to 3$ kubectl scale --current-replicas=2 --replicas=3 deployment/mysql  # Scale multiple replication controllers$ kubectl scale --replicas=5 rc/foo rc/bar rc/baz

Delete resources​​​​​​​

# 删除 pod.json 文件中定义的类型和名称的 pod$ kubectl delete -f ./pod.json        # 删除名为“baz”的 pod 和名为“foo”的 service$ kubectl delete pod,service baz foo      # 删除具有 name=myLabel 标签的 pod 和 serivce$ kubectl delete pods,services -l name=myLabel       # 删除具有 name=myLabel 标签的 pod 和 service，包括尚未初始化的$ kubectl delete pods,services -l name=myLabel --include-uninitialized   # 删除 my-ns namespace 下的所有 pod 和 serivce包$ kubectl -n my-ns delete po,svc --all

Interact with running Pods

# dump 输出 pod 的日志（stdout）$ kubectl logs my-pod   # dump 输出 pod 中容器的日志（stdout，pod 中有多个容器的情况下使用）$ kubectl logs my-pod -c my-container      # 流式输出 pod 的日志（stdout）$ kubectl logs -f my-pod             # 流式输出 pod 中容器的日志（stdout，pod 中有多个容器的情况下使用）$ kubectl logs -f my-pod -c my-container# 交互式 shell 的方式运行 pod$ kubectl run -i --tty busybox --image=busybox -- sh   # 连接到运行中的容器$ kubectl attach my-pod -i    # 转发 pod 中的 6000 端口到本地的 5000 端口$ kubectl port-forward my-pod 5000:6000     # 在已存在的容器中执行命令（只有一个容器的情况下）$ kubectl exec my-pod -- ls /          # 在已存在的容器中执行命令（pod 中有多个容器的情况下）$ kubectl exec my-pod -c my-container -- ls /    # 显示指定 pod 和容器的指标度量$ kubectl top pod POD_NAME --containers

Interact with nodes and clusters

# 标记 my-node 不可调度$ kubectl cordon my-node       # 清空 my-node 以待维护$ kubectl drain my-node    # 标记 my-node 可调度$ kubectl uncordon my-node              # 显示 my-node 的指标度量$ kubectl top node my-node    $ kubectl cluster-info           # 将当前集群状态输出到 stdout$ kubectl cluster-info dump                                                                # 将当前集群状态输出到 /path/to/cluster-state$ kubectl cluster-info dump --output-directory=/path/to/cluster-state  # 如果该键和影响的污点（taint）已存在，则使用指定的值替换$ kubectl taint nodes foo dedicated=special-user:NoSchedule

set command

Configure some specific resources of the application, and you can also modify the existing resources of the application

Use  kubectl set --helpView, its subcommands, env, image, resources, selector, serviceaccount, subject.

语法：resources (-f FILENAME | TYPE NAME) ([—limits=LIMITS & —requests=REQUESTS]

kubectl set resources command

This command is used to set some scope restrictions on resources.

The Pod in the resource object can specify the computing resource requirements (CPU - unit m, memory - unit Mi), that is, the minimum resource requests used (Requests), and the maximum resource requirements (Limits). The Pod will guarantee the use of the set number of resources. scope.

For each Pod resource, if a Limits value is specified and Requests is omitted, Requests defaults to the Limits value.

可用资源对象包括(支持大小写)：replicationcontroller、deployment、daemonset、job、replicaset。

For example:

# 将deployment的nginx容器cpu限制为“200m”，将内存设置为“512Mi”$ kubectl set resources deployment nginx -c=nginx --limits=cpu=200m,memory=512Mi# 设置所有nginx容器中 Requests和Limits$ kubectl set resources deployment nginx --limits=cpu=200m,memory=512Mi --requests=cpu=100m,memory=256Mi# 删除nginx中容器的计算资源值$ kubectl set resources deployment nginx --limits=cpu=0,memory=0 --requests=cpu=0,memory=0

kubectl set selector command

Set the resource's  selector(selector). If a selector already exists before calling the "set selector" command, the newly created selector will overwrite the original selector.

selectorIt must start with a letter or number and contain up to 63 characters. You can use: letters, numbers, hyphens " - " , dot "." and underscore " _ ". If --resource-version is specified, the update will use this resource version, otherwise the existing resource version will be used.

Note: Currently the selector command can only be used for Service objects.

语法：selector (-f FILENAME | TYPE NAME) EXPRESSIONS [—resource-version=version]

kubectl set image command

Container image used to update existing resources.

Available resource objects include: pod (po), replicationcontroller (rc), deployment (deploy), daemonset (ds), job, replicaset (rs).

语法：image (-f FILENAME | TYPE NAME) CONTAINER_NAME_1=CONTAINER_IMAGE_1 … CONTAINER_NAME_N=CONTAINER_IMAGE_N

# 将deployment中的nginx容器镜像设置为“nginx：1.9.1”$ kubectl set image deployment/nginx busybox=busybox nginx=nginx:1.9.1# 所有deployment和rc的nginx容器镜像更新为“nginx：1.9.1”$ kubectl set image deployments,rc nginx=nginx:1.9.1 --all# 将daemonset abc的所有容器镜像更新为“nginx：1.9.1”$ kubectl set image daemonset abc *=nginx:1.9.1# 从本地文件中更新nginx容器镜像$ kubectl set image -f path/to/file.yaml nginx=nginx:1.9.1 --local -o yaml

Resource Type

The following table lists all supported types and abbreviated aliases in kubernetes.

Formatted output

To output detailed information to the terminal window in a specific format, you can  kubectl add  the -o or  -output flag to the command.

Kubectl verbose output and debugging

Use  -v the or  --v flag followed by an integer to specify the log level.

Source: https://zhuanlan.zhihu.com/p/394967586