kubectl common examples

View class commands

# Get node and service version information
kubectl get nodes
# Get node and service version information and view additional information
kubectl get nodes -o wide

# Get the pod information. The default namespace is default
kubectl get pod
# Get the pod information, default namespace by default, and view additional information (such as the IP address of the pod and the node on which it runs)
kubectl get pod -o wide
# Gets the pod for the specified namespace
kubectl get pod -n kube-system
# Gets the specified pod in the specified namespace
kubectl get pod -n kube-system podName
# Gets the pod for all namespaces
kubectl get pod -A
# View the details of the pod and display it in yaml format or json format
kubectl get pods -o yaml
kubectl get pods -o json

# View the tag information of pod
kubectl get pod -A --show-labels
# Query the pod according to the Selector (label query)
kubectl get pod -A --selector="k8s-app=kube-dns"

# View environment variables for running pod
kubectl exec podName env
# View the log of the specified pod
kubectl logs -f --tail 500 -n kube-system kube-apiserver-k8s-master

# View service information for all namespaces
kubectl get svc -A
# View the service information of the specified namespace
kubectl get svc -n kube-system

# View component statuses information
kubectl get cs
# View all configmaps information
kubectl get cm -A
# View all service accounts information
kubectl get sa -A
# View all daemonsets information
kubectl get ds -A
# View all deployments information
kubectl get deploy -A
# View all replicasets information
kubectl get rs -A
# View all statefulsets information
kubectl get sts -A
# View all jobs information
kubectl get jobs -A
# View all ingresses information
kubectl get ing -A
# See what namespaces are available
kubectl get ns

# View the description of the pod
kubectl describe pod podName
kubectl describe pod -n kube-system kube-apiserver-k8s-master
# View the description of the specified deploy in the specified namespace
kubectl describe deploy -n kube-system coredns

# View the resource usage of node or pod
# heapster or metrics server support is required
kubectl top node
kubectl top pod

# View cluster information
kubectl cluster-info   or  kubectl cluster-info dump
# View the information of each component [172.16.1.110 is the master machine]
kubectl -s https://172.16.1.110:6443 get componentstatuses

Operation class Command

# Create resource
kubectl create -f xxx.yaml
# Application resources
kubectl apply -f xxx.yaml
# Application resources, all in this directory yaml, .yml, or json files will be used
kubectl apply -f <directory>
# Create test namespace
kubectl create namespace test

# Delete resource
kubectl delete -f xxx.yaml
kubectl delete -f <directory>
# Delete the specified pod
kubectl delete pod podName
# Deletes the specified pod for the specified namespace
kubectl delete pod -n test podName
# Delete other resources
kubectl delete svc svcName
kubectl delete deploy deployName
kubectl delete ns nsName
# Force delete
kubectl delete pod podName -n nsName --grace-period=0 --force
kubectl delete pod podName -n nsName --grace-period=1
kubectl delete pod podName -n nsName --now

# Edit resources
kubectl edit pod podName

Advanced command operation

# kubectl exec: enter the container started by pod
kubectl exec -it podName -n nsName /bin/sh    #Enter container
kubectl exec -it podName -n nsName /bin/bash  #Enter container

# kubectl label: add label value
kubectl label nodes k8s-node01 zone=north  #Adds a label to the specified node
kubectl label nodes k8s-node01 zone-       #Deletes a label for the specified node
kubectl label pod podName -n nsName role-name=test    #Label the specified pod
kubectl label pod podName -n nsName role-name=dev --overwrite  #Modify label value
kubectl label pod podName -n nsName role-name-        #Delete label

# Kubectl rolling upgrade; Via kubectl apply - F myapp-deployment-v1 Yaml start deploy
kubectl apply -f myapp-deployment-v2.yaml     #Rolling upgrade through profile
kubectl set image deploy/myapp-deployment myapp="registry.cn-beijing.aliyuncs.com/google_registry/myapp:v3"   #Scrolling through commands
kubectl rollout undo deploy/myapp-deployment perhaps kubectl rollout undo deploy myapp-deployment    #The pod rolls back to the previous version
kubectl rollout undo deploy/myapp-deployment --to-revision=2  #Rollback to the specified historical version

# kubectl scale: dynamic scaling
kubectl scale deploy myapp-deployment --replicas=5  # Dynamic scaling
kubectl scale --replicas=8 -f myapp-deployment-v2.yaml  #Dynamic scaling [scaling according to resource type and name, other configurations such as different image versions will not take effect]

The yaml file of deploy involved in rolling update and dynamic scaling above

[root@k8s-master deploy]# cat myapp-deployment-v1.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deployment
  labels:
    app: myapp
spec:
  replicas: 10
  # Focus on this field
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1
        ports:
        - containerPort: 80

[root@k8s-master deploy]#
[root@k8s-master deploy]# cat myapp-deployment-v2.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deployment
  labels:
    app: myapp
spec:
  replicas: 10
  # Focus on this field
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: registry.cn-beijing.aliyuncs.com/google_registry/myapp:v2
        ports:
        - containerPort: 80

kubectl syntax

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

Official website address: https://kubernetes.io/docs/reference/kubectl/overview/ 
kubectl flags: https://kubernetes.io/docs/reference/kubectl/kubectl/

explain:

1. command: Specifies the operation to be performed on one or more resources. For example: create, get, describe, delete, apply, etc

2. TYPE: Specifies the resource TYPE (such as pod, node, services, deployments, etc.). Resource types are case sensitive and can specify singular, plural or abbreviation forms. For example, the following command produces the same output:

1 kubectl get pod  -n kubernetes-dashboard
2 kubectl get pods -n kubernetes-dashboard
3 kubectl get po   -n kubernetes-dashboard

3. NAME: Specifies the NAME of the resource. Names are case sensitive. If the namespace is omitted, the details of the default namespace resources or the prompt: No resources found in default namespace.

# Example:
[root@k8s-master ~]# kubectl get pods
No resources found in default namespace.
[root@k8s-master ~]# kubectl get pods --all-namespaces  # Or kubectl get pods --A
NAMESPACE              NAME                                         READY   STATUS    RESTARTS   AGE
kube-system            coredns-6955765f44-c9zfh                     1/1     Running   8          6d7h
kube-system            coredns-6955765f44-lrz5q                     1/1     Running   8          6d7h
kube-system            etcd-k8s-master                              1/1     Running   9          6d7h
kube-system            kube-apiserver-k8s-master                    1/1     Running   9          6d7h
kube-system            kube-controller-manager-k8s-master           1/1     Running   8          6d7h
kube-system            kube-flannel-ds-amd64-dngrk                  1/1     Running   13         6d7h
kube-system            kube-flannel-ds-amd64-h4sn6                  1/1     Running   13         6d6h
kube-system            kube-flannel-ds-amd64-m92wp                  1/1     Running   11         6d6h
kube-system            kube-proxy-28dwj                             1/1     Running   9          6d6h
kube-system            kube-proxy-c875m                             1/1     Running   8          6d7h
kube-system            kube-proxy-stg6w                             1/1     Running   10         6d6h
kube-system            kube-scheduler-k8s-master                    1/1     Running   9          6d7h
kubernetes-dashboard   dashboard-metrics-scraper-7b8b58dc8b-nr5fz   1/1     Running   7          6d1h
kubernetes-dashboard   kubernetes-dashboard-755dcb9575-9kg7p        1/1     Running   9          6d1h
[root@k8s-master ~]# kubectl get service --all-namespaces  # Or kubectl get service -A
NAMESPACE              NAME                        TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)                  AGE
default                kubernetes                  ClusterIP   10.96.0.1       <none>        443/TCP                  6d7h
kube-system            kube-dns                    ClusterIP   10.96.0.10      <none>        53/UDP,53/TCP,9153/TCP   6d7h
kubernetes-dashboard   dashboard-metrics-scraper   ClusterIP   10.104.12.221   <none>        8000/TCP                 6d1h
kubernetes-dashboard   kubernetes-dashboard        NodePort    10.110.157.29   <none>        443:30001/TCP            6d1h

3. flags: specifies an optional flag. For example, you can use the - s or -- server ID to specify the address and port of the Kubernetes API server- n specify the namespace; wait.

Note: the flags you specify from the command line will override the default value and any corresponding environment variables. Highest priority.

4. When performing operations on multiple resources, you can specify each resource by TYPE [TYPE] and NAME [NAME], or you can specify one or more files.

Specify resources by type and name:

# View multiple resources in a resource type
[root@k8s-master ~]# kubectl get pod -n kube-system coredns-6955765f44-c9zfh kube-proxy-28dwj
NAME                       READY   STATUS    RESTARTS   AGE
coredns-6955765f44-c9zfh   1/1     Running   8          6d7h
kube-proxy-28dwj           1/1     Running   9          6d6h
[root@k8s-master ~]#
# View multiple resource types
[root@k8s-master ~]# kubectl get svc,node
NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   45h

NAME              STATUS   ROLES    AGE   VERSION
node/k8s-master   Ready    master   45h   v1.17.4
node/k8s-node01   Ready    <none>   45h   v1.17.4
node/k8s-node02   Ready    <none>   45h   v1.17.4

Specify a resource using one or more files: - F file1 - F File2 - f file < #>

1 # use YAML instead of JSON because YAML is easier to use, especially for configuration files.
2 kubectl get pod -f pod.yaml

command operation in kubectl syntax

The following table contains a short description and general syntax of common kubectl operations:

Some information can also be obtained on the command line through the kubectl -h command
Or see more details at:

1 https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands
2 https://kubernetes.io/docs/reference/kubectl/overview/#operations

Operation	Syntax	Description
create	kubectl create -f FILENAME [flags]	Create one or more resources from a file or standard input ★★★
expose	kubectl expose (-f FILENAME	TYPE NAME
run	kubectl run NAME –image=image [–env="key=value"] [–port=port] [–replicas=replicas] [–dry-run=bool] [–overrides=inline-json] [flags]	Run the specified image on the cluster ★★★
explain	kubectl explain [–recursive=false] [flags]	Obtain documents of various resources. For example, pods, nodes, services, etc. ★★★★★
get	kubectl get (-f FILENAME	TYPE [NAME
edit	kubectl edit (-f FILENAME	TYPE NAME
delete	kubectl delete (-f FILENAME	TYPE [NAME
rollout	kubectl rollout SUBCOMMAND [options]	Manage resources. Valid resource types include deployments, daemonsets, and statefulsets
scale	kubectl scale (-f FILENAME	TYPE NAME
autoscale	kubectl autoscale (-f FILENAME	TYPE NAME
cluster-info	kubectl cluster-info [flags]	Display cluster information, and display endpoint information about hosts and services in the cluster. ★★★
top	kubectl top node and kubectl top pod need heapster or metrics server support	Display resource (CPU / memory / storage) usage ★★★
cordon	kubectl cordon NODE [options]	Mark node as non schedulable
uncordon	kubectl uncordon NODE [options]	Mark node as schedulable
drain	kubectl drain NODE [options]	Exclude the specified node node to prepare for maintenance
taint	kubectl taint NODE NAME KEY_1=VAL_1:TAINT_EFFECT_1 ... KEY_N=VAL_N:TAINT_EFFECT_N [options]	Update stains on one or more nodes ★★
describe	kubectl describe (-f FILENAME	TYPE [NAME_PREFIX
logs	kubectl logs POD [-c CONTAINER] [–follow] [flags]	Print the log of a container in the pod ★★★★
exec	kubectl exec POD [-c CONTAINER] [-i] [-t] [flags] [– COMMAND [args...]]	Execute commands on the container in the pod or enter the pod container ★★★★
proxy	kubectl proxy [–port=PORT] [–www=static-dir] [–www-prefix=prefix] [–api-prefix=prefix] [flags]	Agent running Kubernetes API service
cp	kubectl cp [options]	Copy files and directories from the host to a container; Or copy files and directories from the container to the host ★★★
auth	kubectl auth [flags] [options]	Check authorization
apply	kubectl apply -f FILENAME [flags]	Apply the configuration to the resource through the content in the file name or stdin ★★★★
patch	kubectl patch (-f FILENAME	TYPE NAME
replace	kubectl replace -f FILENAME	Replace resources with files or stdin
rolling-update	kubectl rolling-update OLD_CONTROLLER_NAME ([NEW_CONTROLLER_NAME] –image=NEW_CONTAINER_IMAGE	-f NEW_CONTROLLER_SPEC) [flags]
label	kubectl label (-f FILENAME	TYPE NAME
annotate	kubectl annotate (-f FILENAME	TYPE NAME
api-resources	kubectl api-resources [flags] [options]	Print supported API resources ★★★
api-versions	kubectl api-versions [flags]	List available API versions ★★★
config	kubectl config SUBCOMMAND [flags]	Modify the kubeconfig file. For more information, see each subcommand
plugin	kubectl plugin [flags] [options]	Provides utilities to interact with plug-ins
version	kubectl version [–client] [flags]	Displays the version of Kubernetes running on the client and server ★★★

TYPE resource in kubectl syntax

The following table contains a list of commonly used resource types and their abbreviations and aliases.

It can also be obtained through kubectl API resources on the command line.

Resource Name	Short Names	Namespaced	Resource Kind
bindings		TRUE	Binding
componentstatuses	cs	FALSE	ComponentStatus
configmaps	cm	TRUE	ConfigMap
endpoints	ep	TRUE	Endpoints
events	ev	TRUE	Event
limitranges	limits	TRUE	LimitRange
namespaces	ns	FALSE	Namespace
nodes	no	FALSE	Node
persistentvolumeclaims	pvc	TRUE	PersistentVolumeClaim
persistentvolumes	pv	FALSE	PersistentVolume
pods	po	TRUE	Pod
podtemplates		TRUE	PodTemplate
replicationcontrollers	rc	TRUE	ReplicationController
resourcequotas	quota	TRUE	ResourceQuota
secrets		TRUE	Secret
serviceaccounts	sa	TRUE	ServiceAccount
services	svc	TRUE	Service
mutatingwebhookconfigurations		FALSE	MutatingWebhookConfiguration
validatingwebhookconfigurations		FALSE	ValidatingWebhookConfiguration
customresourcedefinitions	crd, crds	FALSE	CustomResourceDefinition
apiservices		FALSE	APIService
controllerrevisions		TRUE	ControllerRevision
daemonsets	ds	TRUE	DaemonSet
deployments	deploy	TRUE	Deployment
replicasets	rs	TRUE	ReplicaSet
statefulsets	sts	TRUE	StatefulSet
tokenreviews		FALSE	TokenReview
localsubjectaccessreviews		TRUE	LocalSubjectAccessReview
selfsubjectaccessreviews		FALSE	SelfSubjectAccessReview
selfsubjectrulesreviews		FALSE	SelfSubjectRulesReview
subjectaccessreviews		FALSE	SubjectAccessReview
horizontalpodautoscalers	hpa	TRUE	HorizontalPodAutoscaler
cronjobs	cj	TRUE	CronJob
jobs		TRUE	Job
certificatesigningrequests	csr	FALSE	CertificateSigningRequest
leases		TRUE	Lease
endpointslices		TRUE	EndpointSlice
events	ev	TRUE	Event
ingresses	ing	TRUE	Ingress
networkpolicies	netpol	TRUE	NetworkPolicy
runtimeclasses		FALSE	RuntimeClass
poddisruptionbudgets	pdb	TRUE	PodDisruptionBudget
podsecuritypolicies	psp	FALSE	PodSecurityPolicy
clusterrolebindings		FALSE	ClusterRoleBinding
clusterroles		FALSE	ClusterRole
rolebindings		TRUE	RoleBinding
roles		TRUE	Role
priorityclasses	pc	FALSE	PriorityClass
csidrivers		FALSE	CSIDriver
csinodes		FALSE	CSINode
storageclasses	sc	FALSE	StorageClass
volumeattachments		FALSE	VolumeAttachment

kubectl output options

Format output

The default output format for all kubectl commands is human readable plain text.

To output details to a terminal window in a specific format, you can add the - o or -- output ID to the supported kubectl command.

grammar

kubectl [command] [TYPE] [NAME] -o <output_format>

According to kubectl operation, the following output formats are supported:

Output format	Description
-o custom-columns=	Print the table using a comma separated list of custom columns
-o custom-columns-file=	Print the table using a custom column template in the file
-o json	Output an API object in JSON format
-o jsonpath=	Print the fields defined in the jsonpath expression
-o jsonpath-file=	Print the fields defined by the jsonpath expression through the file
-o name	Print only the resource name and nothing else
-o wide	Output in plain text format with additional information. For pods, include the node name
-o yaml	Output an API object in YAML format

Example

wide example

[root@k8s-master ~]# kubectl get pod
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   1/1     Running   1          28h
[root@k8s-master ~]#
[root@k8s-master ~]# kubectl get pod -o wide
NAME         READY   STATUS    RESTARTS   AGE   IP           NODE         NOMINATED NODE   READINESS GATES
nginx-demo   1/1     Running   1          28h   10.244.3.9   k8s-node01   <none>           <none>

yaml example

[root@k8s-master ~]# kubectl get pod
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   1/1     Running   1          28h
[root@k8s-master ~]#
[root@k8s-master ~]# kubectl get pod -o yaml
apiVersion: v1
items:
- apiVersion: v1
  kind: Pod
  metadata:
    annotations:
..................

json example

[root@k8s-master ~]# kubectl get pod
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   1/1     Running   1          28h
[root@k8s-master ~]#
[root@k8s-master ~]# kubectl get pod -o json
{
    "apiVersion": "v1",
    "items": [
        {
            "apiVersion": "v1",
            "kind": "Pod",
            "metadata": {
                "annotations": {
..................

name example

[root@k8s-master ~]# kubectl get pod
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   1/1     Running   1          28h
[root@k8s-master ~]#
[root@k8s-master ~]# kubectl get pod -o name
pod/nginx-demo

Custom columns example

[root@k8s-master ~]# kubectl get pod
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   1/1     Running   1          29h
[root@k8s-master ~]#
[root@k8s-master ~]# kubectl get pods -o custom-columns=NAME:.metadata.name,UID:.metadata.uid,imageName:.spec.containers[0].image
NAME         UID                                    imageName
nginx-demo   08121fc6-969b-4b4e-9aa4-b990a5d02148   registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17

Description: custom columns = key: value; Where key means listed; Value indicates the information to be displayed. This value information can be obtained through - o json or - o yaml.

Custom columns file example

[root@k8s-master test]# kubectl get pod
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   1/1     Running   0          80s
[root@k8s-master test]#
# List and data source to display
[root@k8s-master test]# cat custom-col.conf
NAME          UID          imageName                containerPort
metadata.name metadata.uid spec.containers[0].image spec.containers[0].ports[0].containerPort
[root@k8s-master test]#
[root@k8s-master test]# kubectl get pod -o custom-columns-file=custom-col.conf
NAME         UID                                    imageName                                                     containerPort
nginx-demo   769dc3f4-2ffc-407c-a351-56b74ddaba4c   registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17   80

jsonpath example

[root@k8s-master test]# kubectl get pods
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   1/1     Running   0          13m
[root@k8s-master test]#
[root@k8s-master test]# kubectl get pods -o jsonpath='{.items[0].metadata.name},{.items[0].spec.containers[0].image}'
nginx-demo,registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17

Jsonpath file example

[root@k8s-master test]# kubectl get pod
NAME         READY   STATUS    RESTARTS   AGE
nginx-demo   1/1     Running   0          16m
[root@k8s-master test]#
# Data source to display
[root@k8s-master test]# cat custom-json.conf
{.items[0].metadata.name},{.items[0].spec.containers[0].image},{.items[0].spec.containers[0].ports[0].containerPort}
[root@k8s-master test]#
[root@k8s-master test]# kubectl get pod -o jsonpath-file=custom-json.conf
nginx-demo,registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17,80

Related reading

1,Overview of kubectl on the official website

2,Official website kubectl [flags]

3,Details of kubectl commands on the official website

complete!