Kubernetes -- detailed usage of kubectl command line tool

kubectl As a client CLI Tools , You can use the command line to Kubernetes Cluster operation .

kubectl Usage overview

kubectl The syntax of the command line is as follows ：

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

• command： Sons command , Used to operate Kubernetes Commands for cluster resource objects , for example create、delete、describe、get、apply etc.

• TYPE： The type of resource object , Case sensitive , Can be in singular form 、 Plural or abbreviated identification

  • kubectl get pod pod1
  • kubectl get pods pod1
  • kubectl get po pod1

• NAME： The name of the resource object , Case sensitive . If you do not specify a name , The system will return to belong to TYPE A list of all the objects of

• flags：kubectl Optional parameters to the subcommand , For example, using -s Appoint apiserver Of URL Address without default value

kubectl The types of resource objects that can be operated are shown in the following table ：

The name of the resource object	abbreviation
clusters
componentstatuses	cs
configmaps	cm
daemonsets	ds
deployments	deploy
endpoiints	ep
events	ev
horizontalpodautoscalers	hpa
ingresses	ing
Jobs
limitranges	limits
nodes	no
namespaces	ns
networkpolicies
nodes	no
statefulsets
persistentvolumeclaims	pvc
persistentvolumes	pv
pods	po
podsecuritypolicies	psp
podtemplates
replicasets	rs
replicationcontrollers	rc
resourcequotas	quota
cronjob
secrets
serviceaccounts
services	svc
storageclasses	sc
thirdpartyresources

You can also operate on multiple resource objects at the same time in one command line , With many TYPE and NAME The combination logo of , as follows ：

Get multiple Pod Information about ：
kubectl get pods pod1 pod2

Get information about multiple objects ：
kubectl get pod/pod1 rc/rc1

Apply more than one at the same time yaml file , With many -f file parameter ：
kubectl get pod -f pod1.yaml -f pod2.yaml
kubectl create -f pod1.yaml -f rc1.yaml -f service1.yaml

kubectl The subcommand explains

Sons command	grammar	explain
annotate	kubectl annotate(-f FILENAME | TYPE NAME | TYPE/NAME ) KEY_1=VAL_1 ... KEY_N=VAL_N [--overwrite][--all] [--resource-version=version][flag]	Add or update the annotation Information
api-versions	kubectl api-versions [flags]	List the current system supports API Version list , The format is "group/version"
apply	kubectl apply -f FILENAME [flags]	From the configuration file or stdin Update the configuration of resource objects in
attach	kubectl attach POD -c CONTAINER [flags]	Attach to a running container
autoscale	kubectl autoscale (-f FILENAME | TYPE NAME | TYPE/NAME) [--min=MINPODS] --max=MAXPODS [--cpu-percent=CPU][flags]	Yes Deployment、ReplicaSet or ReplicationController Set the horizontal automatic expansion and shrinkage
cluster_info	kubectl cluster_info [flags]	Show clusters Master And information about the built-in Services
completion	kubectl completion SHELL [flags]	Output shell Command execution result code (bash or zsh)
config	kubectl config SUBCOMMAND [flags]	modify cubeconfig file
convert	kubectl convert -f FILENAME [flags]	Convert configuration files to different API edition
cordon	kubectl cordon NODE [flags]	take Node Marked as unschedulable, namely " Isolation " Out of the cluster scheduling range
create	kubectl create -f FILENAME [flags]	From the configuration file or stdin Create resource objects in
delete	kubectl delete (-f FILENAME | TYPE [NAME | /NAME | -l label | -all])[flags]	According to the configuration file 、ST set 、 Resource name or label selector Delete resource object
describe	kubectl describe (-f FILENAME | TYPE [NAME_PREFIX | /NAME | -l label])[flags]	Describe the details of one or more resource objects
drain	kubectl drain NODE [flags]	First of all, will Node Set to unschedulable, Then delete the Node All of the Pod, But it won't be deleted piserver Managed Pod
edit	kubectl edit (-f FILENAME | TYPE NAME | TYPE/NAME)[flags]	Edit the properties of the resource object , Online updating
exec	kubectl exec POD [-c CONTAINER] [-i] [-t] [flags] [--COMMAND [args...]]	Execute a command in a container
explain	kubectl explain [--include-extended-apis=true] [--recursive=false] [flags]	A detailed description of resource object properties
expose	kubectl expose (-f FILENAME | TYPE NAME | TYPE/NAME)[--port=port][--protocol=TCP|UDP][--target-port=number-or-name][--name=name][----extenal-ip=external-ip-of-service][--type=type]	There will be one that already exists RC、Service、Deployment or Pod Exposed as a new Service
get	kubectl get (-f FILENAME | TYPE [NAME | /NAME | -l label])[--watch][--sort-by=FIELD][[-o | --output] =OUTPUT_FORMAT][flags]	Displays a summary of one or more resource objects
label	kubectl label (-f FILENAME | TYPE NAME | TYPE/NAME) KEY_1=VAL_1 ...KEY_N=VAL_N [--overwrite][--all][--resource-version=version][flags]	Set or update the resource object labels
logs	kubectl logs POD [-c CONTAINER] [--follow][flags]	Print a container log on the screen
Patch	kubectl patch (-f FILENAME | TYPE NAME | TYPE/NAME) --patch PATCH [flags] kubectl patch (-f FILENAME | TYPE NAME | TYPE/NAME) --patch PATCH [flags]	With merge Form to modify the values of some fields of the resource object
port-forward	kubectl port-forward POD [LOCAL_PORT:] REMOTE_PORT [...[LOCAL_PORT_N:]REMOTE_PORT_N][flags]	Map a port number of this machine to Pod Port number , Usually used for testing
proxy	kubectl proxy [--port=PORT][--www=static-dir][--www-prefix][--api-prefix=prefix][flags]	Map a port number of this machine to apiserver
replace	kubectl replace -f FILENAME [flags]	From the configuration file or stdin Replace resource objects
rolling-update	kubectl rolling-update OLD_CONTROLLER_NAME ([NEW_CONTROLLER_NAME] --image=NEW_CONTAINER_IMAGE | -f NEW_CONTROLLER_SPEC)[flags]	Yes RC Rolling upgrade
run	kubectl run NAME --image=image [--env="key=value"][--port=port][--replicas=replicas][--dry=run=bool][--overrides=inline-json][flags]	Based on a mirror image in Kubenetes Start one on the cluster Deployment
scale	kubectl scale (-f FILENAME | TYPE NAME | TYPE/NAME) --replicas=COUNT [--resource-version=version][--current-replicas=count][flags]	Capacity expansion 、 Let's shrink to one Deployment、ReplicaSet、RC or Job in Pod The number of
set	kubectl set SUBCOMMAND [flags]	Set a specific information of the resource object , At present, only support to modify the image of the container
taint	kubectl taint NODE NAME KEY_1=VAL_1:TAINT_EFFECT_1 ... KEY_N=VAL_N:TAINT_EFFECT_N [flags]	Set up Node Of taint Information , Used to put specific Pod Schedule to a specific Node The operation of , by Alpha Features of the version
uncordon	kubectl uncordon NODE [flags]	take Node Set to schedulable
version	kubectl version [--client][flags]

kubectl parameter list

kubectl The common startup parameters of the command line are as follows ：

Parameter name and value example	explain
–alsologtostderr=false	Set to true Identify that the log is output to the file at the same time as stderr
–as=‘’	Set the user name for this operation
–certificate-authority=‘’	be used for CA Authorized by the cert File path
–client-certificate=‘’	be used for TLS The client certificate file path of
–client-key=‘’	be used for TLS The client of key File path
–cluster=‘’	Set the... To use kubeconfig Medium cluster name
–context=‘’	Set the... To use kubeconfig Medium context name
–insecure-skip-tls-verify=false	Set to true Identity skip TLS Security authentication mode , Will be HTTPS Unsafe connection
–kubeconfig=‘’	kubeconfig Profile path , Include in the configuration file Master Address information and necessary authentication information
–log-backtrace-at=:0	Record the log every time "file： Line number " Print once stack trace
–log-dir=‘’	Log file path
–log-flush-frequency=5s	Set up flush Log file interval
–logtostderr=true	Set to true Output log to stderr, No output to log file
–match-server-version=false	Set to true Indicates that the version number of the client must be consistent with that of the server
–namespace=‘’	Set the location of this operation namespace
–password=‘’	Set up apiserver Of basic authentication Password
-s, --server=‘’	Set up apiserver Of URL Address , The default value is localhost:8080
–stderrthreshold=2	In the threshold Logs above level are output to stderr
–token=‘’	Set access apiserver The safety of the token
–user=‘’	Appoint kubeconfig user name
–username=‘’	Set up apiserver Of basic authentication Username
–v=0	glog The level of logging
–vmodule=	glog Detailed log level based on Module

kubectl Output format

kubectl The command can display the results in a variety of formats , The output is formatted by -o Parameter assignment ：
kubectl [command] [TYPE] [NAME] -o=<output_format>

Output format	explain
-o=custom-columns=<spec>	Output according to the custom column name , Comma separated
-o=custom-columns-file=<filename>	Get the custom column name from the file and output
-o=json	With JSON Format display results
-o=jsonpath=<template>	Output jsonpath Field information defined by an expression
-o=jsonpath-file=<filename>	Output jsonpath Field information defined by an expression , From the file
-o=name	Output only the name of the resource object
-o=wide	Output extra information . about Pod, Will output Pod Where Node name
-o=yaml	With yaml Format display results

Common output formats are as follows

Show Pod For more information ：
kubectl get pod <pod-name> -o wide

With yaml Format display Pod Details of ：
kubectl get pod <pod-name> -o yaml

Display with custom column names Pod Information about ：
kubectl get pod <pod-name> -o=custom-columns=NAME:.metadata.name,RSRC:.metadata.resourceVersion

Custom column name output based on file ：
kubectl get pods <pod-name> -o=custom-columns-file=template.txt

template.txt The contents of the file are ：

NAME							RSRC
metadata.name			metadata.resourceVersion

The output is ：

NAME							RSRC
pod-name					52305

in addition , You can also sort the output results by a certain field , adopt –sort-by Parameter with jsonpath Expression ：
kubectl [command] [TYPE] [NAME] --sort-by=<jsonpath_exp>

for example , Sort by name ：
kubectl get pods --sort-by=.metadata.name

kubectl The operation sample

1. Create resource object

according to yaml Configuration file created at one time service and rc：
kubectl create -f my_service.yaml -f my-rc.yaml

according to directory All under directory .yaml、.yml、.json Create the file definition ：
kubectl create -f directory

2. View resource objects

View all Pod list ：
kubectl get pods

see rc and service list ：
kubectl get rc, service

3. Describe resource objects

Show Node Details of ：
kubectl describe nodes <node-name>

Show Pod Details of ：
kubectl describe pods/<pod-name>

Show by RC Managed Pod Information about ：
kubectl describe pods <rc-name>

4. Delete resource object

be based on pod.yaml Defined name delete Pod：
kubectl delete -f pod.yaml

Delete all containing a label Of Pod and service：
kubectl delete pods, services -l name=<label-name>

Delete all Pod：
kubectl delete pods --all

5. Execute the command of the container

perform Pod Of date command , By default Pod The first container in executes ：
kubectl exec <pod-name> date

Appoint Pod A container in the executes date command ：
kubectl exec <pod-name> -c <container-name> date

adopt bash get Pod Of a container in TTY, Equivalent to login container ：
kubectl exec -ti <pod-name> -c <container-name> /bin/bash

6. View the container's log

See the container output to stdout Log ：
kubectl logs <pod-name>

Track and view container logs , amount to tail -f Results of command ：
kubectl logs -f <pod-name> -c <container-name>