First acquaintance of Kubernetes (K8s): detailed use of the kubectl command

I. Kubectl Usage Overview

kubectl command line syntax is as follows:

kubectl [command] [type] [name] [flags] Parameter description: command: Subcommand, command used to manage and operate Kubernetes cluster resource objects. For example: create, delete, describe, get, apply, etc. type: The type of resource object, case-sensitive, can be expressed in singular, plural, or abbreviated form. kubectl get pod pod1 #singular kubectl get pods pod1 #plural form kubectl get po pod1 #Abbreviated form name: The name of the resource object, case-sensitive, if no name is specified, the system returns a list of all objects belonging to type. flags: Optional parameters to the kubectl subcommand, such as using "-s" to specify the apiserver URL address instead of the default.

Table 1: Resource object types that kubectl can manipulate

Name abbreviation of resource object clustersgroupentstatusescsconfigurmapscmdaemonsetsdsdeploymentsdeploymentpointsepeventsevizontalpodautoscalershpaingressesingJobslimitrangeslimitsnodesnonamespacesnsnetworkpoliciesstatefulsetspersistentvolumeclaimspvcpersistentvolumespopodsecuritypoliciessppodtemplatesreplicasetsrsreplicationcontrolersrccronjobsecretsserviceaccountsservicesvcstorageclassesscthirdpartyresources II, kubectl subcommand

Kuberctl subcommands are very rich, including resource object creation, deletion, view, modify, configure, run and so on.

Table 2: Kubectl Subcommand Syntax

III. Kubectl parameter

Table 3: Kubectl Command Line Common Startup Parameters

Each subcommand (e.g. create, delete, get, etc.) also has a specific flags parameter, which can be viewed with kubectl [command] --help.

IV. Kubectl output format

The kubectl command can display results in a variety of formats, the output format specified by the-o parameter:

kubectl [command] [TYPE] [NAME] -o=

Table 4: Output format of kubectl command

Examples of common output formats are as follows:

(1) Display more information about the Pod

kubectl get pod -o wide

(2) Display Pod details in yaml format

kubectl get pod -o yaml

(3) Display Pod information with custom column names

kubectl get pod -o=custom-columns=NAME:.metadata.name,RSRC:.metadata.resourceVersion

(4) File-based custom column name output

kubectl get pods -o=custom-columns-file= template.txttemplate.txt The contents of the file are: NAME RSRCmetadata.name metadata.resourceVersion Output: NAME RSRCPod-name 52305

Alternatively, you can sort the output by a field, specified as a jsonpath expression with the--sort-by parameter:

kubectl [command] [TYPE] [NAME] --sort-by=

For example, sort by name

kubectl get pods --sort-by=.metadata.name V. kubectl operation example

1. Create service and rc at one time according to yaml configuration file

kubectl create -f my-service.yaml -f my-rc.yaml

2. Create according to the definitions of all.yaml,.yml and.json files in the directory

kubectl create -f

3. View a list of all pods

kubectl get pods

4. View rc and service list

kubectl get rc,service

5. Display node details

kubectl describe nodes

6. Display Pod Details

kubectl describe pods/

7. Display Pod information managed by RC

kubectl describe pods

Delete pods defined based on the pod.yaml file

kubectl delete -f pod.yaml

Delete all Pods and Services that contain a label

kubectl delete pods,services -l name=

Delete all pods

kubectl delete pods --all

11. Execute the date command in the pod container. By default, the first container in the Pod is used.

kubectl exec date

12. Specify a container in the Pod to execute the date command

kubectl exec -c date

13. Log in to a container in Pod as bash

kubectl exec -it -c /bin/bash

14. View the log of container output to stdout

kubectl logs

15. Track and view the log of the container, equivalent to the result of the tail -f command

kubectl logs -f -c