[cloud native | learn kubernetes from scratch] III. kubernetes cluster management tool kubectl

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summary

kubectl yes Kubernetes Command line tools for clustering , adopt kubectl Be able to manage the cluster itself , And can install and deploy container applications on the cluster .

Command format

The command format is as follows

kubectl [command] [type] [name] [flags]

Parameters

• command： Specifies the action to be performed on the resource , for example create、get、describe、delete

• type： Specify the resource type , Resource types are case sensitive , Developers can use the singular number , The plural , Abbreviated form specifies .

• name： Specify the name of the resource , Names are also case sensitive , If you omit the name , All resources will be displayed .

• flags： Specify additional optional parameters , For example, you can use -s perhaps -server Parameter assignment Kubernetes API server The address and port of

for example ：

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

Common command

kubectl help For more information

adopt help command , Can get help information

#  obtain kubectl The order of 
kubectl --help

#  Get the introduction and use of a command 
kubectl get --help

#  View the current status 
kubectl get cs

#  View all pod
kubectl get pod 

#  View a certain pod
kubectl get pod pod_name

#  View a certain pod, With yaml Format display results 
kubectl get pod pod_name -o yaml

Basic commands

Common basic commands

command	Introduce
create	Create resources by filename or standard input
expose	Expose a resource as a new Service
run	Run a specified image in the cluster
set	Set specific functions on objects
get	Show one or more resources
explain	Show document references
edit	Use the default editor to edit a resource
delete	By file name , The standard input , Resource name or tag to delete the resource
apply	Apply configuration to resources by filename or standard input
patch	Patch modification 、 Update resources
replace	Replace a resource with a filename or standard input
convert	Different API Convert configuration files between versions
label	Update the label on the resource
annotate	Update comments on resources
completion	Used to implement kubectl The tool automatically completes
api-versions	Print supported API edition
config	modify kubeconfig file （ Used to access the API, For example, configure authentication information ）
help	All command help
plugin	Run a command line plug-in
version	Print client and service version information

Deployment command

command	Introduce
rollout	Manage the release of resources
rolling-update	Scroll through the updates for a given replication controller
scale	Expand or shrink Pod Number ,Deployment、ReplicaSet、RC or Job
autoscale	Create an automatic selection to expand or shrink and set Pod Number

Cluster management commands

command	Introduce
certificate	Modify certificate resources
cluster-info	Display cluster information
top	Show resources (CPU/M)
cordon	The tag node is not schedulable
uncordon	Marker nodes can be scheduled
drain	Applications on eviction nodes , Prepare for offline maintenance
taint	Modify node taint Mark

Fault and debug commands

command	Introduce
describe	Show details of a specific resource or resource group
logs	In a Pod Print a container log , If Pod There is only one container , The container name is optional
attach	Attach to a running container
exec	Execute command to container
port-forward	Forward one or more
proxy	Run one proxy To Kubernetes API Server
cp	Copy files or directories into containers
auth	Check authorization

Currently commonly used commands

#  Create a nginx Mirror image 
kubectl create deployment nginx --image=nginx

#  External exposure port 
kubectl expose deployment nginx --port=80 --type=NodePort

#  See the resources 
kubectl get pod

#  View details ip, Port, etc .
kubectl get svc

demonstration

Create a namespace

[[email protected] ~]# kubectl create namespace paopao
namespace/paopao created

obtain namespace

[[email protected] ~]# kubectl get ns
NAME              STATUS   AGE
default           Active   7d23h
kube-node-lease   Active   7d23h
kube-public       Active   7d23h
kube-system       Active   7d23h
paopao            Active   22s

Here it is namespace Create and run a nginx Of Pod

[[email protected] ~]# kubectl run pod --image=nginx:latest -n paopao
pod/pod created

See the newly created pod

[[email protected] ~]# kubectl get pod -n paopao
NAME   READY   STATUS    RESTARTS   AGE
pod    1/1     Running   0          3m14s

Delete specified namespace

[[email protected] ~]# kubectl delete ns dev
namespace "dev" deleted

establish / Update resources Configure with declarative objects kubectl apply -f XXX.yaml

Delete resources Use command object configuration kubectl delete -f XXX.yaml

Query resources Use imperative object management kubectl get(describe) Resource name

Resource Management

Imperative object management ： Directly use commands to operate kubernetes resources , Direct action object , Suitable for testing , Relatively simple , The disadvantage is that you can only manipulate active objects , Unable to audit trail .

kubectl run nginx-pod --image=nginx --port=80

Imperative object configuration ： Operate through command configuration and configuration file kubernetes resources , Direct operation of documents , Suitable for development , Can audit and track , But if the project is too big , There will be many configuration files , Operation trouble .

kubectl create -f nginx-pod.yaml
kubectl patch -f nginx-pod.yaml

Declarative object configuration ： adopt apply Commands and configuration files to operate kubernetes resources , Direct operation directory , Suitable for development , Support directory operation , But it's not easy to debug .

kubectl apply -f nginx-pod.yaml

The resource type

kubernetes All the content in is abstracted as resources , You can check it with the following command :

kubectl api-resources

At the end

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