Kubernetes cluster management (2)

Introduction to kubernetes resource management

In kubernetes, all content is abstractly called resources, and users need to manage k8s by operating resources

The essence of kubernetes is a cluster system. Users can deploy various services in the cluster. The so-called deployment is to run containers one by one in the k8s cluster, and run the executed program in the container.

The smallest management unit of kubernetes is a pod rather than a container, so the container can only be placed in the pod, and k8s generally does not directly manage the pod, but manages the pod through the pod controller

Dod can provide services, so it is necessary to consider how to access the services in the pod. Kubernetes provides two resources, service and ingress, to use this function. When pod data needs to be persisted, k8s also provides a variety of storage systems

Yaml language introduction

kubernetes中资源配置文件都是基于 YAML 语言编写，JSON 相对使用较少因为该文件无法注释

Yaml information:​ ​A brief introduction to the syntax of Yaml_Three Tigers' Technical Blog_51CTO Blog

Yaml conversion Json tool: http://json2yaml.com/convert-yaml-to-json

k8s resource management method

Imperative object management: directly use commands to operate on resources

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

Imperative object configuration: specify configuration files through commands to operate resources

kubectl create -f nginx-pod.yaml

Declarative object configuration: operate resources through apply commands and configuration files, which is equivalent to updating

kubectl apply -f nginx-pod.yaml

type	operation object	Applicable environment	advantage	shortcoming
imperative object management	a resource	test	Simple	Can only operate active objects, cannot audit, track
Imperative object configuration	a file	Production	audit, track	When the project is large, there are too many configuration files and the operation is complicated
Declarative object configuration	entire directory	Production	Support directory operations	Difficult to debug in unexpected situations

kubectl command parameters

Use the kubectl command to manage various resource objects in the cluster

kubectl command syntax:

kubectl [command] itype] [name] [flags]

command: what operation to perform on the resource, such as create, delete, get

type: Specifies the resource type, such as pod, deployment, service

name: the name of the specified resource **flags: * specifies additional optional parameters

kubectl common commands

# 查看所有 pod 资源
kubectl get pod
# 查看 pod 的 yaml 文件
kubectl get pod podname -o yaml
# 查看 pod 的 json 文件
kubectl get pod podname -o json
# 查看 pod 详细信息
kubectl get pod podname -o wide
查看所有的资源类型
kubectl api-resources

kubectl basic command parameters

Order	contain
create	create a resource
edit	edit a resource
get	View a resource information
patch	update a resource
delete	delete a resource
explain	Display resource documents

kubectl run and debug related command parameters

Order	meaning
run	run a specified image
expose	Expose resource as service
describe	View verbose output for resources
logs	View the logs of the container in the pod
attach	into the running container
exec	into the container
cp	Copy files inside and outside pods
rollout	Manage the release of resources
scale	Scale up or down the number of pods
autoscale	The number of automatic jump pods

kubectl advanced command parameters

Order	meaning
apply	Update resource configuration
label	Update labels on resources

kubectl other commands

Order	meaning
cluster-info	display cluster information
version	show cluster version

cluster management

Resource Name	abbreviation	resource role
node	no	cluster components
namespace	ns	isolate pods

pod management

Resource Name	abbreviation	resource role
replicationcontrollers	rc	Controlling Pod Resources
replicasets	rs	Controlling Pod Resources
deployment	deploy	Controlling Pod Resources
daemonsets	ds	Controlling Pod Resources
jobs		Controlling Pod Resources
cronjobs	cj	Controlling Pod Resources
horizontalpodautoscalers	hpa	Controlling Pod Resources
statefulsets	sts	Controlling Pod Resources

service discovery

Resource Name	abbreviation	resource role
services	svc	Unified pod external interface
ingress	ing	Unified pod external interface

storage management

Resource Name	abbreviation	resource role
volumeattachments		storage
persistentvolumes	pv	storage
persistentvolumeclaims	pvc	storage

resource allocation

Resource Name	abbreviation	resource role
configmaps	cm	configuration
secrets		configuration

Summarize