三、kubernetes應用快速入門190625

1、kubernetes應用入門

一、kubectl命令

• Basic Commands

create         Create a resource from a file or from stdin.
  expose         Take a replication controller, service, deployment or pod and expose it as a new Kubernetes Service
  run            Run a particular image on the cluster
  set            Set specific features on objects
  explain        Documentation of resources
  get            Display one or many resources
  edit           Edit a resource on the server
  delete         Delete resources by filenames, stdin, resources and names, or by resources and label selector

• Deploy Commands

rollout        Manage the rollout of a resource
  scale          Set a new size for a Deployment, ReplicaSet, Replication Controller, or Job
  autoscale      Auto-scale a Deployment, ReplicaSet, or ReplicationController

• Cluster Management Commands

certificate    Modify certificate resources.
  cluster-info   Display cluster info
  top            Display Resource (CPU/Memory/Storage) usage.
  cordon         Mark node as unschedulable
  uncordon       Mark node as schedulable
  drain          Drain node in preparation for maintenance
  taint          Update the taints on one or more nodes

• Troubleshooting and Debugging Commands

describe       Show details of a specific resource or group of resources
  logs           Print the logs for a container in a pod
  attach         Attach to a running container
  exec           Execute a command in a container
  port-forward   Forward one or more local ports to a pod
  proxy          Run a proxy to the Kubernetes API server
  cp             Copy files and directories to and from containers.
  auth           Inspect authorization

• Advanced Commands

diff           Diff live version against would-be applied version
  apply          Apply a configuration to a resource by filename or stdin
  patch          Update field(s) of a resource using strategic merge patch
  replace        Replace a resource by filename or stdin
  wait           Experimental: Wait for a specific condition on one or many resources.
  convert        Convert config files between different API versions
  kustomize      Build a kustomization target from a directory or a remote url.

• Settings Commands

label          Update the labels on a resource
  annotate       Update the annotations on a resource
  completion     Output shell completion code for the specified shell (bash or zsh)

• Other Commands

api-resources  Print the supported API resources on the server
  api-versions   Print the supported API versions on the server, in the form of "group/version"
  config         Modify kubeconfig files
  plugin         Provides utilities for interacting with plugins.
  version        Print the client and server version information

二、k8s使用快速入門

• kubectl run和delete：建立一個deployment或者job控制器控制啓動的容器

~]# kubectl run nginx-deploy --image=nginx:1.14 --port=80 --replicas=2
    --port=80：端口暴露
    --replicas=2：副本個數
    --dry-run=true：幹跑一次
~]# kubectl delete pods nginx-deploy-bc9ff65dd-lj9bg  #刪除pods，控制器會自動再起一個，讓副本保持在2個

• kubectl expose：建立service服務，爲pod提供固定訪問端點

~]# kubectl expose deployment nginx-deploy --name nginx-service --port=80 --target-port=80 --protocol=TCP
    deployment nginx-deploy：指定暴露的控制器下的pod
    --name nginx-service：service名稱
    --port=80：service端口
    --target-port=80：後端pod端口
    --protocol=TCP：協議

• kubectl get：獲取資源信息

~]# kubectl get deployment
~]# kubectl get pods
~]# kubectl get pods -o wide  #查看pod運行的詳細信息
~]# kubectl get pods --show-labels  #顯示標籤
~]# kubectl get pods -n kube-system -o wide  #顯示system名稱空間的詳細信息
~]# kubectl get svc  #獲取當前集羣的svc
~]# kubectl get svc -n kube-system -o wide

• kubectl edit：修改編輯資源

~]# kubectl edit svc nginx-service

• kubectl describe：查看資源的詳細信息

~]# kubectl describe svc nginx-service  #查詢svc的詳細信息

• kubectl scale：擴展/縮減副本pod

~]# kubectl scale --replicas=3 deployment nginx-deploy

• kubectl set：灰度升級鏡像版本
• kubectl rollout：回滾

三、使用示例

1. 建立2個提供web的pod

~]# kubectl run myapp --image=dongfeimg/myapp:v1 --replicas=2

1. 建立一個客戶端pod

~]# kubectl run client --image=centos --replicas=1 -it --restart=Never
[root@client /]# curl 10.244.1.3
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
[root@client /]# curl 10.244.1.3/hostname.html
myapp-6fd6445cc6-5p676

1. 爲myapp建立一個service

~]# kubectl expose deployment myapp --name=myapp --port=80

1. 在client測試，service能夠實現輪詢調度

[root@client /]# curl myapp/hostname.html
myapp-6fd6445cc6-2hx5h
[root@client /]# curl myapp/hostname.html
myapp-6fd6445cc6-5p676

1. 將pod擴展至5個副本

~]# kubectl scale --replicas=5 deployment myapp

1. 鏡像升級（灰度）

~]# kubectl set image deployment myapp myapp=dongfeimg/myapp:v2
~]# kubectl rollout status deployment myapp  #查看更新進度

1. 回滾上一版本

~]# kubectl rollout undo deployment myapp

四、補充：配置爲可在集羣外訪問service

~]# kubectl edit svc myapp
type: NodePort
~]# kubectl get svc
myapp           NodePort    10.96.37.191   <none>        80:30804/TCP   17m
在集羣外訪問：http://${NODE_IP}:30804