Introduction to kubernetes resource object and common commands

Namespace

stay kubernetes in , Namespaces are used to isolate resources . For example, configure the dictionary , Internal routing, etc , Each namespace can only use the... Under it .

1. View namespace

kubectl get ns

ns yes namespace Abbreviation .

2. Create a namespace

Create a hello The namespace of .

• Command line mode

kubectl create ns hello

• yaml The way ,hello.yaml

apiVersion: v1
kind: Namespace
metadata:
  name: hello 

kubectl apply -f hello.yaml

3. Delete namespace

• Command line mode

kubectl delete ns hello

• yaml The way

kubectl delete -f hello.yaml

It should be noted that the system default namespace cannot be deleted . Include default. And deleting a namespace will delete all resources deployed in the space , Prudent operation .

Pod

pod Is a set of containers in operation , yes kubernetes The smallest unit applied in .

1. see pod

kubectl get pod -A

By default, this command is to view all pod. If we want to see... Under the specified namespace pod, have access to kubectl get pod -n Space name , Without parameters , View the default namespace .

2. establish pod

Create a name mynginx Of pod, The image used is nginx.

• Command line mode

kubectl run mynginx --image=nginx

[[email protected] ~]# kubectl get pod [mynginx]
NAME      READY   STATUS    RESTARTS   AGE
mynginx   1/1     Running   0          80s
[[email protected] ~]# 

explain ：NAME Express pod name .READY Indicates the number of containers ready and the total number of containers .STATUS According to state .RESTARTS Indicates the number of restarts .AGE Indicates the creation duration .

• yaml The way ,nginx.yaml

apiVersion: v1
kind: Pod
metadata:
  name: mynginx
  namespace: default
spec:
  containers:
  - image: nginx
    name: mynginx

3. Print detailed description

[[email protected] ~]# kubectl describe pod [mynginx]
......
Events:
  Type    Reason     Age    From               Message
  ----    ------     ----   ----               -------
  Normal  Scheduled  4m54s  default-scheduler  Successfully assigned default/mynginx to k8s-worker2
  Normal  Pulling    4m53s  kubelet            Pulling image "nginx"
  Normal  Pulled     3m49s  kubelet            Successfully pulled image "nginx" in 1m4.144467081s
  Normal  Created    3m48s  kubelet            Created container mynginx
  Normal  Started    3m48s  kubelet            Started container mynginx
[[email protected] ~]# 

Mainly look at the event part . Including the information of the assigned node, etc . We found out k8s-worker2 Node created pod, So pass docker ps | grep mynginx The only time to check is worker2 Nodes can be seen .

4. Print detailed log information

[[email protected] ~]# kubectl logs [mynginx]
...
2022/06/27 15:18:45 [notice] 1#1: start worker process 32
2022/06/27 15:18:45 [notice] 1#1: start worker process 33
[[email protected] ~]# 

5. see pod Assigned ip

[[email protected] ~]# kubectl get pod -owide [mynginx]
NAME      READY   STATUS    RESTARTS   AGE    IP              NODE          NOMINATED NODE   READINESS GATES
mynginx   1/1     Running   0          4m6s   192.168.126.8   k8s-worker2   <none>           <none>
[[email protected] ~]# 

Any machine and any application in the cluster can pass Pod The distribution of ip To visit this Pod,curl 192.168.126.8:[80].

6. Get into pod Inside of container

[[email protected] ~]# kubectl exec -it [mynginx] -c [mynginx] -- /bin/bash
[email protected]:/# ls
bin   dev     docker-entrypoint.sh  home  lib64  mnt  proc  run   srv  tmp  var
boot  docker-entrypoint.d  etc    lib   media  opt  root  sbin  sys  usr
[email protected]:/# 

Be careful , If it is multi container pod, We can add parameters -c Container name You can enter the designated container .

6. Delete pod

kubectl delete pod [mynginx]

kubectl delete -f nginx.yml

Key points ：pod yes kubernetes The smallest unit applied in . In the same pod The inner container can be used directly 127.0.0.1: port Mode of access , But be careful , Ports cannot be duplicated .