[kubernetes guide ④] pod quick start

Pod yes kubernetes The smallest unit for cluster management , The program must be deployed in a container to run , And the container must exist in Pod in .

Pod It can be considered as the encapsulation of the container , One Pod There can be one or more containers in the .

kubernetes After cluster startup , Each component in the cluster is also based on Pod Way to run . You can view it through the following command ：

[[email protected] ~]# kubectl get pod -n kube-system
NAMESPACE     NAME                             READY   STATUS    RESTARTS   AGE
kube-system   coredns-6955765f44-68g6v         1/1     Running   0          2d1h
kube-system   coredns-6955765f44-cs5r8         1/1     Running   0          2d1h
kube-system   etcd-master                      1/1     Running   0          2d1h
kube-system   kube-apiserver-master            1/1     Running   0          2d1h
kube-system   kube-controller-manager-master   1/1     Running   0          2d1h
kube-system   kube-flannel-ds-amd64-47r25      1/1     Running   0          2d1h
kube-system   kube-flannel-ds-amd64-ls5lh      1/1     Running   0          2d1h
kube-system   kube-proxy-685tk                 1/1     Running   0          2d1h
kube-system   kube-proxy-87spt                 1/1     Running   0          2d1h
kube-system   kube-scheduler-master            1/1     Running   0          2d1h

Create and run

kubernetes No separate operation is provided Pod The order of , It's all through Pod Controller

#  Command format ： kubectl run (pod Controller name ) [ Parameters ]
# --image  Appoint Pod Mirror image 
# --port  Designated port 
# --namespace  Appoint namespace
[[email protected] ~]# kubectl run nginx --image=nginx:latest --port=80 --namespace dev 
deployment.apps/nginx created

see pod Information

#  see Pod essential information 
[[email protected] ~]# kubectl get pods -n dev
NAME    READY   STATUS    RESTARTS   AGE
nginx   1/1     Running   0          43s

#  see Pod Details of 
[[email protected] ~]# kubectl describe pod nginx -n dev
Name:         nginx
Namespace:    dev
Priority:     0
Node:         node1/192.168.5.4
Start Time:   Wed, 08 May 2021 09:29:24 +0800
Labels:       pod-template-hash=5ff7956ff6
              run=nginx
Annotations:  <none>
Status:       Running
IP:           10.244.1.23
IPs:
  IP:           10.244.1.23
Controlled By:  ReplicaSet/nginx
Containers:
  nginx:
    Container ID:   docker://4c62b8c0648d2512380f4ffa5da2c99d16e05634979973449c98e9b829f6253c
    Image:          nginx:latest
    Image ID:       docker-pullable://[email protected]:485b610fefec7ff6c463ced9623314a04ed67e3945b9c08d7e53a47f6d108dc7
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Wed, 08 May 2021 09:30:01 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-hwvvw (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-hwvvw:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-hwvvw
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type    Reason     Age        From               Message
  ----    ------     ----       ----               -------
  Normal  Scheduled  <unknown>  default-scheduler  Successfully assigned dev/nginx-5ff7956ff6-fg2db to node1
  Normal  Pulling    4m11s      kubelet, node1     Pulling image "nginx:latest"
  Normal  Pulled     3m36s      kubelet, node1     Successfully pulled image "nginx:latest"
  Normal  Created    3m36s      kubelet, node1     Created container nginx
  Normal  Started    3m36s      kubelet, node1     Started container nginx

visit Pod

#  obtain podIP
[[email protected] ~]# kubectl get pods -n dev -o wide
NAME    READY   STATUS    RESTARTS   AGE    IP             NODE    ... 
nginx   1/1     Running   0          190s   10.244.1.23   node1   ...

# visit POD
[[email protected] ~]# curl http://10.244.1.23:80
<!DOCTYPE html>
<html>
<head>
	<title>Welcome to nginx!</title>
</head>
<body>
	<p><em>Thank you for using nginx.</em></p>
</body>
</html>

Delete the specified Pod

#  Delete the specified Pod
[[email protected] ~]# kubectl delete pod nginx -n dev
pod "nginx" deleted

#  here , Show delete Pod success , But check again , Discovery has created a new  
[[email protected] ~]# kubectl get pods -n dev
NAME    READY   STATUS    RESTARTS   AGE
nginx   1/1     Running   0          21s

#  This is because of the current Pod By Pod Created by controller , The controller will monitor Pod condition , Once found Pod Death , Will be rebuilt immediately 
#  At this point, you want to delete Pod, Must delete Pod controller 

#  Let's check the current namespace Under the Pod controller 
[[email protected] ~]# kubectl get deploy -n dev
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
nginx   1/1     1            1           9m7s

#  Next , Delete this PodPod controller 
[[email protected] ~]# kubectl delete deploy nginx -n dev
deployment.apps "nginx" deleted

#  Wait a moment , The query again Pod, Find out Pod Been deleted 
[[email protected] ~]# kubectl get pods -n dev
No resources found in dev namespace.

Configuration operation

Create a pod-nginx.yaml, The contents are as follows ：

apiVersion: v1
kind: Pod
metadata:
  name: nginx
  namespace: dev
spec:
  containers:
  - image: nginx:latest
    name: pod
    ports:
    - name: nginx-port
      containerPort: 80
      protocol: TCP

Then you can execute the corresponding create and delete commands ：

establish ：kubectl create -f pod-nginx.yaml

Delete ：kubectl delete -f pod-nginx.yaml

---

《 Core technology series column summary 》

• 《Java Is the core technology 》
• 《 Middleware core technology 》
• 《 Core technology of microservice 》
• 《 Cloud native core technology 》
• 《 Common business implementation set 》
• 《 Let's go to Dachang series 》
• 《 Open source project o s s a》

need Interview questions of Dachang 、 resume template 、 e-book 、 Learning materials Etc 【 official account 】 reply 「 1024 」 that will do .