Master Essential k8s Pod Commands and Real-World Scenarios

1. k8s-pod common management commands

Create Pod:

kubectl apply -f pod.yaml
kubectl run nginx --image=nginx

View Pods:

kubectl get pods
kubectl describe pod <PodName>

View logs:

kubectl logs <PodName> [-c CONTAINER]
kubectl logs <PodName> [-c CONTAINER] -f

Enter container terminal: kubectl exec <PodName> [-c CONTAINER] --bash Delete Pod: kubectl delete <PodName> Export Pod YAML configuration:

# Example output of kubectl get pods
NAME                     READY   STATUS    RESTARTS   AGE
nginx-6799fc88d8-s5wvx   1/1     Running   1          40h
...

2. k8s-pod case

2.1 Implement network sharing

2.1.1 Export configuration file and write case

# Write web-pod.yaml for testing
apiVersion: v1
kind: Pod
metadata:
  labels:
    app: pod-test
  name: pod-net-test
  namespace: default
spec:
  containers:
  - image: busybox
    imagePullPolicy: Always
    name: pod-test
    command: ["/bin/sh"]
    args:
      - "-c"
      - "sleep 3000000"
  - image: nginx
    name: web

2.1.2 Apply configuration file

# kubectl apply -f web-pod.yaml
pod/pod-net-test created

2.1.3 Monitor pod startup

# kubectl get pods
NAME                     READY   STATUS            RESTARTS   AGE
nginx-6799fc88d8-s5wvx   1/1     Running           1          41h
pod-net-test             0/2     ContainerCreating 0          19s
...
# kubectl get pods -w   # watch continuously

Note: using -w watches pod status continuously.

2.1.4 Enter pod

# kubectl exec -it pods/pod-net-test -c pod-test -- /bin/sh
Defaulting container name to pod-test.
/ # ifconfig
eth0      Link encap:Ethernet  HWaddr 5A:C1:FA:25:85:C0
          inet addr:10.244.169.139  Bcast:10.244.169.139  Mask:255.255.255.255
...
/ # netstat -lntup
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      -

exec: command to enter container

-it: allocate a pseudo‑terminal

pod-net-test: pod name

-c pod-test: specify container

-- /bin/sh: shell to use

2.1.5 Verify file inside nginx

# kubectl exec -it pod-net-test -c web -- /bin/bash
root@pod-net-test:/# cd /usr/share/nginx/html/
root@pod-net-test:/usr/share/nginx/html# echo 'pod-test' >index.html
# kubectl exec -it pod-net-test -c pod-test -- /bin/sh
/ # wget http://127.0.0.1:80
... saved 'index.html'
/ # cat index.html
pod-test

Summary:

We modified index.html in the nginx container to verify network sharing.

When entering a container, always use the -c flag to specify which container.

2.2 Implement shared storage

2.2.1 Write pod-volume-test.yaml

apiVersion: v1
kind: Pod
metadata:
  labels:
    app: test
  name: pod-volume-test
  namespace: default
spec:
  containers:
  - image: busybox
    imagePullPolicy: Always
    name: test
    command: ["/bin/sh"]
    args:
      - "-c"
      - "sleep 3000000"
    volumeMounts:
    - name: log
      mountPath: /data
  - image: nginx
    name: web
    volumeMounts:
    - name: log
      mountPath: /data
  volumes:
  - name: log
    emptyDir: {}

2.2.2 Create shared directory

# mkdir -p /data

2.2.3 Start service

# kubectl apply -f pod-volume-test.yaml
pod/pod-volume-test created

2.2.4 Verify service startup

# kubectl get pods
NAME                     READY   STATUS    RESTARTS   AGE
nginx-6799fc88d8-tfgfr   1/1     Running   0          30m
pod-volume-test          2/2     Running   0          2m37s
...

2.2.5 Verify data volume is shared

# kubectl exec -it pod-volume-test -c web -- /bin/bash
root@pod-volume-test:/# cd /data
root@pod-volume-test:/data# echo 'pod volume test' >index.html
root@pod-volume-test:/data# ls
index.html
# kubectl exec -it pod-volume-test -c test -- /bin/sh
/data # cat index.html
pod volume test

2.2.6 View logs

# kubectl logs pod-volume-test -c web -f
/docker-entrypoint.sh: Configuration complete; ready for start up
... (nginx access log) ...

3. k8s-pod field details

# Full pod definition in YAML
apiVersion: v1               # required, e.g., v1
kind: Pod                     # required, Pod
metadata:
  name: string               # required, pod name
  namespace: string          # required, namespace
  labels:                    # custom labels
    - name: string
  annotations:               # custom annotations
    - name: string
spec:
  containers:                # list of containers
    - name: string           # container name
      image: string          # container image
      imagePullPolicy: [Always|Never|IfNotPresent]
      command: [string]
      args: [string]
      workingDir: string
      volumeMounts:
        - name: string
          mountPath: string
          readOnly: boolean
      ports:
        - name: string
          containerPort: int
          hostPort: int
          protocol: string
      env:
        - name: string
          value: string
      resources:
        limits:
          cpu: string
          memory: string
        requests:
          cpu: string
          memory: string
      livenessProbe:
        exec:
          command: [string]
        httpGet:
          path: string
          port: number
          host: string
          scheme: string
          httpHeaders:
            - name: string
              value: string
        tcpSocket:
          port: number
        initialDelaySeconds: 0
        timeoutSeconds: 0
        periodSeconds: 0
        successThreshold: 0
        failureThreshold: 0
      securityContext:
        privileged: false
  restartPolicy: [Always|Never|OnFailure]
  nodeSelector: object
  imagePullSecrets:
    - name: string
  hostNetwork: false
  volumes:
    - name: string
      emptyDir: {}
      hostPath: string
      secret:
        secretName: string
        items:
          - key: string
            path: string
      configMap:
        name: string
        items:
          - key: string
            path: string