kubectl-basics

kubectl Basic Operations

Overview

kubectl is the command-line tool for Kubernetes, used to interact with the cluster. This skill covers the most commonly used commands in daily operations.

Cluster Information

# 集群信息
kubectl cluster-info
kubectl version

# 节点信息
kubectl get nodes
kubectl describe node <node-name>

Context Switching

kubectl config get-contexts kubectl config use-context

## 资源查看

### 常用资源
```bash
# Pod
kubectl get pods
kubectl get pods -o wide
kubectl get pods -A                    # 所有命名空间

# Deployment
kubectl get deployments
kubectl get deploy -o yaml

# Service
kubectl get services
kubectl get svc

# 所有资源
kubectl get all
kubectl get all -n <namespace>

Output Formats

kubectl get pods -o wide               # 详细信息
kubectl get pods -o yaml               # YAML 格式
kubectl get pods -o json               # JSON 格式
kubectl get pods -o jsonpath='{.items[*].metadata.name}'

Resource Operations

Create and Delete

# 从文件创建
kubectl apply -f manifest.yaml
kubectl create -f manifest.yaml

# 删除资源
kubectl delete -f manifest.yaml
kubectl delete pod <pod-name>
kubectl delete pod <pod-name> --force --grace-period=0

Edit and Update

# 编辑资源
kubectl edit deployment <name>

# 打补丁
kubectl patch deployment <name> -p '{"spec":{"replicas":3}}'

# 扩缩容
kubectl scale deployment <name> --replicas=5

Pod Debugging

# 查看日志
kubectl logs <pod-name>
kubectl logs <pod-name> -c <container>
kubectl logs <pod-name> -f              # 实时跟踪
kubectl logs <pod-name> --previous      # 上一个容器

# 进入容器
kubectl exec -it <pod-name> -- /bin/bash
kubectl exec -it <pod-name> -c <container> -- sh

# 端口转发
kubectl port-forward <pod-name> 8080:80
kubectl port-forward svc/<service> 8080:80

Common Scenarios

Scenario 1: Quickly Troubleshoot Pod Issues

# 1. 查看 Pod 状态
kubectl get pod <name> -o wide

# 2. 查看事件
kubectl describe pod <name> | grep -A 20 Events

# 3. 查看日志
kubectl logs <name> --tail=100

Scenario 2: Rolling Update

# 更新镜像
kubectl set image deployment/<name> container=image:tag

# 查看更新状态
kubectl rollout status deployment/<name>

# 回滚
kubectl rollout undo deployment/<name>
kubectl rollout history deployment/<name>

Shortcut Aliases

# 推荐添加到 ~/.bashrc 或 ~/.zshrc
alias k='kubectl'
alias kgp='kubectl get pods'
alias kgs='kubectl get svc'
alias kgd='kubectl get deploy'
alias kd='kubectl describe'
alias kl='kubectl logs'
alias ke='kubectl exec -it'

Troubleshooting

Status	Possible Cause	Troubleshooting Command
Pending	Insufficient resources/scheduling issue	kubectl describe pod
CrashLoopBackOff	Application crash	kubectl logs --previous
ImagePullBackOff	Image pull failure	kubectl describe pod
OOMKilled	Memory limit exceeded	Check resources.limits