MDYH

05 Kubernetes

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Kubernetes基础

Kubernetes概述

核心概念

概念说明
Pod最小部署单元，一个或多个容器
Node工作节点，运行Pod的机器
Cluster集群，由Master和Worker节点组成
Namespace资源隔离的逻辑分区
Deployment管理Pod副本和更新策略
Service提供稳定的访问入口
ConfigMap配置数据存储
Secret敏感数据存储
Volume存储卷
IngressHTTP路由规则

架构组件

┌─────────────────────────────────────────────────────────┐
│                     Master Node                          │
│  ┌─────────┐  ┌─────────┐  ┌─────────┐  ┌─────────┐    │
│  │ API     │  │Scheduler│  │Controller│ │  etcd   │    │
│  │ Server  │  │         │  │ Manager  │ │         │    │
│  └─────────┘  └─────────┘  └─────────┘  └─────────┘    │
└─────────────────────────────────────────────────────────┘
                          │
        ┌─────────────────┼─────────────────┐
        ▼                 ▼                 ▼
┌───────────────┐ ┌───────────────┐ ┌───────────────┐
│  Worker Node  │ │  Worker Node  │ │  Worker Node  │
│ ┌───────────┐ │ │ ┌───────────┐ │ │ ┌───────────┐ │
│ │ kubelet   │ │ │ │ kubelet   │ │ │ │ kubelet   │ │
│ │ kube-proxy│ │ │ │ kube-proxy│ │ │ │ kube-proxy│ │
│ │ runtime   │ │ │ │ runtime   │ │ │ │ runtime   │ │
│ └───────────┘ │ │ └───────────┘ │ │ └───────────┘ │
│   Pods...     │ │   Pods...     │ │   Pods...     │
└───────────────┘ └───────────────┘ └───────────────┘

kubectl命令

基本命令

# 集群信息
kubectl cluster-info
kubectl version
kubectl get nodes
kubectl describe node node-name
 
# 资源查看
kubectl get pods                      # 查看Pod
kubectl get pods -n namespace         # 指定命名空间
kubectl get pods -A                   # 所有命名空间
kubectl get pods -o wide              # 详细信息
kubectl get deployments
kubectl get services
kubectl get all                       # 所有资源
 
# 详细信息
kubectl describe pod pod-name
kubectl describe deployment deploy-name
 
# 日志查看
kubectl logs pod-name
kubectl logs -f pod-name              # 实时跟踪
kubectl logs pod-name -c container    # 指定容器
kubectl logs --previous pod-name      # 上一个容器日志
 
# 进入容器
kubectl exec -it pod-name -- bash
kubectl exec -it pod-name -c container -- bash
 
# 端口转发
kubectl port-forward pod-name 8080:80
kubectl port-forward service/svc-name 8080:80

资源创建与删除

# 创建资源
kubectl apply -f deployment.yaml
kubectl create deployment nginx --image=nginx
 
# 删除资源
kubectl delete -f deployment.yaml
kubectl delete pod pod-name
kubectl delete deployment deploy-name
kubectl delete all --all              # 删除所有资源
 
# 编辑资源
kubectl edit deployment deploy-name
 
# 扩缩容
kubectl scale deployment nginx --replicas=3
kubectl autoscale deployment nginx --min=2 --max=10 --cpu-percent=80

配置管理

# ConfigMap
kubectl create configmap my-config --from-literal=key1=value1
kubectl create configmap my-config --from-file=config.txt
kubectl get configmap
kubectl describe configmap my-config
 
# Secret
kubectl create secret generic my-secret --from-literal=password=secret123
kubectl create secret tls tls-secret --cert=path/to/cert --key=path/to/key
kubectl get secrets
kubectl describe secret my-secret
 
# 解码Secret
kubectl get secret my-secret -o jsonpath='{.data.password}' | base64 -d

资源定义文件

Pod

# pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: my-app
  labels:
    app: my-app
    tier: frontend
spec:
  containers:
  - name: my-app
    image: nginx:latest
    ports:
    - containerPort: 80
    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"
    livenessProbe:
      httpGet:
        path: /health
        port: 80
      initialDelaySeconds: 30
      periodSeconds: 10
    readinessProbe:
      httpGet:
        path: /ready
        port: 80
      initialDelaySeconds: 5
      periodSeconds: 5
    env:
    - name: ENV_VAR
      value: "value"
    volumeMounts:
    - name: data
      mountPath: /data
  volumes:
  - name: data
    emptyDir: {}

Deployment

# deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.24
        ports:
        - containerPort: 80
        resources:
          requests:
            memory: "128Mi"
            cpu: "100m"
          limits:
            memory: "256Mi"
            cpu: "200m"
        volumeMounts:
        - name: config
          mountPath: /etc/nginx/nginx.conf
          subPath: nginx.conf
      volumes:
      - name: config
        configMap:
          name: nginx-config

Service

# service.yaml
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  type: ClusterIP                    # ClusterIP, NodePort, LoadBalancer
  selector:
    app: nginx
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP
 
---
# NodePort Service
apiVersion: v1
kind: Service
metadata:
  name: nginx-nodeport
spec:
  type: NodePort
  selector:
    app: nginx
  ports:
  - port: 80
    targetPort: 80
    nodePort: 30080

Ingress

# ingress.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: nginx-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  ingressClassName: nginx
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: nginx-service
            port:
              number: 80
  tls:
  - hosts:
    - example.com
    secretName: tls-secret

ConfigMap与Secret

# configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  database_url: "mysql://localhost:3306/mydb"
  cache_ttl: "3600"
  config.json: |
    {
      "key": "value",
      "nested": {
        "key": "value"
      }
    }
 
---
# secret.yaml
apiVersion: v1
kind: Secret
metadata:
  name: app-secret
type: Opaque
data:
  username: YWRtaW4=                    # base64编码
  password: cGFzc3dvcmQxMjM=
stringData:                             # 自动编码
  api-key: "secret-api-key"

PersistentVolume

# pv.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-data
spec:
  capacity:
    storage: 10Gi
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: standard
  hostPath:
    path: /data/pv
 
---
# pvc.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-data
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: standard
 
---
# 在Pod中使用
apiVersion: v1
kind: Pod
metadata:
  name: app-with-pvc
spec:
  containers:
  - name: app
    image: nginx
    volumeMounts:
    - name: data
      mountPath: /data
  volumes:
  - name: data
    persistentVolumeClaim:
      claimName: pvc-data

常用运维操作

滚动更新

# 更新镜像
kubectl set image deployment/nginx nginx=nginx:1.25
 
# 查看更新状态
kubectl rollout status deployment/nginx
 
# 查看更新历史
kubectl rollout history deployment/nginx
 
# 回滚
kubectl rollout undo deployment/nginx
kubectl rollout undo deployment/nginx --to-revision=2
 
# 暂停和恢复
kubectl rollout pause deployment/nginx
kubectl rollout resume deployment/nginx

故障排查

# Pod状态异常
kubectl describe pod pod-name         # 查看事件
kubectl logs pod-name                 # 查看日志
kubectl get events --sort-by=.metadata.creationTimestamp
 
# 节点问题
kubectl describe node node-name
kubectl get nodes -o wide
kubectl cordon node-name              # 标记节点不可调度
kubectl drain node-name               # 驱逐节点上的Pod
kubectl uncordon node-name            # 恢复调度
 
# 资源使用
kubectl top nodes
kubectl top pods

调试技巧

# 创建临时调试Pod
kubectl run debug --rm -it --image=busybox -- sh
kubectl run debug --rm -it --image=nicolaka/netshoot -- bash
 
# 复制Pod进行调试
kubectl debug pod-name -it --copy-to=debug-pod --image=busybox
 
# 查看资源定义
kubectl get pod pod-name -o yaml
kubectl get pod pod-name -o json

Helm包管理

基本命令

# 添加仓库
helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update
 
# 搜索Chart
helm search repo nginx
helm show values bitnami/nginx        # 查看默认值
 
# 安装
helm install my-nginx bitnami/nginx
helm install my-nginx bitnami/nginx -f values.yaml
helm install my-nginx bitnami/nginx --set service.type=NodePort
 
# 升级
helm upgrade my-nginx bitnami/nginx
helm upgrade my-nginx bitnami/nginx --set replicaCount=3
 
# 卸载
helm uninstall my-nginx
 
# 查看已安装
helm list
helm status my-nginx

💡 Kubernetes建议:

  • 使用声明式配置（YAML文件）
  • 设置合理的资源限制
  • 配置健康检查探针
  • 使用Namespace隔离环境

🔗 相关笔记: 10.01_Docker基础 09.01_Web服务部署 11.01_Shell自动化脚本

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