云原生部署（六）：K8s 核心概念——Pod、Deployment、Service、ConfigMap 与 Secret

apiVersion: v1
kind: Pod
metadata:
  name: myapp-pod
  labels:
    app: myapp
    version: v1
spec:
  containers:
  - name: myapp
    image: harbor.yourcompany.com/backend/myapp:v1.0
    ports:
    - containerPort: 8080
    resources:
      requests:
        memory: "256Mi"
        cpu: "250m"
      limits:
        memory: "512Mi"
        cpu: "500m"

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deployment
  labels:
    app: myapp
spec:
  replicas: 3                          # 期望的副本数
  selector:
    matchLabels:
      app: myapp                       # 选择器：管理带 app=myapp 标签的 Pod
  template:                            # Pod 模板
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: harbor.yourcompany.com/backend/myapp:v1.0
        ports:
        - containerPort: 8080
        resources:
          requests:
            memory: "256Mi"
            cpu: "250m"
          limits:
            memory: "512Mi"
            cpu: "500m"

# Pod 的标签
labels:
  app: myapp
  version: v1
  env: staging

# Selector 可以选择
selector:
  matchLabels:
    app: myapp
  # 或更复杂的：
  matchExpressions:
    - {key: version, operator: In, values: [v1, v2]}

apiVersion: v1
kind: Service
metadata:
  name: myapp-service
spec:
  type: ClusterIP          # 只在集群内可访问
  selector:
    app: myapp             # 选择后端 Pod
  ports:
  - port: 80               # Service 的端口
    targetPort: 8080       # 后端 Pod 的端口

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  # 简单键值对
  app.env: "production"
  app.log.level: "INFO"
  # 多行配置文件（注意 | 表示保留换行的 YAML 语法）
  nginx.conf: |
    server {
        listen 80;
        server_name localhost;
        location / {
            root /usr/share/nginx/html;
            index index.html;
        }
    }

apiVersion: v1
kind: Pod
metadata:
  name: configmap-demo
spec:
  containers:
  - name: app
    image: myapp:v1
    # 方式一：作为环境变量
    env:
    - name: APP_ENV
      valueFrom:
        configMapKeyRef:
          name: app-config
          key: app.env
    - name: LOG_LEVEL
      valueFrom:
        configMapKeyRef:
          name: app-config
          key: app.log.level
    # 一次性注入所有键值对（键名作为环境变量名）
    envFrom:
    - configMapRef:
        name: app-config
    # 方式二：作为文件挂载
    volumeMounts:
    - name: config-volume
      mountPath: /etc/config
  volumes:
  - name: config-volume
    configMap:
      name: app-config

apiVersion: v1
kind: Secret
metadata:
  name: db-secret
type: Opaque          # 通用类型，也可以是 kubernetes.io/tls 等
data:
  # 注意：这里的值必须是 base64 编码后的
  username: YWRtaW4=          # admin
  password: UDNzc3cwcmQ=      # 实际生产中不要用弱密码 :)
stringData:                   # stringData 字段会自动做 base64 编码，更方便
  database: myapp-db

apiVersion: v1
kind: Pod
metadata:
  name: secret-demo
spec:
  containers:
  - name: app
    image: myapp:v1
    env:
    - name: DB_USERNAME
      valueFrom:
        secretKeyRef:
          name: db-secret
          key: username
    - name: DB_PASSWORD
      valueFrom:
        secretKeyRef:
          name: db-secret
          key: password
    volumeMounts:
    - name: secret-volume
      mountPath: /etc/secrets
      readOnly: true
  volumes:
  - name: secret-volume
    secret:
      secretName: db-secret

# 同一镜像，不同环境，不同配置
# development
kubectl apply -f configmap-dev.yaml -f deployment.yaml

# production
kubectl apply -f configmap-prod.yaml -f deployment.yaml

# deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.19-alpine
        ports:
        - containerPort: 80
        resources:
          requests:
            memory: "64Mi"
            cpu: "100m"
          limits:
            memory: "128Mi"
            cpu: "200m"
---
# service.yaml
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
  - port: 80
    targetPort: 80