Deployment / StatefulSet / DaemonSet / Job / CronJob

apiVersion: apps/v1        # Deployment 属于 apps 组,v1 版本
kind: Deployment
metadata:
  name: nginx-deploy         # 1. Deployment 自己的名字
spec:
  replicas: 3                # 2. 期望几份副本?3 个一模一样的 Pod
  selector:                  # 3. 哪些 Pod 归这个 Deployment 管?
    matchLabels:
      app: nginx             #    标签匹配规则:app=nginx
  template:                  # 4. Pod 模板(就是 Pod 的 metadata + spec)
    metadata:
      labels:
        app: nginx           #    必须和 3 的 selector 匹配,否则创建报错
    spec:                    #    ↓ 从这里开始和裸 Pod 的 spec 完全一样 ↓
      containers:
      - name: nginx
        image: nginx:1.25
        ports:
        - containerPort: 80

# 显式配置
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0

spec:
  strategy:
    type: Recreate   # 全删再全建,中间服务中断

# 普通 Service
kind: Service
spec:
  clusterIP: 10.96.0.1   ← 分配一个虚拟 IP
  → DNS 返回 10.96.0.1 → iptables 负载均衡 → 随机后端 Pod

# Headless Service
kind: Service
spec:
  clusterIP: None        ← 不分配虚拟 IP
  → DNS 直接返回所有后端 Pod 的 IP 列表 → 调用方自己选连哪个

# Headless Service 定义
apiVersion: v1
kind: Service
metadata:
  name: redis-svc
spec:
  clusterIP: None           # ← Headless:不分配 ClusterIP
  selector:
    app: redis
  ports:
  - port: 6379

# DNS 解析结果:
redis-svc.default.svc.cluster.local        → 所有 Pod IP(A 记录列表)
redis-cluster-0.redis-svc.default.svc...   → 只有 redis-cluster-0 的 IP
redis-cluster-1.redis-svc.default.svc...   → 只有 redis-cluster-1 的 IP

# 应用里可以这样连:
redis-cluster-0.redis-svc:6379   → 始终连到同一个 Pod
# Pod 被重建,IP 变了,DNS 自动更新,名字不变

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  serviceName: mysql-svc      # 必须关联一个 Headless Service
  replicas: 3
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:8.0
        volumeMounts:
        - name: data
          mountPath: /var/lib/mysql
  volumeClaimTemplates:       # ← 自动为每个 Pod 生成 PVC
  - metadata:
      name: data
    spec:
      accessModes: ["ReadWriteOnce"]
      resources:
        requests:
          storage: 100Gi

# 产生的 PVC:
$ kubectl get pvc
NAME                   STATUS   CAPACITY   POD
data-mysql-0           Bound    100Gi      mysql-0
data-mysql-1           Bound    100Gi      mysql-1
data-mysql-2           Bound    100Gi      mysql-2

# 关键行为:
# mysql-0 挂了重建 → 新 Pod 还是叫 mysql-0,重新挂载 data-mysql-0 PVC → 数据还在
# mysql-1 缩容 → data-mysql-1 PVC 不会被删(保留数据,手动扩容恢复)
# 手动删 PVC 才会丢数据

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: fluentd-logger
spec:
  selector:
    matchLabels:
      name: fluentd
  template:
    metadata:
      labels:
        name: fluentd
    spec:
      containers:
      - name: fluentd
        image: fluentd:latest
        volumeMounts:
        - name: varlog
          mountPath: /var/log      # 读宿主机的日志目录
      volumes:
      - name: varlog
        hostPath:
          path: /var/log

spec:
  template:
    spec:
      nodeSelector:
        accelerator: nvidia       # 只有带这个 label 的节点才部署

apiVersion: batch/v1
kind: Job
metadata:
  name: db-migrate
spec:
  backoffLimit: 4           # 最多重试 4 次(超出则 Job = Failed)
  completions: 1            # 需要多少个 Pod 成功完成
  parallelism: 1            # 最多同时跑几个 Pod
  template:
    spec:
      restartPolicy: Never  # Job 必须用 Never 或 OnFailure
      containers:
      - name: migrate
        image: my-app:migrate
        command: ['./migrate.sh']

# 工作队列模式:100 条待处理任务,5 个 worker 并行
spec:
  completions: 100          # 总共要跑完 100 个 Pod
  parallelism: 5            # 同时最多 5 个 worker
  backoffLimit: 6
  template:
    spec:
      restartPolicy: Never
      containers:
      - name: worker
        image: worker:latest
        env:
        - name: TASK_ID
          valueFrom:
            fieldRef:
              fieldPath: metadata.name   # 每个 Pod 根据名字处理不同任务

apiVersion: batch/v1
kind: CronJob
metadata:
  name: nightly-backup
spec:
  schedule: "0 2 * * *"         # 每天凌晨 2:00(UTC)
  concurrencyPolicy: Forbid     # 如果上次 Job 还在跑,跳过这次
  successfulJobsHistoryLimit: 3 # 保留最近 3 个成功的 Job
  failedJobsHistoryLimit: 1     # 保留最近 1 个失败的 Job
  jobTemplate:                  # ← 就是完整的 Job spec
    spec:
      backoffLimit: 2
      template:
        spec:
          restartPolicy: Never
          containers:
          - name: backup
            image: backup-tool:latest
            command: ['./backup.sh']