pod控制器

一、前言

    在 Kubernetes 中，Pod 控制器是一种控制器对象，负责管理一组相关联的 Pod，并确保它们按照用户定义的规范进行运行。Pod 控制器负责 Pod 的创建、更新和删除，并确保它们的副本数保持在用户指定的范围内，Kubernetes 中常见的几种 Pod 控制器有以下几种ReplicaSet、Deployment、StatefulSet、DaemonSet、Job 和 CronJob

二、使用

deployment

Deployment 构建在 ReplicaSet 之上，提供了对 Pod 的声明式部署和更新。Deployment 允许用户定义应用程序的期望状态，并处理部署的滚动更新。它还支持回滚操作，以便在更新过程中发生问题时回滚到先前的稳定状态，用于部署无状态服务

apiVersion: apps/v1
kind: Deployment
metadata: 
  labels:
    app: api-gateway
  name: api-gateway
  namespace: java-service
spec:
  replicas: 2
  progressDeadlineSeconds: 600
  minReadySeconds: 10
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
    type: RollingUpdate
  selector:
    matchLabels:
      app: api-gateway
  template:
    metadata:
      labels:
        app: api-gateway
    spec:
      containers:
      - name: api-gateway
        image: harbor.apex.com/jdk/api-gateway:1.0.6
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 8888
        readinessProbe:
          tcpSocket:
            port: 8888
          initialDelaySeconds: 30
          periodSeconds: 10
          timeoutSeconds: 2
          successThreshold: 1
          failureThreshold: 2
        livenessProbe:
          tcpSocket:
            port: 8888
          initialDelaySeconds: 30
          periodSeconds: 10
          successThreshold: 1
          timeoutSeconds: 2
          failureThreshold: 2 
      restartPolicy: Always

daemonset

DaemonSet 用于在 Kubernetes 集群的每个节点上运行一个副本的 Pod。它通常用于部署运行系统级任务的 Pod，如日志收集、监控、网络代理等。DaemonSet 中的 Pod 在节点加入和离开集群时会自动调度和删除

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: filebeat
  namespace: elk
  labels:
    app: filebeat
spec:
  selector:
    matchLabels:
      app: filebeat
  template:
    metadata:
      labels:
        app: filebeat
    spec:
      serviceAccountName: filebeat
      terminationGracePeriodSeconds: 30
      containers:
      - name: filebeat
        image: elastic/filebeat:7.17.10
        args: [
          "-c", "/etc/filebeat.yml",
          "-e",
        ]
        env:
        - name: NODE_NAME
          valueFrom:
            fieldRef:
              fieldPath: spec.nodeName
        securityContext:
          runAsUser: 0
        resources:
          limits:
            cpu: 200m
            memory: 200Mi
          requests:
            cpu: 100m
            memory: 100Mi

statefulset

StatefulSet 用于管理有状态应用程序，如数据库。与 ReplicaSet 不同，StatefulSet 中的每个 Pod 都有唯一的标识符和稳定的网络标识符。StatefulSet 确保 Pod 的创建和删除顺序，并提供持久性存储，以便在 Pod 重新调度或故障转移时保留数据

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: rabbitmq
  namespace: rabbitmq
spec:
  podManagementPolicy: Parallel   #所有pod并行执行
  serviceName: rabbitmq-headless    #使用无头服务的svc
  selector:
    matchLabels:
      app: rabbitmq  
  replicas: 3  #副本数3
  template:
    metadata:
      labels:
        app: rabbitmq
      annotations:
        pod.alpha.kubernetes.io/initialized: "true"
    spec:
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            - labelSelector:
                matchExpressions:
                  - key: "app"
                    operator: In
                    values:
                      - rabbitmq
              topologyKey: "kubernetes.io/hostname"
      serviceAccountName: rabbitmq
      terminationGracePeriodSeconds: 10
      containers:
      - name: rabbitmq
        image: rabbitmq:3.10-management
        securityContext:
          runAsUser: 1000
        resources:
          limits:
            cpu: 2
            memory: 2Gi
          requests:
            cpu: 1
            memory: 1Gi
        volumeMounts:
          - name: config-volume
            mountPath: /etc/rabbitmq
          - name: rabbitmq-data
            mountPath: /var/lib/rabbitmq/mnesia
        ports:
          - name: http
            protocol: TCP
            containerPort: 15672
          - name: amqp
            protocol: TCP
            containerPort: 5672
        livenessProbe:
          exec:
            command: ["rabbitmq-diagnostics", "status"]
          initialDelaySeconds: 60
          periodSeconds: 60
          timeoutSeconds: 5
        readinessProbe:
          exec:
            command: ["rabbitmq-diagnostics", "status"]
          initialDelaySeconds: 20
          periodSeconds: 60
          timeoutSeconds: 5
        imagePullPolicy: Always
      volumes:
      - name: config-volume
        configMap:
          name: rabbitmq-config
          items:
          - key: rabbitmq.conf
            path: rabbitmq.conf
          - key: enabled_plugins
            path: enabled_plugins
  volumeClaimTemplates:
  - metadata:
      name: rabbitmq-data
    spec:
      storageClassName: "rabbitmq-pv"
      accessModes: [ "ReadWriteMany" ]
      resources:
        requests:
          storage: 30Gi

job、cronjob

Job 用于一次性任务的批处理作业，而 CronJob 用于周期性执行任务的作业。它们负责创建一个或多个 Pod 来执行任务，并在任务完成后终止 Pod。CronJob 可以按照预定的时间表周期性地执行 Job

apiVersion: batch/v1
kind: Job
metadata:
  name: data-backup-job
spec:
  template:
    spec:
      containers:
      - name: backup-container
        image: backup-image
        # 填写容器的其它配置
      restartPolicy: OnFailure

使用cronjob需要注意，二进制部署的k8s可以使用正常的时间，但是kubeadm部署的k8s会有时区问题，填写时间时需要在正常的时间减掉8小时，包括执行的程序里面包含时间的也需要减掉8小时，例如早上八点执行只需要填写0点

apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: data-cleanup-cronjob
spec:
  schedule: "0 0 * * *"   #每天凌晨执行数据清理任务
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: cleanup-container
            image: cleanup-image
            # 填写容器的其它配置
          restartPolicy: OnFailure
  # 设置 CronJob 的执行计划为每天凌晨执行