6、kubernetes资源清单之Pod控制器190714

一、Pod控制器的类别

• ReplicationController：早期唯一的控制器，已废弃

• ReplicaSet：控制Pod满足用户期望副本；标签选择器选择由自己管理的Pod副本；Pod资源模板完成Pod资源的新建。主要用于管理无状态的Pod，不建议直接使用此控制器

• Deployment：基于ReplicaSet控制器；建议使用此控制器，支持滚动更新和回滚，管理无状态应用

• DaemonSet：守护进程类的控制器，例如每台node都启动一个Pod一直持续下去

• Job：执行一次性的任务，完成后就退出，如果没有完成则重新构建一个Pod运行

• Cronjob：周期性运行的任务

• StatefulSet：管理有状态的应用，每个Pod都是单独管理

二、ReplicaSet控制器

• kubectl explain rs：获取帮助手册

# cat rs-damo.yaml
apiVersion: apps/v1
kind: ReplicaSet
metadata:  #ReplicaSet的metadata
  name: myapp-rs
  namespace: default
spec:  #ReplicaSet的spec
  replicas: 2
  selector:
    matchLabels:  #标签选择器，用于控制器选择控制符合条件的pod
      app: myapp
      release: canary
  template:
    metadata:
      name: myapp-pod  #此处pod名会被控制器的名字代替
      labels:  #此处为Pod的标签，必须符合控制器的标签选择器定义的条件
        app: myapp
        release: canary
    spec:
      containers:
      - name: myapp-container
        image: dongfeimg/myapp:v1
        ports:
        - name: http
          containerPort: 80
# kubectl get rs
# kubectl get pods

• 扩容/缩容

# kubectl edit rs myapp-rs
spec:
  replicas: 10  #将此值改

• 升级/回滚

# kubectl edit rs myapp-rs
    spec:
      containers:
      - image: dongfeimg/myapp:v2  #修改此值不能立即更新，原有pod删除后重建会升级到v2版本

三、Deployment控制器

• kubectl explain deploy

# cat deploy-damo.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
      app: myapp
      release: canary
  template:
    metadata:
      labels:
        app: myapp
        release: canary
    spec:
      containers:
      - name: myapp-container
        image: dongfeimg/myapp:v1
        ports:
        - name: http
          containerPort: 80
# kubectl apply -f deploy-damo.yaml  #声明式创建
# kubectl get deploy  #deploy控制rs
# kubectl get rs  #rs控制pod
# kubectl get pods

• 使用修改清单文件的方式扩容、缩容、更新和回滚等操作

# vim deploy-damo.yaml
spec:
  replicas: 3  #将副本扩容至3个
# kubectl apply -f deploy-damo.yaml

# vim deploy-damo.yaml
    spec:
      containers:
      - name: myapp-container
        image: dongfeimg/myapp:v2  #将版本更新为v2
# kubectl apply -f deploy-damo.yaml
# kubectl rollout history deployment myapp-deploy  #查看升级的历史信息

• 使用kubectl patch的方式扩容、缩容、更新和回滚等操作

# kubectl patch deployment myapp-deploy -p '{"spec":{"replicas":5}}'  #传入json格式的数组来实现扩容
# kubectl patch deployment myapp-deploy -p '{"spec":{"strategy":{"rollingUpdate":{"maxSurge":1,"maxUnavailable":0}}}}'  #"maxSurge":1 最大在更新pod数，"maxUnavailable":0 允许最大不可用的pod
# kubectl describe deployment myapp-deploy |grep RollingUpdateStrategy  #验证

• kubectl set image和kubectl rollout pause

# kubectl set image deployment myapp-deploy myapp-container=dongfeimg/myapp:v3 \  #将容器版本更新至v3
  && kubectl rollout pause deployment myapp-deploy  #在更新第一个的时候暂停，金丝雀发布
# kubectl rollout resume deployment myapp-deploy  #继续此前的更新

• kubectl rollout undo：回滚

# kubectl rollout history deployment myapp-deploy
# kubectl rollout undo deployment myapp-deploy --to-revision=1  #回滚至v1

四、DaemonSet控制器

• 在集群中符合选择器的node上一个pod，例如在每个节点上运行一个filebeat来收集日志
• kubectl explain ds

# cat ds-damo.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: redis
      role: logstor
  template:
    metadata:
      labels:
        app: redis
        role: logstor
    spec:
      containers:
      - name: redis
        image: redis:4.0
        ports:
        - name: redis
          containerPort: 6379
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: filebeat-ds
  namespace: default
spec:
  selector:
    matchLabels:
      app: filebeat
      release: stable
  template:
    metadata:
      labels:
        app: filebeat
        release: stable
    spec:
      containers:
      - name: filebeat-container
        image: dongfeimg/filebeat:5.6.5-alpine
        env:
        - name: REDIS_HOST
          value: redis.default.svc.cluster.local  #redis-server的主机名(svc)
        - name: REDIS_LOG_LEVEL
          value: info
# kubectl expose deployment redis --port=6379