kubernetes之LimitRange

需求：集群管理为每一个pod配置Requests和Limits限制是繁琐的,
解决方案： kubernetes提供了LimitRange机制对pod和容器的Requests和Limits作出限制
LimitRange几种限制方式： 最大最小范围, Requests或Limits的默认值, limits与Requests的最大比例上限
1.创建namespace

kubectl create namespace limitrange-example

2.LimitRange资源对象

apiVersion: v1
kind: LimitRange
metadata:
  name: mylimits
  namespace: limitrange-example
spec:
  limits:
  - max:
      cpu: "2"
      memory: 4Gi
    min:
      cpu: 200m
      memory: 6Mi
    maxLimitRequestRatio:
      cpu: 2
      memory: 2
    type: Pod

  - default:
      cpu: 300m
      memory: 200Mi
    defaultRequest:
      cpu: 200m
      memory: 100Mi
    min:
      cpu: 100m
      memory: 3Mi      
    max:
      cpu: "2"
      memory: 1Gi

    maxLimitRequestRatio:
      cpu: 5
      memory: 4
    type: Container

3.查看limitrange对象信息

kubectl describe limitrange mylimits -n limitrange-example

说明

type为Pod: 
    min表示是pod中所有容器的requests值的总和下限 
    max表示pod中所有容器的limits值的总和上限
    maxLimitRequestRatio表示是pod中所有容器的Limits值总和与Requests值总和的比例上限

type为Requests:
    min表示是pod中的容器的requests值的下限 
    max表示pod中容器的limits值的上限
    defaultRequest: pod中未指定Requests值的容器的默认Requests值
    default表示pod中未指定Limits值的容器的默认Limits值
    maxLimitRequestRatio表示是pod中所有容器的Limits值总和与Requests值比例上限

4.创建pod

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: limitrange-example
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.11
        ports:
        - containerPort: 80

说明： 由于该pod未配置Requests和Limits, 所以使用默认定义的Requests和Limits值

5.配置超过资源限制的pod, 结果是无法创建的

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: limitrange-example
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.11
        ports:
        - containerPort: 80
        resources:
          limits:
            cpu: "3"
            memory: 2Gi