21.Pod的limit和request和资源监控收集服务Heapster

容器的资源需求，资源限制 

    requests：需求，最低保障；
    limits：限制，硬限制； 

    CPU:
        1颗逻辑CPU
        =,millicores
            500m=.5CPU 

    内存：
        E、P、T、G、M、K
        Ei、Pi 

    QoS：
        Guranteed：每个容器
            同时设置CPU和内存的requests和limits.
                cpu.limits=cpu.requests
                memory.limits=memory.request
        Burstable:
            至少有一个容器设置CPU或内存资源的requests属性
        BestEffort：没有任何一个容器设置了requests或limits属性；最低优先级别； 

官方文档对需求和限制的解释

spec.containers[].resources.limits.cpu
spec.containers[].resources.limits.memory
spec.containers[].resources.requests.cpu
spec.containers[].resources.requests.memory

apiVersion: v1
kind: Pod
metadata:
  name: frontend
spec:
  containers:
  - name: db
    image: mysql
    env:
    - name: MYSQL_ROOT_PASSWORD
      value: "password"
    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"
  - name: wp
    image: wordpress
    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"

进行一个简单的压测

[root@master limit]# cat pod-demo.yml
apiVersion: v1
kind: Pod
metadata:
  name: pod-limit
  namespace: default
  labels:
    app: myapp
    2sdlfj: dashazi
spec:
  containers:
  - name: stress-ng
    image: ikubernetes/stress-ng
    command: ["/usr/bin/stress-ng","-m 1","-c 1","--metrics-brief"]
    resources:
      requests:
        cpu: "500m"
        memory: "256Mi"
      limit:
        cpu: "500m"
        memory: "256Mi"
  nodeSelector:
    location: slave1

kubectl  exec  pod-limit -- top

Mem: 1994208K used, 52860K free, 113228K shrd, 328K buff, 194776K cached
CPU: 18% usr 28% sys 0% nic 30% idle 11% io 0% irq 11% sirq
Load average: 8.07 6.10 3.87 6/740 123
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
6 1 root R 6892 0% 0 11% {stress-ng-cpu} /usr/bin/stress-ng
84 0 root R 1500 0% 0 0% top
123 7 root R 262m 13% 1 0% {stress-ng-vm} /usr/bin/stress-ng
7 1 root S 6244 0% 1 0% {stress-ng-vm} /usr/bin/stress-ng
1 0 root S 6244 0% 1 0% /usr/bin/stress-ng -m 1 -c 1 --met
21 0 root S 1504 0% 0 0% top

资源监控收集服务Heapster（已弃用）

[root@master limit]# kubectl top node
Error from server (NotFound): the server could not find the requested resource (get services http:heapster:)