kubernetes之配置namespace中Pod的总数

简介

限制namespace中运行的Pod个数，设置Pod配额（Quota）。

备注：此文档参考官方文档，并加以自己的理解。如有误导性的内容，请批评指正。

namepace的Pod配置示例

创建namespace

# kubectl create namespace quota-pod-example

创建一个ResourceQuota对象。文件名：quota-pod.yaml

apiVersion: v1
kind: ResourceQuota
metadata:
  name: pod-demo
spec:
  hard:
    pods: "2"

# kubectl apply -f /root/k8s-example/namespace/quota-pod.yaml --namespace=quota-pod-example

查看输出结果

# kubectl get resourcequota pod-demo --namespace=quota-pod-example --output=yaml

从结果中可以看到，Pod配额为2个，使用了0个

spec:
  hard:
    pods: "2"
status:
  hard:
    pods: "2"
  used:
    pods: "0"

创建一个Deployment资源，启动一个3副本的Pod。文件名：quota-pod-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: pod-quota-demo
spec:
  selector:
    matchLabels:
      purpose: quota-demo
  replicas: 3
  template:
    metadata:
      labels:
        purpose: quota-demo
    spec:
      containers:
      - name: pod-quota-demo
        image: nginx

# kubectl apply -f /root/k8s-example/namespace/quota-pod-deployment.yaml --namespace=quota-pod-example

查看Deployment资源详情

# kubectl get deployment pod-quota-demo --namespace=quota-pod-example --output=yaml

从输出结果可以看出，已创建2个Pod，但是由于该namespace的Pod配额是2个，所以第3个无法被创建

spec:
  ...
  replicas: 3
...
status:
  availableReplicas: 2
...
lastUpdateTime: 2017-07-07T20:57:05Z
    message: 'unable to create pods: pods "pod-quota-demo-1650323038-" is forbidden:
      exceeded quota: pod-demo, requested: pods=1, used: pods=2, limited: pods=2'

查看正在运行的Pod

# kubectl get po -n quota-pod-example
NAME                              READY   STATUS    RESTARTS   AGE
pod-quota-demo-56d6f96f68-8c9px   1/1     Running   0          6m43s
pod-quota-demo-56d6f96f68-zq6v6   1/1     Running   0          6m43s

实验完毕，删除Pod

# kubectl delete namespace quota-pod-example

总结

1、为了充分利用资源，可以给namespace定义Pod配置，当超过该Pod配额值时，Pod不会被创建。