初始化容器

kubernetes 1.3版本引入了init container 初始化容器特性。主要用于在启动应用容器（app container）前来启动一个或多个初始化容器，作为应用容器的一个基础。

# 查看要修改的内核参数
[root@kmaster ~]# sysctl -a|grep vm.overcommit_ratio
vm.overcommit_ratio = 50
# 输出yaml文件
[root@kmaster ~]# kubectl run initpod --image centos --image-pull-policy IfNotPresent --dry-run=client -o yaml -- sleep 3600> /root/pod_yaml/initpod.yaml
[root@kmaster ~]# cd pod_yaml/
[root@kmaster pod_yaml]# ls
initpod.yaml
# 修改yaml文件
[root@kmaster pod_yaml]# vim initpod.yaml 
[root@kmaster pod_yaml]# cat initpod.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: initpod
  name: initpod
spec:
  containers:
  - args:
    - sleep
    - "3600"
    image: centos
    imagePullPolicy: IfNotPresent
    name: initpod
    resources: {}
  initContainers:
  - name: initpod1
    image: alpine
    imagePullPolicy: IfNotPresent
    command: ["/sbin/sysctl","-w","vm.overcommit_ratio=55"]
    securityContext:
      privileged: true
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
# 编排Pod
[root@kmaster pod_yaml]# kubectl apply -f initpod.yaml 
pod/initpod created
[root@kmaster pod_yaml]# kubectl get pod -o wide 
NAME      READY   STATUS    RESTARTS   AGE   IP              NODE     NOMINATED NODE   READINESS GATES
initpod   1/1     Running   0          14s   10.244.69.210   knode2   <none>           <none>

# 查看knode2上是否已经修改
[root@knode2 ~]# sysctl -a|grep vm.overcommit_ratio
vm.overcommit_ratio = 55