使用initcontainer 修改pod 中容器的内核参数

1. 在pod 中使用的案例

apiVersion: v1
kind: Pod
metadata:
  name: test-sysctl-init
  namespace: default
spec:
  containers:
  - image: nginx
    imagePullPolicy: Always
    name: nginx
    ports:
    - containerPort: 80
      protocol: TCP
  initContainers:
  - image: busybox
    command:
    - sh
    - -c
    - echo 65535 > /proc/sys/net/core/somaxconn
    imagePullPolicy: Always
    name: setsysctl
    securityContext:
      privileged: true

2. 在无状态服务中配置的案例

apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: '2'
  creationTimestamp: '2021-02-25T07:26:06Z'
  generation: 2
  labels:
    app: nginx
  name: nginx
  namespace: default
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: nginx
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - env:
            - name: PKG_RELEASE
              value: 2~buster
          image: 'nginx:stable'
          imagePullPolicy: IfNotPresent
          name: nginx
          ports:
            - containerPort: 80
              protocol: TCP
          resources:
            requests:
              cpu: 100m
              memory: 200Mi
          terminationMessagePath: /dev/termination-log
          terminationMessagePolicy: File
          volumeMounts:
            - mountPath: /etc/localtime
              name: volume-localtime
      dnsPolicy: ClusterFirst
      initContainers:
        - command:
            - /bin/sh
            - '-c'
            - |
              mount -o remount rw /proc/sys
              sysctl -w net.core.somaxconn=65535
              sysctl -w net.ipv4.ip_local_port_range="1024 65535"
              sysctl -w fs.file-max=1048576
              sysctl -w fs.inotify.max_user_instances=16384
              sysctl -w fs.inotify.max_user_watches=524288
              sysctl -w fs.inotify.max_queued_events=16384
          image: 'busybox:latest'
          imagePullPolicy: IfNotPresent
          name: init-sysctl
          resources: {}
          securityContext:
            capabilities:
              add:
                - SYS_ADMIN
              drop:
                - ALL
            procMount: Default
          terminationMessagePath: /dev/termination-log
          terminationMessagePolicy: File
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
      volumes:
        - hostPath:
            path: /etc/localtime
            type: ''
          name: volume-localtime

3. 验证修改参数是否生效
   登录到创建好的pod 内执行 cat /proc/sys/net/core/somaxconn 查看参数是否与设置中的数值一致(默认值为128)。