Kubernetes 初始化容器及静态Pod和标签

佚名 / 2023-05-22 / 原文

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。
init 1 --> init 2 --> 所有的初始化容器加载运行完成后，才能运行应用容器 --> app container

实战举例

# 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

# 查看Pod
[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

# 输出yaml文件
[root@kmaster pod_yaml]# kubectl run initpod2 --image centos --image-pull-policy IfNotPresent --dry-run=client -o yaml -- sleep 3600 > /root/pod_yaml/initpod2.yaml
[root@kmaster pod_yaml]# ls
initpod2.yaml  initpod.yaml

# 修改yaml文件
[root@kmaster pod_yaml]# vim initpod2.yaml 
[root@kmaster pod_yaml]# cat initpod2.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: initpod2
  name: initpod2
spec:
  containers:
  - args:
    - sleep
    - "3600"
    image: centos
    imagePullPolicy: IfNotPresent
    name: initpod2
    resources: {}
    volumeMounts:
    - name: testdir
      mountPath: /test
  initContainers:
  - name: alpine
    image: alpine
    imagePullPolicy: IfNotPresent
    command: ["sh","-c","echo 123 > /initest/test.txt"]
    volumeMounts:
    - name: testdir
      mountPath: /initest
  volumes:
  - name: testdir
    emptyDir: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

# 编排Pod
[root@kmaster pod_yaml]# kubectl apply -f initpod2.yaml 
pod/initpod2 created

# 查看状态
[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          32m     10.244.69.210    knode2   <none>           <none>
initpod2   1/1     Running   0          2m25s   10.244.195.149   knode1   <none>           <none>

# 进入容器查看是否挂载成功
[root@kmaster pod_yaml]# kubectl exec -it pods/initpod2 -- bash
Defaulted container "initpod2" out of: initpod2, alpine (init)
[root@initpod2 /]# cd /test/
[root@initpod2 test]# ls
test.txt
[root@initpod2 test]# cat test.txt 
123
[root@initpod2 test]#

静态Pod

注意不要在master上操作，因为master上跑的是集群核心静态pod，在node上去做

# 创建一个目录
[root@knode1 ~]# mkdir /etc/kubernetes/test

# 编辑配置文件
[root@knode1 ~]# vim /usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf
[root@knode1 ~]# cat /usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf 

# 在环境变量参数里面加上 --pod-manifest-path=/etc/kubernetes/test ，指向创建的目录 
# Note: This dropin only works with kubeadm and kubelet v1.11+
[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"
Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml --pod-manifest-path=/etc/kubernetes/test"
# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/sysconfig/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS

# 重启k8s
[root@knode1 ~]# systemctl daemon-reload 
[root@knode1 ~]# systemctl restart kubelet.service 

# 在test目录里面编写yaml文件
[root@knode1 ~]# cd /etc/kubernetes/test
[root@knode1 test]# kubectl run pod1 --image nginx --image-pull-policy IfNotPresent --dry-run=client -o yaml > pod1.yaml
[root@knode1 test]# cat pod1.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:

  - image: nginx
    imagePullPolicy: IfNotPresent
    name: pod1
    resources: {}
      dnsPolicy: ClusterFirst
      restartPolicy: Always
    status: {}
    [root@knode1 test]# 
    [root@knode1 test]# ls
    pod1.yaml

# 去master上查询，就会看到一个静态pod
[root@kmaster ~]# kubectl get pod
NAME          READY   STATUS              RESTARTS   AGE
pod1-knode1   0/1     ContainerCreating   0          14s

# 一旦移走了yaml文件，静态pod也将被删除
[root@knode1 test]# mv pod1.yaml /tmp/
[root@knode1 test]# ls
[root@kmaster ~]# kubectl get pod -o wide
No resources found in kongshuo namespace.