Kubernetes-pod

目录

说明
Pod: k8s最小管理单元,一个pod中可以运行多个容器container
通过POD yaml和 kubectl run 命令运行POD有没有高可用

• 修改默认的namespace

kubectl config set-context --current --namespace=project1

• 创建一个POD

kubectl run --image=nginx --image-pull-policy=IfNotPresent --port=80 web-nginx 
-----------------
#:镜像下载策略：
1. Always
2. IfNotPresent
3. Never

• 查看POD日志

kubectl logs web-nginx -n project1

• 查看POD详细信息

kubectl describe pods web-nginx -n project1

• POD运行3个容器
  说明
  当pod中有多个主容器时，所有主容器都运行正常，POD才正常

trnuser@k8s:~/pod$ cat 3in1-pod.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: 3in1
  name: 3in1
spec:
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: web-test
    ports:
    - containerPort: 80
    resources: {}
  - image: busybox 
    imagePullPolicy: IfNotPresent
    name: busybox-1
    command: ["sh","-c","sleep 1000"]
    resources: {}
  - image: centos
    imagePullPolicy: IfNotPresent
    name: centos1
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Never
status: {}

• 初始化容器
  说明
  在一个pod中可以包含多个初始容器， 主容器必须等所有初始容器正常运行并完成时，才会运行主容器。

trnuser@k8s:~/pod/pod$ cat pod-init.yml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod8-init
  name: pod8-init
spec:
  containers:
  - image: nginx
    name: pod8
    imagePullPolicy: IfNotPresent
    resources: {}
    env:
    - name: MYSQL_PASSWORD
      value: 'redhat'
  initContainers:
  - image: busybox
    name: busybox-1
    imagePullPolicy: IfNotPresent 
    command: ["sh", "-c","sleep 20"]
    securityContext:
      privileged: true
  dnsPolicy: ClusterFirst
  restartPolicy: Never
status: {}

• POD访问

kubectl exet -it web-3in1 -- /bin/bash #默认进入主容器  POD中第一个容器为主容器
进入POD中不同容器，用-c 指定
kubectl exec -it web-nginx-4 -c c2  -- sh 

• 通过yaml文件创建POD

kubectl run --image=nginx --image-pull-policy=IfNotPresent --port=80 --dry-run=client web-nginx-3 -o yaml > pod1.yaml

• yaml文件中指定Node标签

trnuser@k8s:~/pod/pod$ cat pod1.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  nodeSelector:
    storage: ssd  ## 指定标签为ssd的NODE节点
  containers:
  - image: nginx
    name: pod1
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

• 静态POD

* etcd
* api-server
* controller-manager
* scheduler
* kube-proxy

说明
本地kubelet管理，kubelet服务会动态加载/etc/kubernetes/manifests/下的POD

trnuser@k8s:~/pod/pod$ sudo ls  /etc/kubernetes/manifests/
etcd.yaml  kube-apiserver.yaml	kube-controller-manager.yaml  kube-scheduler.yaml
trnuser@k8s:~/pod/pod$