Kubernetes的Pod资源

Kubernetes命令

选项	作用
-n	指定名称空间
-f	指定资源清单
-c	指定连接POD中的容器
-o	查看pod指定格式信息
-w	动态查看，在查看日志或详细信息时

1）查看资源
kubectl get 资源名
kubectl get ns(namespace)
kubectl get node
kubectl get pod

2）创建资源
kubectl create 资源名 名称空间名字 --image(可指定镜像)
kubectl create ns 名称空间名字

3）给资源打标签
kubectl label 资源名 key=value
kubectl label pod key=value
kubectl label node key=value

4）删除资源
kubectl delete 资源名 名称空间
kubectl delete ns 名称空间

5）查看资源相关信息（排错）
kubectl describe 资源名

6）查看日志
kubectl logs pod pod名

7）启动pod
kubectl run pod

8）连接pod
kubectl exec -it pod名字 -- /bin/bash

9）连接pod中的指定容器
kubectl exec -it pod名字 -c 容器名 -- /bin/bash

Pod沉浸式体验

# 创建一个控制器资源
[root@master-1 ~]# kubectl create deployment  nginx --image=nginx:alpine

# 指定副本数量
--replicas=10
# 创建10个nginx
[root@master-1 ~]# kubectl create deployment  nginx10 --image=nginx:alpine --replicas=10
[root@master-1 ~]# kubectl get pod
NAME                       READY   STATUS    RESTARTS   AGE
nginx-565785f75c-vrgg7     1/1     Running   0          2m49s
nginx10-6cc8ffd95b-29zsb   1/1     Running   0          107s
nginx10-6cc8ffd95b-56v9d   1/1     Running   0          107s
nginx10-6cc8ffd95b-6gt8p   1/1     Running   0          106s
nginx10-6cc8ffd95b-95j69   1/1     Running   0          106s
nginx10-6cc8ffd95b-k8797   1/1     Running   0          107s
nginx10-6cc8ffd95b-l8lqw   1/1     Running   0          106s
nginx10-6cc8ffd95b-mhzgh   1/1     Running   0          107s
nginx10-6cc8ffd95b-nqjnx   1/1     Running   0          106s
nginx10-6cc8ffd95b-r5bpg   1/1     Running   0          107s
nginx10-6cc8ffd95b-vf4qw   1/1     Running   0          107s

# 查看pod指定格式信息（常用）
[root@master-1 ~]# kubectl get pod -o name
[root@master-1 ~]# kubectl get pod -o wide
[root@master-1 ~]# kubectl get pod -o json
[root@master-1 ~]# kubectl get pod -o yaml

# 将yaml语法导出
[root@master-1 ~]# kubectl get pod nginx10-6cc8ffd95b-29zsb -o yaml > /root/nginx-test.yaml
# 使用资源清单启动pod
[root@master-1 ~]# vim nginx-test.yml
apiVersion: v1
kind: Pod
metadata:
  name: nginx10-test
  namespace: default
spec:
  containers:
  - image: nginx:alpine
    imagePullPolicy: IfNotPresent
    name: nginx-test
## 启动容器（如果配置有变化，可以自动更新）
[root@master-1 ~]# kubectl apply -f nginx-test.yaml (二次运行)
## 启动容器（无法二次运行）
[root@master-1 ~]# kubectl create -f nginx-test.yaml (无法二次运行)
## 查看
[root@master-1 ~]# kubectl get pod nginx10-test 
NAME           READY   STATUS    RESTARTS   AGE
nginx10-test   1/1     Running   0          86s

# 删除控制器中的pod
[root@master-1 ~]# kubectl delete deployments nginx10

# 自己编写资源清单实践
[root@master-1 ~]# cat suibian.yml 
apiVersion: "v1"
kind: "Namespace"
metadata:
  name: ljy
---
apiVersion: "v1"
kind: "Pod"
metadata:
  name: nginx-niuniu
  namespace: ljy 
  labels:
    nginx: nn
spec: 
  containers:
  - image: nginx:alpine
    imagePullPolicy: IfNotPresent
    name: nginx
# 查看pod
[root@master-1 ~]# kubectl get pod -n ljy
NAME           READY   STATUS    RESTARTS   AGE
nginx-niuniu   1/1     Running   0        26s

# 单pod启动多容器
[root@master-1 ~]# vim suibian.yml
apiVersion: "v1"
kind: "Namespace"
metadata:
  name: ljy
---
apiVersion: "v1"
kind: "Pod"
metadata:
  name: nginx-niuniu
  namespace: ljy
  labels:
    nginx: nn
spec:
  containers:
  - name: nginx
    image: nginx:alpine
    imagePullPolicy: IfNotPresent

  - name: busybox
    imagePullPolicy: IfNotPresent
    image: busybox
    command: ["/bin/tail","-f","/etc/hosts"]
# 查看pod    
[root@master-1 ~]# kubectl get pod -n ljy
NAME           READY   STATUS    RESTARTS   AGE
nginx-niuniu   2/2     Running   0          18s

资源清单详解

# API的版本号（接口）
apiVersion: v1
#部署的资源类型
kind: Pod
# 元数据信息
metadata:
  # 资源的名称（pod名字）
  name: nginx81
  # 指定的名称空间（给pod启动在哪个名称空间）
  namespace: default
  # 打标签
  labels:
    标签名 key: value
    nginx: nn
# 自定义Pod资源的配置
spec:
  #定义容器相关信息
  containers:
    # 定义容器的名称
  - name: nginx01 c1
    # 定义容器基于哪个镜像,启动
    image: nginx:1.18
    # 镜像拉取规则     
    imagePullPolicy: Always（#总是拉取镜像）
                     Never（#永远不拉取镜像）
                     IfNotPresent（#如果不存在就拉取镜像，存在就不拉取镜像）

Kubernetes标签使用

## 查看标签
--show-labels
[root@master-1 ~]# kubectl get pod -n ljy --show-labels
NAME           READY   STATUS    RESTARTS   AGE   LABELS
nginx-niuniu   1/1     Running   0          17m   nginx=nn

## 打标签（node）
[root@master-1 ~]# kubectl label nodes node-1 CPU=1c

## 打标签（pod）
[root@master-1 ~]# kubectl label pod -n ljy nginx-niuniu nginx=niuniu

## 使用资源清单打标签
metadata:
  labels:
    nginx: nn

## 删除标签
[root@master-1 ~]# kubectl label nodes node-1 CPU-

## 根据标签找pod
[root@master-1 ~]# kubectl get pod --selector=nginx=nn -n ljy
NAME           READY   STATUS    RESTARTS   AGE
nginx-niuniu   1/1     Running   0          29m

## 根据标签删除
kubectl delete pod -l nginx=nn

重新认识Pod

共享网络

POD内的容器使用Container模式共享根容器的网络
容器看到的网络设备信息和根容器完全相同
POD内的多个容器可以使用localhost进行网络通讯
POD内的多个容器不能绑定相同的端口
POD的生命周期和根容器一样，如果根容器退出了，POD就退出了

# 测试一个pod中运行两个容器
[root@master-1 ~]# vim suibian.yml
apiVersion: "v1"
kind: "Namespace"
metadata:
  name: ljy
---
apiVersion: "v1"
kind: "Pod"
metadata:
  name: nginx-niuniu
  namespace: ljy
  labels:
    nginx: nn
spec:
  containers:
  - name: nginx
    image: nginx:alpine
    imagePullPolicy: IfNotPresent

  - name: busybox
    imagePullPolicy: IfNotPresent
    image: busybox
    command: ["/bin/tail","-f","/etc/hosts"]

# 指定pod启动在某个节点上
spec:
  # 指定node名为node-1的机器上，启动pod
  nodeName: node-1
  # 指定node标签为nginx: nn的机器上，启动pod
  nodeSelector:
    nginx: nn
  containers:
  - name: nginx
    image: nginx:alpine
    imagePullPolicy: IfNotPresent

  - name: busybox
    imagePullPolicy: IfNotPresent
    image: busybox
    command: ["/bin/tail","-f","/etc/hosts"]

共享存储（挂载）

默认情况下一个POD内的容器文件系统是互相隔离的
如果想让一个POD容器共享文件那么只需要定义一个Volume，然后两个容器分别挂载到这个Volume中
hostPath:将容器中的目录挂载到宿主机上指定的目录，为容器之间共享存储，具有数据持久化
emptyDir:在宿主机找个临时目录挂载，只为容器之间共享存储，无法数据持久化

# hostPath
[root@master-1 ~]# cat suibian.yml
apiVersion: "v1"
kind: "Namespace"
metadata:
  name: ljy
---
apiVersion: "v1"
kind: "Pod"
metadata:
  name: nginx-niuniu
  namespace: ljy 
  labels:
    nginx: nn
spec:
  volumes:
  - name: Guazai01
    hostPath:
      path: /data/test01

  volumes:
  - name: Guazai02
    hostPath:
      path: /data/test02

  containers:
  - name: nginx
    image: nginx:alpine
    imagePullPolicy: IfNotPresent
    volumeMounts:
    - name: Guazai01
      mountPath: /var/log/nginx/

  - name: busybox
    imagePullPolicy: IfNotPresent
    image: busybox
    command: ["/bin/tail","-f","/etc/hosts"]
    volumeMounts:
    - name: Guazai01
      mountPath: /opt/test

# emptyDir
[root@master-1 ~]# cat suibian.yml
apiVersion: "v1"
kind: "Namespace"
metadata:
  name: ljy
---
apiVersion: "v1"
kind: "Pod"
metadata:
  name: nginx-niuniu
  namespace: ljy 
  labels:
    nginx: nn
spec:
  volumes:
  - name: Guazai01
    hostPath:
      path: /data/test01

  volumes:
  - name: Guazai02
    emptyDir: {}

  containers:
  - name: nginx
    image: nginx:alpine
    imagePullPolicy: IfNotPresent
    volumeMounts:
    - name: Guazai02
      mountPath: /var/log/nginx/

  - name: busybox
    imagePullPolicy: IfNotPresent
    image: busybox
    command: ["/bin/tail","-f","/etc/hosts"]
    volumeMounts:
    - name: Guazai02
      mountPath: /opt/test

使用资源清单启动mysql

[root@master-1 tmp]# mkdir /data
[root@master-1 tmp]# cd /data/

[root@master-1 data]# vim mysql.yml
apiVersion: "v1"
kind: "Pod"
metadata:
  name: mysql57
spec:
  nodeName: node-1
  volumes:
  - name: mysql-data
    hostPath:
      path: /data/mysql
  containers:
  - name: mysql-container
    image: mysql:5.7
    imagePullPolicy: IfNotPresent
    env:
    - name: MYSQL_ROOT_PASSWORD
      value: '123'
    - name: MYSQL_DATABASE
      value: 'wordpress'
    - name: MYSQL_USER
      value: 'wp_user'
    - name: MYSQL_PASSWORD
      value: '123'
    args:
    - --character-set-server=utf8mb4
    - --collation-server=utf8mb4_unicode_ci
    volumeMounts:
    - name: mysql-data
      mountPath: /var/lib/mysql

Pod对容器的封装和应用

第一种：全部放一个pod里

第二种：Wordpress和MySQL分开

那么如何扩容呢？如果第一种方案大家会发现没有办法很好的扩容，因为数据库和wordpress已经绑定成一个整体了，扩容wordpress就得扩容mysql。而第二种方案就要灵活的多。

Pod的生命周期

initCoantainers 初始化容器

初始化容器是指，在主容器启动之前，我们可以让他做一些准备工作。

比如：

1.两个容器做了共享存储，那么我们可以让它先启动一个容器，来对目录进行更改用户和授权
2.容器需要连接数据库，那么可以让初始化容器检测数据库是否可以正常连接，如果可以再启动主容器

初始化容器应用示例

[root@master-1 ~]# vim /opt/nginx-init.yaml
apiVersion: "v1"
kind: "Pod"
metadata:
  name: nginx-init
spec:
  volumes:
  - name: nginx-data
    emptyDir: {}
  initContainers:
  - name: nginx-init-container
    image: busybox
    imagePullPolicy: IfNotPresent
    args: ['/bin/sh','-c','echo k8s nginx init > /usr/share/nginx/html/index.html']
    volumeMounts:
    - name: nginx-data
      mountPath: /usr/share/nginx/html/

  containers:
  - name: nginx-container
    image: nginx:alpine
    imagePullPolicy: IfNotPresent
    volumeMounts:
    - name: nginx-data
      mountPath: /usr/share/nginx/html/

钩子

Poststart

cni：容器网络接口
cri：容器运行时接口
csi：容器存储接口

## hook
Poststart：在容器启动创建后，立即执行，但时间不能太长，否则容器不会是running状态
exec:执行命令
httpGet:检测http
tcpSocket:检测端口

## Poststart应用示例
[root@master-1 tmp]# vim poststart.yml
apiVersion: v1
kind: Pod
metadata:
  name: nginx-poststart
  labels:
    name: nginx-poststart
spec:
  containers:
  - name: nginx-poststart
    image: nginx:alpine
    imagePullPolicy: IfNotPresent
    lifecycle:
      postStart:
        exec:
          command:
          - "/bin/sh"
          - "-c"
          - "echo k8s poststart > /usr/share/nginx/html/index.html"

[root@master-1 tmp]# curl 10.2.2.28
k8s poststart

prestop

prestop：在容器停止前，执行一些命令，主要用于优雅关闭程序
exec:执行命令
httpGet:检测http
tcpSocket:检测端口

## prestop应用示例
[root@master-1 tmp]# vim prestop.yml
apiVersion: v1
kind: Pod
metadata:
  name: nginx-poststart
  labels:
    name: nginx-poststart
spec:
  volumes:
  - name: test
    hostPath:
      path: /data/nginx
  containers:
  - name: nginx-prestop
    image: nginx:alpine
    imagePullPolicy: IfNotPresent
    volumeMounts:
    - name: test
      mountPath: /usr/share/nginx/html/
    lifecycle:
      preStop:
        exec:
          command:
          - "/bin/sh"
          - "-c"
          - "echo bye > /usr/share/nginx/html/index.html"
      postStart:
        exec:
          command:
          - "/bin/sh"
          - "-c"
          - "echo k8s prestop > /usr/share/nginx/html/index.html"

[root@master-1 tmp]# curl 10.2.2.29
k8s prestop

健康检查探针

initialDelaySeconds: 第一次执行探针需要在容器启动后等待的时候时间
periodSeconds: 容器启动后每隔多少秒执行一次存活探针
timeoutSeconds: 探针超时时间，默认1秒，最小1秒
successThreshold: 探针失败后最少连续探测成功多少次才被认定成功，默认1次，如果是liveness必须为1
failureThreshold: 探针成功后被视为失败的探测的最小连续失败次数。默认3次。最小值为1

存活态探针(livenessProbe)

存活态探针（存活性探针）：检测pod中容器的应用是否存活
exec:执行命令检测
httpGet:检测http
tcpSocket:检测端口

## 存活态探针示例（exec）
apiVersion: v1
kind: Pod
metadata:
  name: liveness
  labels:
    name: liveness
spec:
  volumes:
  - name: test
    hostPath:
      path: /data/test
  containers:
  - name: liveness
    image: nginx:alpine
    imagePullPolicy: IfNotPresent
    volumeMounts:
    - name: test
      mountPath: /usr/share/nginx/html/
    lifecycle:
      postStart:
        exec:
          command:
          - "/bin/sh"
          - "-c"
          - "echo test liveness > /usr/share/nginx/html/index.html"
    livenessProbe:
      exec:
        command:
        - "/bin/sh"
        - "-c"
        - "cat /usr/share/nginx/html/index.html"
      initialDelaySeconds: 3
      periodSeconds: 1
    resources:
      limits:
        memory: "128Mi"
        cpu: "500m"

## 存活态探针示例（httpGet）
apiVersion: v1
kind: Pod
metadata:
  name: liveness
  labels:
    name: liveness
spec:
  volumes:
  - name: test
    hostPath:
      path: /data/test
  containers:
  - name: liveness
    image: nginx:alpine
    imagePullPolicy: IfNotPresent
    volumeMounts:
    - name: test
      mountPath: /usr/share/nginx/html/
    lifecycle:
      postStart:
        exec:
          command:
          - "/bin/sh"
          - "-c"
          - "echo test liveness > /usr/share/nginx/html/index.html"
    livenessProbe:
      httpGet:
        path: /
        port: 80
      initialDelaySeconds: 3
      periodSeconds: 1
    resources:
      limits:
        memory: "128Mi"
        cpu: "500m"

# 存活态探针测试（自动恢复）
[root@node-1 test]# ll
total 4
-rw-r--r-- 1 root root 14 Sep 21 16:36 index.html
[root@node-1 test]# rm -f index.html 
[root@node-1 test]# ll
total 0
[root@node-1 test]# ll
total 0
[root@node-1 test]# ll
total 4
-rw-r--r-- 1 root root 14 Sep 21 16:37 index.html
[root@node-1 test]# ll
total 4
-rw-r--r-- 1 root root 14 Sep 21 16:37 index.html

就绪态探针(readinessProbe)

就绪态探针（就绪性探针）：检测pod中容器的应用是否都准备就绪，未准备就绪时，是不对外提供服务（不开放流量）
exec:执行命令检测
httpGet:检测http
tcpSocket:检测端口

# 就绪态探针示例
apiVersion: v1
kind: Pod
metadata:
  name: livenss-pod
spec:
  containers:
  - name: livenss-pod
    image: nginx:alpine
    lifecycle:
      postStart:
        exec:
          command:
          - "/bin/sh"
          - "-c"
          - "sleep 100;echo ok > /usr/share/nginx/html/health.html"
    readinessProbe:
      httpGet:
        path: /actuator/health
        port: 8080
      initialDelaySeconds: 5
      timeoutSeconds: 3
      periodSeconds: 3
      successThreshold: 3
      failureThreshold: 3
    livenessProbe:
      httpGet:
        path: /health.html
        port: 80
      initialDelaySeconds: 3
      periodSeconds: 3
    resources:
      limits:
        memory: "128Mi"
        cpu: "500m"

# 检测
## 启动时curl了以后是404
[root@master-1 tmp]# curl 10.2.2.31/health.html
<html>
<head><title>404 Not Found</title></head>
<body>
<center><h1>404 Not Found</h1></center>
<hr><center>nginx/1.21.5</center>
</body>
</html>
## 启动时curl初始的index是welcome to nginx
[root@master-1 tmp]# curl 10.2.2.31
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>
## 启动后100秒以后重新curl
[root@master-1 tmp]# curl 10.2.2.31/health.html
ok

service中添加clusterIP尝试

[root@master-1 tmp]# vim livenessprode.yml 
apiVersion: v1
kind: Pod
metadata:
  name: liveness
  labels:
    name: liveness
spec:
  volumes:
  - name: test
    hostPath:
      path: /data/test
  containers:
  - name: liveness
    image: nginx:alpine
    imagePullPolicy: IfNotPresent
    volumeMounts:
    - name: test
      mountPath: /usr/share/nginx/html/
    lifecycle:
      postStart:
        exec:
          command:
          - "/bin/sh"
          - "-c"
          - "echo test liveness > /usr/share/nginx/html/index.html"
    livenessProbe:
      exec:
        command:
        - "/bin/sh"
        - "-c"
        - "cat /usr/share/nginx/html/index.html"
      initialDelaySeconds: 3
      periodSeconds: 1
    resources:
      limits:
        memory: "128Mi"
        cpu: "500m"
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-svc
spec:
  type: ClusterIP
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  selector:
    app: nginx

# 启动pod
[root@master-1 tmp]# kubectl apply -f livenessprode.yml 
pod/liveness created
service/nginx-svc created

# 查看service
[root@master-1 tmp]# kubectl get service
NAME         TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.1.0.1      <none>        443/TCP   3d5h
nginx-svc    ClusterIP   10.1.160.35   <none>        80/TCP    15s

# 查看endpoints
[root@master-1 tmp]# kubectl get endpoints
NAME         ENDPOINTS         AGE
kubernetes   10.0.0.110:6443   3d5h
nginx-svc    10.2.1.5:80       72s

# curl集群ip显示集群内nginx页面
[root@master-1 tmp]# curl 10.1.160.35
<h1>Welcome to nginx!</h1>

wordpress与mysql搭建（存活态探针）

mysql搭建

apiVersion: "v1"
kind: "Namespace"
metadata:
  name: wordpress
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
  namespace: wordpress
  labels:
    app: mysql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: mysql
    spec:
      containers:
      - image: mysql:5.7
        name: mysql
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 3306
          name: dbport
        env:                      #环境编排，进入数据库中创建Wordpress数据库和WordPress用户
        - name: MYSQL_ROOT_PASSWORD
          value: PassWord
        - name: MYSQL_DATABASE
          value: wordpress
        - name: MYSQL_USER
          value: wordpress
        - name: MYSQL_PASSWORD
          value: wordpress
        volumeMounts:
        - name: db
          mountPath: /var/lib/mysql     #mysql数据存放的容器目录
        resources: {}
      volumes:
      - name: db
        hostPath:
          path: /var/lib/mysql        #容器目录中的数据映射到本地目录中
status: {}
---
apiVersion: v1
kind: Service
metadata:
  name: mysql
  namespace: wordpress
spec:
  selector:
    app: mysql
  ports:
  - name: mysqlport
    protocol: TCP
    port: 3306
    targetPort: dbport

# 查看mysql暴露出的ip是什么
[root@master-1 ~]# kubectl get pod -n wordpress -o wide
NAME                     READY   STATUS    RESTARTS   AGE     IP          NODE     NOMINATED NODE   READINESS GATES
mysql-67457648cd-flctn   1/1     Running   0          3m50s   10.2.2.24   node-2   <none>           <none>

wordpress搭建（存活态探针）

apiVersion: apps/v1
kind: Deployment
metadata:
  name: wordpress
  namespace: wordpress
  labels:
    app: wordpress
spec:
  replicas: 1
  selector:
    matchLabels:
      app: wordpress
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: wordpress
    spec:
      containers:
      - name: wordpress
        image: wordpress
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 80
          name: wdport
        env:
        - name: WORDPRESS_DB_HOST
          value: 10.2.2.24:3306 #连接数据库，这里的ip地址查看mysql启动时的ip
        - name: WORDPRESS_DB_USER
          value: wordpress
        - name: WORDPRESS_DB_PASSWORD
          value: wordpress
        livenessProbe:
          httpGet:
            path: /
            port: 80
          initialDelaySeconds: 30
          periodSeconds: 10
status: {}
---
apiVersion: v1
kind: Service
metadata:
  name: wordpress
  namespace: wordpress
spec:
  type: NodePort
  selector:
    app: wordpress
  ports:
  - name: wordpressport
    protocol: TCP
    port: 80
    targetPort: wdport

# 查看对外暴露的端口
[root@master-1 ~]# kubectl get svc -n wordpress
NAME        TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
mysql       ClusterIP   10.1.147.212   <none>        3306/TCP       5m54s
wordpress   NodePort    10.1.235.4     <none>        80:30886/TCP   91s

存活态探针测试

连接

# 删除配置文件
root@wordpress-7897cdc46d-wm6mc:/var/www/html# rm -fr wp-config.php

过后会自动拉起