k8s

制作镜像

第一个pod

搭建Harbor仓库

重启策略

启动命令

pod基本命令

设置环境变量

数据持久化和共享-hostPath

数据持久化和共享-emptyDir

JSON格式编写pod文件

ConfigMap

pod共享宿主机网络

pod的生命周期

pod的生命周期函数

通过环境变量获取pod和container的信息

通过文件挂载获取pod和container的信息

健康检查和服务可用性检查

制作镜像

一个简单的springboot项目

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0"          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.datang</groupId> <artifactId>dockerdemo</artifactId> <version>1.0-SNAPSHOT</version> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.3.2.RELEASE</version> </parent> <properties> <maven.compiler.source>8</maven.compiler.source> <maven.compiler.target>8</maven.compiler.target> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>

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package com.datang.dockerdemo.controller;  import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication;  @SpringBootApplication public class Application {     public static void main(String[]args){         SpringApplication.run(Application.class,args);     } }

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package com.datang.dockerdemo.controller;  import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController;  import java.net.InetAddress; import java.net.InetSocketAddress;  @RestController public class Rest {     @GetMapping("test")     public String test() {         String s = "~~~~~~~~~~";         try {             InetAddress localHost = InetAddress.getLocalHost();             String hostAddress = localHost.getHostAddress();             String canonicalHostName = localHost.getCanonicalHostName();             String hostName = localHost.getHostName();             s = s + "--------"+hostAddress + "-------"+ hostName;         } catch (Exception e) {             throw new RuntimeException(e);         }         return s;     } }

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dockerfile文件

基于 centos7作为基础镜像,然后再里边yum一个vim插件,进入/usr/local目录,创建test目录,将虚拟机上的jar包和jdk压缩包拷贝到镜像内的/usr/local/test里,

进入/usr/local/test,解压jdk,设置jdk环境变量,执行jar包。这个dockerfile就做了这些事。需要注意的是,设置环境变量时一定要看自己解压好的jdk目录名

FROM centos:7  RUN yum install -y vim  WORKDIR /usr/local  RUN mkdir test   COPY dockerdemo.jar /usr/local/test COPY jdk8.tar.gz /usr/local/test  WORKDIR /usr/local/test RUN tar -zxvf jdk8.tar.gz  ENV JAVA_HOME /usr/local/test/jdk1.8.0_291 ENV PATH $JAVA_HOME/bin:$PATH  ENTRYPOINT ["java","-jar","/usr/local/test/dockerdemo.jar","&"]

(master节点)在这个目录下执行 docker build -t myapp . (注意最后边有个  . )

测试镜像是否可用

docker run -itd -p 9999:8080 myapp

第一个pod

编写pod.yaml(master节点)

apiVersion: v1 #版本号 kind: Pod #类型 metadata:   name: poddemo1 #pod名称   labels: # 标签     k1: v1 #key和value任意都可以 spec: #容器内容   containers: #设置容器     - name: myapp01 #容器名       image: myapp #依赖docker镜像       imagePullPolicy: Never #镜像拉去策略 Never表示只从本地拉去镜像,Always表示每次都尝试拉去镜像,IfNotPresent如果本地不存在则拉去       ports: #端口策略         - name: tomcatport #端口名           containerPort: 8080 #容器需要监听的端口

运行命令 kubectl create -f poddemo1.yaml

查看 pod是否创建成功 kubectl get pod

报错说找不到镜像,原因是创建的pod分发到了node节点,但是node节点是真的没有这个image

将镜像导入到node后重新运行发现pod状态一直不对。

查看pod状态

kubectl describe pod poddemo1

发现这个错误提示说Java path 一拍头想起来了,镜像里那个jdk解压后的文件夹名字肯定写错了。重新打包镜像后重新创建成功。

通过查看pod的IP

kubectl get pod -o wide

然后在任何一个k8s节点上都可以访问

搭建Harbor仓库

上边的例子缺点就在于,master节点上有的镜像node节点没有,需要手动上传,这是不自动的。我们创建一个自己的harbor仓库,就可以处理这个问题。我这边的harbor仓库是按照下边的博客搭建的,流程是没问题的。

https://blog.csdn.net/moyuanbomo/article/details/123378825

这里说几个需要注意的:

1 搭建好的harbor仓库在创建项目时一定要选择公开的,否则还需要在额外设置k8s。

2 k8s中的每台主机都要修改daemon.json然后依次登录一下harbor仓库。docker login ip:port

3 使用docker pull 拉镜像时需要指定全名例如 docker pull 192.168.180.129:9999/myharbor/myapp:v1

4 所以我们的pod.yaml也要修改为全路径,另外镜像拉去策略也要修改为 IfNotPresent 如果本地不存在则拉去。

apiVersion: v1 kind: Pod metadata:   name: poddemo1   labels:     k1: v1 spec:   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       ports:         - name: tomcatport           containerPort: 8080

重启策略

创建一个pod,仅仅使用一个ubuntu基础镜像,启动后执行 echo打印两个字符串,restartPolicy设置为OnFailure此时pod执行完就会结束。

apiVersion: v1 kind: Pod metadata:   name: poddemo1 spec:   restartPolicy: OnFailure #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: myapp01       image: ubuntu:14.04       imagePullPolicy: IfNotPresent       command: ['/bin/echo','aaaaa','bbbbb']    

当我们修改restartPolicy为Always时则会重复启动pod。

apiVersion: v1 kind: Pod metadata:   name: poddemo1 spec:   restartPolicy: Always #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: myapp01       image: ubuntu:14.04       imagePullPolicy: IfNotPresent       command: ['date']    

启动命令

dockerfile的最后一行描述了容器创建后需要启动的命令,现在我们把这一行删掉,转移到pod.yaml中

FROM centos:7   RUN yum install -y vim  WORKDIR /usr/local  RUN mkdir test   COPY dockerdemo.jar /usr/local/test COPY jdk8.tar.gz /usr/local/test  WORKDIR /usr/local/test RUN tar -zxvf jdk8.tar.gz  ENV JAVA_HOME /usr/local/test/jdk1.8.0_333 ENV PATH $JAVA_HOME/bin:$PATH

apiVersion: v1 kind: Pod metadata:   name: poddemo1 spec:   restartPolicy: Never   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]

除此之外还可以设置args作为command的参数。

apiVersion: v1 kind: Pod metadata:   name: poddemo1 spec:   restartPolicy: Always #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: myapp01       image: ubuntu:14.04       imagePullPolicy: IfNotPresent       command: ['/bin/echo']           args: ['aaa','bbb','cccc']

command和args两个参数对应docker中的ENTRYPOINT和CMD对应。两者之间有互斥的关系,具体如下。

pod基本命令

创建pod:kubectl create -f xxx.yaml

查询全部pod:kubectl get pod

name:pod名称。 ready:pod的准备状态,左边数字是pod中就绪容器的总数目,右边是应有容器。status:pod的状态。restarts:pod的重启次数。age:pod的运行时间。

查询单个pod:kubectl get pod podname

[root@k8s-master1 home]# kubectl get pod poddemo1 NAME       READY   STATUS    RESTARTS   AGE poddemo1   1/1     Running   0          10m

查询pod完整信息:kubectl get pod podname –output json

{     "apiVersion": "v1",     "kind": "Pod",     "metadata": {         "creationTimestamp": "2022-08-17T14:19:12Z",         "name": "poddemo1",         "namespace": "default",         "resourceVersion": "44895",         "selfLink": "/api/v1/namespaces/default/pods/poddemo1",         "uid": "36a6fef7-38bb-46db-afc2-e8ee66cc1b49"     },     "spec": {         "containers": [             {                 "command": [                     "nohup",                     "java",                     "-jar",                     "/usr/local/test/dockerdemo.jar",                     "/u0026"                 ],                 "image": "192.168.239.134:9999/myharbor/myapp:v1",                 "imagePullPolicy": "IfNotPresent",                 "name": "myapp01",                 "ports": [                     {                         "containerPort": 8080,                         "name": "tomcatport",                         "protocol": "TCP"                     }                 ],                 "resources": {},                 "terminationMessagePath": "/dev/termination-log",                 "terminationMessagePolicy": "File",                 "volumeMounts": [                     {                         "mountPath": "/var/run/secrets/kubernetes.io/serviceaccount",                         "name": "default-token-zlxv7",                         "readOnly": true                     }                 ]             }         ],         "dnsPolicy": "ClusterFirst",         "enableServiceLinks": true,         "nodeName": "k8s-node1",         "priority": 0,         "restartPolicy": "Never",         "schedulerName": "default-scheduler",         "securityContext": {},         "serviceAccount": "default",         "serviceAccountName": "default",         "terminationGracePeriodSeconds": 30,         "tolerations": [             {                 "effect": "NoExecute",                 "key": "node.kubernetes.io/not-ready",                 "operator": "Exists",                 "tolerationSeconds": 300             },             {                 "effect": "NoExecute",                 "key": "node.kubernetes.io/unreachable",                 "operator": "Exists",                 "tolerationSeconds": 300             }         ],         "volumes": [             {                 "name": "default-token-zlxv7",                 "secret": {                     "defaultMode": 420,                     "secretName": "default-token-zlxv7"                 }             }         ]     },     "status": {         "conditions": [             {                 "lastProbeTime": null,                 "lastTransitionTime": "2022-08-17T14:19:12Z",                 "status": "True",                 "type": "Initialized"             },             {                 "lastProbeTime": null,                 "lastTransitionTime": "2022-08-17T14:19:16Z",                 "status": "True",                 "type": "Ready"             },             {                 "lastProbeTime": null,                 "lastTransitionTime": "2022-08-17T14:19:16Z",                 "status": "True",                 "type": "ContainersReady"             },             {                 "lastProbeTime": null,                 "lastTransitionTime": "2022-08-17T14:19:12Z",                 "status": "True",                 "type": "PodScheduled"             }         ],         "containerStatuses": [             {                 "containerID": "docker://bcd1cdfbbabe194f8574af00672eac2a4e1408245506bb9aa7f4c4b52c613e7e",                 "image": "192.168.239.134:9999/myharbor/myapp:v1",                 "imageID": "docker-pullable://192.168.239.134:9999/myharbor/myapp@sha256:4e6502311b5cd07f3ed6f55d616ff5c0205e441533541bbd91464965dd725929",                 "lastState": {},                 "name": "myapp01",                 "ready": true,                 "restartCount": 0,                 "state": {                     "running": {                         "startedAt": "2022-08-17T14:19:15Z"                     }                 }             }         ],         "hostIP": "192.168.239.135",         "phase": "Running",         "podIP": "10.244.1.19",         "qosClass": "BestEffort",         "startTime": "2022-08-17T14:19:12Z"     } }

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查看pod状态和生命周期事件:kubectl describe pod podname

Name:         poddemo1 Namespace:    default Priority:     0 Node:         k8s-node1/192.168.239.135 Start Time:   Wed, 17 Aug 2022 22:19:12 +0800 Labels:       <none> Annotations:  <none> Status:       Running IP:           10.244.1.19 Containers:   myapp01:     Container ID:  docker://bcd1cdfbbabe194f8574af00672eac2a4e1408245506bb9aa7f4c4b52c613e7e     Image:         192.168.239.134:9999/myharbor/myapp:v1     Image ID:      docker-pullable://192.168.239.134:9999/myharbor/myapp@sha256:4e6502311b5cd07f3ed6f55d616ff5c0205e441533541bbd91464965dd725929     Port:          8080/TCP     Host Port:     0/TCP     Command:       nohup       java       -jar       /usr/local/test/dockerdemo.jar       &     State:          Running       Started:      Wed, 17 Aug 2022 22:19:15 +0800     Ready:          True     Restart Count:  0     Environment:    <none>     Mounts:       /var/run/secrets/kubernetes.io/serviceaccount from default-token-zlxv7 (ro) Conditions:   Type              Status   Initialized       True    Ready             True    ContainersReady   True    PodScheduled      True  Volumes:   default-token-zlxv7:     Type:        Secret (a volume populated by a Secret)     SecretName:  default-token-zlxv7     Optional:    false QoS Class:       BestEffort Node-Selectors:  <none> Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s                  node.kubernetes.io/unreachable:NoExecute for 300s Events:   Type    Reason     Age   From                Message   ----    ------     ----  ----                -------   Normal  Scheduled  14m   default-scheduler   Successfully assigned default/poddemo1 to k8s-node1   Normal  Pulled     14m   kubelet, k8s-node1  Container image "192.168.239.134:9999/myharbor/myapp:v1" already present on machine   Normal  Created    14m   kubelet, k8s-node1  Created container myapp01   Normal  Started    14m   kubelet, k8s-node1  Started container myapp01

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删除pod:kubectl delete pod podname

删除全部pod:kubectl delete pod all

设置环境变量

创建pod后进入pod中的容器内部,查看环境变量是否生效。

kubectl –namespace=default exec -it poddemo1 –container myapp01 — sh

apiVersion: v1 kind: Pod metadata:   name: poddemo1 spec:   restartPolicy: Never   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       env:         - name: aaaaa           value: 'ttttttt'       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]

设置的环境变量还可以获取pod的信息

apiVersion: v1 kind: Pod metadata:   name: poddemo5 spec:   restartPolicy: Never   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       env:         - name: aaaaa           value: 'ttttttt'         - name: nodename           valueFrom:              fieldRef:               fieldPath: metadata.name         - name: nodenamespace           valueFrom:              fieldRef:               fieldPath: metadata.namespace             ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]

数据持久化和共享-hostPath

hostPath将宿主机的某个目录映射到容器内的目录,容器终止后,宿主机上将保留目录,以及容器内操控的文件。

apiVersion: v1 kind: Pod metadata:   name: poddemo6 spec:   restartPolicy: OnFailure #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: writepod #容器1       image: ubuntu:14.04       imagePullPolicy: IfNotPresent       command: ["bash","-c","echo /"aaaaaaa/" >> /data/hello.txt"] # 向容器内的/data/hello.txt写入数据       volumeMounts:         - name: data1 #对应挂载卷唯一名称           mountPath: /data #映射到容器内的目录     - name: readpod #容器2       image: ubuntu:14.04       imagePullPolicy: IfNotPresent       command: ["bash","-c","sleep 10; cat /data/hello.txt"] # 向容器内的/data/hello.txt 读取数据       volumeMounts:         - name: data1 #对应挂载卷唯一名称           mountPath: /data #映射到容器内的目录   volumes: # 宿主机挂载     - name: data1 # 挂载卷唯一名称       hostPath: #类型,其实还有其他的类型,hostPath只是其中一个         path: /home # 容器内部挂载到的宿主机目录

虽然容器停止了,但是在node上是可以看到写入的文件的

看以下配置两个容器的mountPath并没有在同一个目录下,但是依然可以取到文件,这表示最终能让容器间操作同一个目录的地方是 volumeMount.name与volume.name对应。

apiVersion: v1 kind: Pod metadata:   name: poddemo6 spec:   restartPolicy: OnFailure #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: writepod #容器1       image: ubuntu:14.04       imagePullPolicy: IfNotPresent       command: ["bash","-c","echo /"aaaaaaa/" >> /data/hello.txt"] # 向容器内的/data/hello.txt写入数据       volumeMounts:         - name: data1 #对应挂载卷唯一名称           mountPath: /data #映射到容器内的目录     - name: readpod #容器2       image: ubuntu:14.04       imagePullPolicy: IfNotPresent       command: ["bash","-c","sleep 10; cat /tmp/hello.txt"] # 向容器内的/tmp/hello.txt 读取数据       volumeMounts:         - name: data1 #对应挂载卷唯一名称           mountPath: /tmp #映射到容器内的目录   volumes: # 宿主机挂载     - name: data1 # 挂载卷唯一名称       hostPath: #类型,其实还有其他的类型,hostPath只是其中一个         path: /home # 容器内部挂载到的宿主机目录

数据持久化和共享-emptyDir

将数据临时写入磁盘,当pod停止后卷数据不会保留。

apiVersion: v1 kind: Pod metadata:   name: poddemo8 spec:   restartPolicy: OnFailure #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: writepod #容器1       image: ubuntu:14.04       imagePullPolicy: IfNotPresent       command: ["bash","-c","echo /"aaaaaaa/" >> /data/hello.txt"] # 向容器内的/data/hello.txt写入数据       volumeMounts:         - name: data1 #对应挂载卷唯一名称           mountPath: /data #映射到容器内的目录     - name: readpod #容器2       image: ubuntu:14.04       imagePullPolicy: IfNotPresent       command: ["bash","-c","sleep 10; cat /data/hello.txt"] # 向容器内的/data/hello.txt 读取数据       volumeMounts:         - name: data1 #对应挂载卷唯一名称           mountPath: /data #映射到容器内的目录   volumes: # 宿主机挂载     - name: data1 # 挂载卷唯一名称       emptyDir: #类型,其实还有其他的类型,emptyDir只是其中一个

JSON格式编写pod文件

{   "apiVersion": "v1",   "kind": "Pod",   "metadata": {     "name": "poddemo7"   },   "spec": {     "restartPolicy": "OnFailure",     "containers": [       {         "name": "myapp01",         "image": "ubuntu:14.04",         "imagePullPolicy": "IfNotPresent",         "command": [           "/bin/echo",           "aaaaa",           "bbbbb"         ]       }     ]   } }

ConfigMap

configMap供容器使用的典型方法为:1 生成容器内的环境变量。 2 设置容器启动命令的启动参数(需要设置为环境变量)。3 以Volume的形式挂载为容器内的文件或目录。

使用yaml的方式创建ConfigMap,定义了两个key,value。

apiVersion: v1 kind: ConfigMap metadata:   name: configmap1 data:   key1: value1   key2: value2

通过环境变量的方式使用ConfigMap,先创建configmap设置两个key,value,然后再pod中通过configMapKeyRef引用,这种引用方式环境变量的名称是env.name。

apiVersion: v1 kind: ConfigMap metadata:   name: configmap1 data:   key1: value1   key2: value2 --- apiVersion: v1 kind: Pod metadata:   name: poddemo5 spec:   restartPolicy: Never   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       env:         - name: aaaaa #定义环境变量           value: 'ttttttt'         - name: nodename #获取pod属性作为环境变量           valueFrom:             fieldRef:               fieldPath: metadata.name         - name: ccccccc           valueFrom:             configMapKeyRef:               name: configmap1               key: key1         - name: ddddddd           valueFrom:             configMapKeyRef:               name: configmap1               key: key2       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]

使用containers.envFrom可以直接将一个ConfigMap中定义的属性全部映射到环境变量中。

apiVersion: v1 kind: ConfigMap metadata:   name: configmap2 data:   key1: value1   key2: value2 --- apiVersion: v1 kind: Pod metadata:   name: poddemo10 spec:   restartPolicy: Never   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       env:         - name: aaaaa #定义环境变量           value: 'ttttttt'         - name: nodename #获取pod属性作为环境变量           valueFrom:             fieldRef:               fieldPath: metadata.name       envFrom:       - configMapRef:           name: configmap2       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]

下面这种配置,在启动参数中使用环境变量,而环境变量是在configmap中声明的。

apiVersion: v1 kind: ConfigMap metadata:   name: configmap2 data:   key1: value1   key2: value2 --- apiVersion: v1 kind: Pod metadata:   name: poddemo11 spec:   restartPolicy: OnFailure #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: myapp01       image: ubuntu:14.04       imagePullPolicy: IfNotPresent       command: ['/bin/sh','-c']           args: ["echo ${aaa} ${key1} ${key2}"]       env:         - name: aaa           value: ttttttt       envFrom:       - configMapRef:           name: configmap2     

将configmap映射到容器内部的文件中。

apiVersion: v1 kind: ConfigMap metadata:   name: configmap3 data:   key1: '我是一只小青蛙'   key2: '呱呱呱 呱呱呱' --- apiVersion: v1 kind: Pod metadata:   name: poddemo12 spec:   restartPolicy: Never   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]       volumeMounts:       - name: config         mountPath: /home   volumes:   - name: config     configMap:       name: configmap3       items:       - key: key1         path: file1       - key: key2         path: file2

如何在应用configmap时不指定item则会给configmap中的每个key生成一个对应的文件。

apiVersion: v1 kind: ConfigMap metadata:   name: configmap4 data:   key1: '我是一只小青蛙'   key2: '呱呱呱 呱呱呱' --- apiVersion: v1 kind: Pod metadata:   name: poddemo13 spec:   restartPolicy: Never   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]       volumeMounts:       - name: config         mountPath: /home   volumes:   - name: config     configMap:       name: configmap4

pod共享宿主机网络

pod中所有容器网络都是共享的,一个pod中所有的容器中的网络都是一致的,他们能够互相通过localhost访问彼此。默认的每个pod都有属于自己的podip,k8s集群内可以访问任意podip但外网无法访问

podip。但也可以直接设置pod为Host网络模式,这样pod中的所有容器将会直接暴露到外部系统。通过spec.hostNetwork设置。

apiVersion: v1 kind: Pod metadata:   name: poddemo14 spec:   restartPolicy: Never   hostNetwork: true   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]

直接将pod映射到Host最大的弊端是,如果同时启动多个容器,且容器内的端口一致,则只有一个会启动成功,剩下则会报以下错误。

Warning  FailedScheduling  35s (x2 over 35s)  default-scheduler  0/2 nodes are available: 1 node(s) didn't have free ports for the requested pod ports, 1 node(s) had taints that the pod didn't tolerate.

pod的生命周期

pod的生命周期可以简单描述为:首先pod被创建,紧接着pod被调度到Node进行部署运行。Pod是非常忠诚的,一旦被分配到Node后,就不会离开这个Node

直到它被删除,生命周期完结。

pod的生命周期也就是pod的状态值

pending:API Server 已经创建该Pod,但在Pod内还有一个或多个容器的镜像没有创建,包括正在下载镜像的过程。

running:pod内所有的容器均已创建,且至少有一个容器处于运行状态,正在启动状态或正在重启状态。

succeeded:pod内所有容器均成功退出,且不会重启。

failed:pod内容器均已退出,但至少有一个容器为退出失败状态。

unknown:由于某种原因无法获取该pod的状态,可能由于网络通信不畅通导致。

pod的生命周期函数

pod中的容器有两个生命周期函数,一个在容器创建成功后,一个在终止前。可选的操作有执行命令行或者发送http请求。下边实例在创建容器后复制容器内的jar包,终止容器后发送一个get请求,地址是我本地启动的一个项目。

apiVersion: v1 kind: Pod metadata:   name: poddemo17 spec:   restartPolicy: OnFailure #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]       lifecycle: #声明周期钩子函数         postStart: #容器创建成功后,调用该回调函数           exec: #回调有两种做法 exec 和 http             command:               - "cp"               - "/usr/local/test/dockerdemo.jar"               - "copyapp"         preStop: #在容器被终止前调用该回调函数           httpGet:             host: 192.168.0.100             path: /test             port: 8080             scheme: HTTP

通过环境变量获取pod和container的信息

需要注意获取pod信息和container信息使用的方式不同。

apiVersion: v1 kind: Pod metadata:   name: poddemo18   labels:     labels1: labls111     labels2: labls222   annotations:     anno1: anno11     anno2: anno22 spec:   restartPolicy: OnFailure #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]       env:         - name: aaa           valueFrom:             fieldRef:               fieldPath: metadata.name # pod名称         - name: bbb           valueFrom:             fieldRef:               fieldPath: metadata.namespace # pod所在的命名空间名称              - name: ccc           valueFrom:             fieldRef:               fieldPath: metadata.uid # pod的UID           - name: ddd           valueFrom:             fieldRef:               fieldPath: metadata.labels['labels1'] # pod的label          - name: eee           valueFrom:             fieldRef:               fieldPath: metadata.labels['labels2'] # pod的label            - name: fff           valueFrom:             fieldRef:               fieldPath: metadata.annotations['anno1'] # pod的annotation          - name: ggg           valueFrom:             fieldRef:               fieldPath: metadata.annotations['anno2'] # pod的annotation             - name: hhh           valueFrom:             fieldRef:               fieldPath: status.podIP # pod的IP地址          - name: iii           valueFrom:             fieldRef:               fieldPath: spec.serviceAccountName # pod使用的serviceAccount名称            - name: jjj           valueFrom:             fieldRef:               fieldPath: spec.nodeName # pod所在node的名称         - name: kkk           valueFrom:             fieldRef:               fieldPath: status.hostIP # pod所在node的ip地址                 - name: AAA #以下为容器内的信息           valueFrom:             resourceFieldRef:               containerName: myapp01               resource: requests.cpu #CPU Request         - name: BBB           valueFrom:             resourceFieldRef:               containerName: myapp01               resource: limits.cpu #CPU Limit         - name: CCC           valueFrom:             resourceFieldRef:               containerName: myapp01               resource: requests.memory # Memory Request         - name: DDD           valueFrom:             resourceFieldRef:               containerName: myapp01               resource: limits.memory   # MemoryLimit   

通过文件挂载获取pod和container的信息

需要注意获取pod信息和container信息使用的方式不同。

apiVersion: v1 kind: Pod metadata:   name: poddemo19   labels:     labels1: labls111     labels2: labls222   annotations:     anno1: anno11     anno2: anno22 spec:   restartPolicy: OnFailure #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]       volumeMounts:         - name: podinfo           mountPath: /home   volumes:     - name: podinfo       downwardAPI:         items:           - path: "aaa"             fieldRef:               fieldPath: metadata.name           - path: "bbb"             fieldRef:               fieldPath: metadata.namespace             - path: "ccc"             fieldRef:               fieldPath: metadata.uid           - path: "ddd"             fieldRef:               fieldPath: metadata.labels['labels1']           - path: "eee"             fieldRef:               fieldPath: metadata.labels['labels2']               - path: "fff"             fieldRef:               fieldPath: metadata.annotations['anno1']               - path: "ggg"             fieldRef:               fieldPath: metadata.annotations['anno2']           - path: "AAA"             resourceFieldRef:               containerName: myapp01               resource: requests.cpu           - path: "BBB"             resourceFieldRef:               containerName: myapp01               resource: limits.cpu           - path: "CCC"             resourceFieldRef:               containerName: myapp01               resource: requests.memory               - path: "DDD"             resourceFieldRef:               containerName: myapp01               resource: limits.memory                                                                

健康检查和服务可用性检查

LivenessProbe探针:用于判断容器是否存活(running状态),如果LivenessProbe探针探测到容器不健康,则kubectl将杀掉该容器,并根据容器的重启策略做相应的处理。如果一个容器不包含LivenessProbe探针

那么kubelet认为该容器的LivenessProbe探针返回的值永远是Success。

ReadinessProbe探针:用于判断容器服务是否可用(Ready状态),达到Ready状态的pod才可以接收请求。对于被Service管理的pod,service与Pod Endpoint的关联关系也将基于Pod是否Ready进行设置。

如果在运行过程中Ready状态变成FALSE,则系统自动将其从Service的后端Endpoint列表中隔离出去,后续再把回复到Ready状态的Pod加回到后端Endpoint列表。这样保证客户端在访问Service时不回被转发

到服务不可用的Pod实例上。

apiVersion: v1 kind: Pod metadata:   name: poddemo20 spec:   restartPolicy: OnFailure #Always 表示pod一旦停止就会立刻重启 OnFailure 表示容器正常退出不重启,正常退出码是0,Never 表示发送退出报告给master但是不重启   containers:     - name: myapp01       image: 192.168.180.129:9999/myharbor/myapp:v1       imagePullPolicy: IfNotPresent       ports:         - name: tomcatport           containerPort: 8080       command: ["nohup","java","-jar","/usr/local/test/dockerdemo.jar","&"]       livenessProbe:         httpGet:           host: 192.168.43.4           path: /test1           port: 8080           scheme: HTTP         initialDelaySeconds: 5 #启动活动或准备就绪探测之前容器启动后的秒数         periodSeconds: 3 #执行探测的频率(以秒为单位)。默认为10秒。最小值为1。         timeoutSeconds: 2 #探测超时的秒数。默认为1秒。最小值为1         failureThreshold: 3 #在存活探针重新启动容器之前允许探针失败的次数(或就绪探针将pod标记为不可用)。         successThreshold: 1 #探针在开始失败后必须报告成功的次数,以便重置探测过程。       readinessProbe:         httpGet:           host: 192.168.43.4           path: /test2           port: 8080           scheme: HTTP         initialDelaySeconds: 5         periodSeconds: 3         timeoutSeconds: 2         failureThreshold: 3         successThreshold: 1 

两种探针都支持三种检测方式。

ExecAction:在容器中执行指定的命令进行检测,当命令执行成功(返回码为0),检测成功。

exec:   command:   - cat   - /tmp/health

TCPSocketAction:对于容器中的指定TCP端口进行检测,当TCP端口被占用,检测成功。

tcpSocket:   port: 8080

HTTPGetAction:发生一个HTTP请求,当返回码介于200-400之间,检测成功。

httpGet:   path: /healthz   port: 8080

 

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