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
