一 pod简介
1.1 介绍
- Pod是K8s集群中所有业务类型的基础
- Pod是在K8s集群中运行部署应用或服务的最小单元,它是可以支持多容器的。
- Pod的设计理念是支持多个容器在一个Pod中共享网络地址和文件系统
pod和容器的区别就是,一个pod可以有多个容器,当一个pod只有一个容器的时候,访问pod就是访问容器,对于一个kubernets来说,一个pods至少有两个容器,一个是不可见的,称为pause容器,另一个就是业务容器
pod是一个逻辑概念,pod中的一个容器异常,整个pod重新创建
- Kubernetes为每个Pod都分配了唯一的IP地址,称之为PodIP,一个Pod里的多个容器共享PodIP地址。要求底层网络支持集群内任意两个Pod之间的直接通信,通常采用虚拟二层网络技术来实现(Flannel)。
- POD可以与其它主机上的POD直接通讯。
- 如果有POD意外停止,K8S会根据资源设定重启或创建POD,直到符合预期设定值
- pause容器劫持业务容器的所有流量,IP是配置在pause容器的,在创建pod的时候,自动创建,用来接管容器网络
1.2 pod的一个应用场景
- pod含有两个容器,File Puller先于web server容器启动
- 拉取代码放到volume中,然后自毁
- web server容器启动,读物volume的代码,用于用户访问
二 POD简单操作
2.1 创建一个关于nginx的pods
[[email protected] namespace]# cd ../
[[email protected] yamls]# mkdir pods
[[email protected] yamls]# cd pods
[[email protected] pods]# vi nginx-pods.yaml
apiVersion: v1 kind: Pod metadata: name: nginx labels: app: nginx annotations: test: this is a test app spec: #资源描述信息 containers: - name: nginx image: nginx ports: - containerPort: 80
这是一个最简单的pods,只是运行一个nginx的业务,没有任何其他的东西
[[email protected] pods]# kubectl apply -f nginx-pods.yaml
由于没有指定ns,所以pods运行在defaults中,查看
[[email protected] pods]# kubectl get pods
NAME READY STATUS RESTARTS AGE nginx 1/1 Running 0 85s
1/1:后面的1表示这个pods运行了几个容器,前面的1表示几个容器处于redy状态
查看容器
[[email protected] pods]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nginx 1/1 Running 0 6m41s 10.244.2.6 192.168.132.133 <none> <none>
访问
[[email protected] pods]# curl http://10.244.2.6
<!DOCTYPE html> <html> <head> <title>Welcome to nginx!</title> <style> 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>
2.2 配置映射端口
[[email protected] pods]# vim nginx-pods.yaml
apiVersion: v1 kind: Pod metadata: name: nginx labels: app: nginx spec: hostNetwork: true containers: - name: nginx image: nginx ports: - containerPort: 80
[[email protected] pods]# kubectl delete -f nginx-pods.yaml
[[email protected] pods]# kubectl create -f nginx-pods.yaml
[[email protected] pods]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nginx 0/1 ContainerCreating 0 4s 192.168.132.133 192.168.132.133 <none> <none>
[[email protected] pods]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nginx 1/1 Running 0 95s 192.168.132.133 192.168.132.133 <none> <none>
2.3 pod常用配置
name: string image: string imagePullPolicy: [Always |Never | IfNotPresent] #拉取镜像策略,默认是第三种,先看本地,本地没有,才拉取 restartPolicy: [Always | Never | OnFailure] command: [string] args: [string] ports: containerPort: int hostPort: int protocol: string env: name: string value: string hostNetwork: bool resources volumes livenessProbe ReadnessProbe
2.4 配置其他策略
运行多个容器,并使用拉取镜像策略
[[email protected] pods]# vim nginx-pods.yaml
apiVersion: v1 kind: Pod metadata: name: nginx labels: app: nginx annotations: test: this is a test app spec: imagePullPolicy: Always restartPolicy: Always containers: - name: nginx image: nginx ports: - containerPort: 80 hostPost: 8080 env: - name: test value: aaa - name: test1 value: bbb - name: busybox image: busybox command: - sh - -c - sleep 3600
2.4 删除再创建pod
[[email protected] pods]# kubectl delete pod nginx
[[email protected] pods]# kubectl create -f nginx-pods.yaml
error: error validating "nginx-pods.yaml": error validating data: ValidationError(Pod.spec): unknown field "imagePullPolicy" in io.k8s.api.core.v1.PodSpec; if you choose to ignore these errors, turn validation off with --validate=false
imagePullPolicy这个不能指定所有容器
[[email protected] pods]# vim nginx-pods.yaml
apiVersion: v1 kind: Pod metadata: name: nginx labels: app: nginx annotations: test: this is a test app spec: restartPolicy: Always containers: - name: nginx image: nginx imagePullPolicy: Always ports: - containerPort: 80 hostPort: 8080 env: - name: test value: aaa - name: test1 value: bbb - name: busybox image: busybox command: - sh - -c - sleep 3600
[[email protected] pods]# kubectl create -f nginx-pods.yaml
[[email protected] pods]# kubectl get pods
NAME READY STATUS RESTARTS AGE nginx 2/2 Running 0 28s
[[email protected] pods]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nginx 2/2 Running 0 36s 10.244.2.7 192.168.132.133 <none> <none>
做了端口映射,两种方式访问
[[email protected] pods]# curl http://192.168.132.133:8080
[[email protected] pods]# curl http://10.244.2.7
2.5 查看pods的详细信息
[[email protected] pods]# kubectl describe po nginx
Name: nginx Namespace: default Priority: 0 Node: 192.168.132.133/192.168.132.133 Start Time: Thu, 09 Jan 2020 18:17:48 -0500 Labels: app=nginx Annotations: test: this is a test app Status: Running IP: 10.244.2.7 IPs: IP: 10.244.2.7 Containers: nginx: Container ID: docker://676a2d9bebda40d86138190093d1a6d6cf6f16e5ff0e89fc22df53a74bdf8048 Image: nginx Image ID: docker-pullable://[email protected]:8aa7f6a9585d908a63e5e418dc5d14ae7467d2e36e1ab4f0d8f9d059a3d071ce Port: 80/TCP Host Port: 8080/TCP State: Running Started: Thu, 09 Jan 2020 18:17:55 -0500 Ready: True Restart Count: 0 Environment: test: aaa test1: bbb Mounts: /var/run/secrets/kubernetes.io/serviceaccount from default-token-bwbrn (ro) busybox: Container ID: docker://e8cc006f3ab292701d9876d84881af90f4c97ea22f32bf0cabf2b93d82b8c82b Image: busybox Image ID: docker-pullable://[email protected]:6915be4043561d64e0ab0f8f098dc2ac48e077fe23f488ac24b665166898115a Port: <none> Host Port: <none> Command: sh -c sleep 3600 State: Running Started: Thu, 09 Jan 2020 18:18:00 -0500 Ready: True Restart Count: 0 Environment: <none> Mounts: /var/run/secrets/kubernetes.io/serviceaccount from default-token-bwbrn (ro) Conditions: Type Status Initialized True Ready True ContainersReady True PodScheduled True Volumes: default-token-bwbrn: Type: Secret (a volume populated by a Secret) SecretName: default-token-bwbrn 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 Pulling 4m43s kubelet, 192.168.132.133 Pulling image "nginx" Normal Scheduled 4m41s default-scheduler Successfully assigned default/nginx to 192.168.132.133 Normal Pulled 4m38s kubelet, 192.168.132.133 Successfully pulled image "nginx" Normal Created 4m37s kubelet, 192.168.132.133 Created container nginx Normal Started 4m37s kubelet, 192.168.132.133 Started container nginx Normal Pulling 4m37s kubelet, 192.168.132.133 Pulling image "busybox" Normal Pulled 4m32s kubelet, 192.168.132.133 Successfully pulled image "busybox" Normal Created 4m32s kubelet, 192.168.132.133 Created container busybox Normal Started 4m32s kubelet, 192.168.132.133 Started container busybox
三 yaml文件找回
如果不小心删除了yaml文件,可以通过描述信息找回
3.1 删除yaml文件
[[email protected] pods]# rm -rf nginx-pods.yaml
[[email protected] pods]# kubectl get pods nginx -o yaml
apiVersion: v1 kind: Pod metadata: annotations: test: this is a test app creationTimestamp: "2020-01-09T23:17:51Z" labels: app: nginx name: nginx namespace: default resourceVersion: "43864" selfLink: /api/v1/namespaces/default/pods/nginx uid: 41510342-de97-4b37-ab95-0a01dd73aac7 spec: containers: - env: - name: test value: aaa - name: test1 value: bbb image: nginx imagePullPolicy: Always name: nginx ports: - containerPort: 80 hostPort: 8080 protocol: TCP resources: {} terminationMessagePath: /dev/termination-log terminationMessagePolicy: File volumeMounts: - mountPath: /var/run/secrets/kubernetes.io/serviceaccount name: default-token-bwbrn readOnly: true - command: - sh - -c - sleep 3600 image: busybox imagePullPolicy: Always name: busybox resources: {} terminationMessagePath: /dev/termination-log terminationMessagePolicy: File volumeMounts: - mountPath: /var/run/secrets/kubernetes.io/serviceaccount name: default-token-bwbrn readOnly: true dnsPolicy: ClusterFirst enableServiceLinks: true nodeName: 192.168.132.133 priority: 0 restartPolicy: Always 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-bwbrn secret: defaultMode: 420 secretName: default-token-bwbrn status: conditions: - lastProbeTime: null lastTransitionTime: "2020-01-09T23:17:48Z" status: "True" type: Initialized - lastProbeTime: null lastTransitionTime: "2020-01-09T23:18:01Z" status: "True" type: Ready - lastProbeTime: null lastTransitionTime: "2020-01-09T23:18:01Z" status: "True" type: ContainersReady - lastProbeTime: null lastTransitionTime: "2020-01-09T23:17:51Z" status: "True" type: PodScheduled containerStatuses: - containerID: docker://e8cc006f3ab292701d9876d84881af90f4c97ea22f32bf0cabf2b93d82b8c82b image: busybox:latest imageID: docker-pullable://[email protected]:6915be4043561d64e0ab0f8f098dc2ac48e077fe23f488ac24b665166898115a lastState: {} name: busybox ready: true restartCount: 0 started: true state: running: startedAt: "2020-01-09T23:18:00Z" - containerID: docker://676a2d9bebda40d86138190093d1a6d6cf6f16e5ff0e89fc22df53a74bdf8048 image: nginx:latest imageID: docker-pullable://[email protected]:8aa7f6a9585d908a63e5e418dc5d14ae7467d2e36e1ab4f0d8f9d059a3d071ce lastState: {} name: nginx ready: true restartCount: 0 started: true state: running: startedAt: "2020-01-09T23:17:55Z" hostIP: 192.168.132.133 phase: Running podIP: 10.244.2.7 podIPs: - ip: 10.244.2.7 qosClass: BestEffort startTime: "2020-01-09T23:17:48Z"
3.2 使用命令恢复
[[email protected] pods]# kubectl get pods nginx -o yaml > nginx-pods.yaml
删除不必要的信息
[[email protected] pods]# vim nginx-pods.yaml
apiVersion: v1 kind: Pod metadata: annotations: test: this is a test app labels: app: nginx name: nginx namespace: default spec: containers: - env: - name: test value: aaa - name: test1 value: bbb image: nginx imagePullPolicy: Always name: nginx ports: - containerPort: 80 hostPort: 8080 protocol: TCP - command: - sh - -c - sleep 3600 image: busybox imagePullPolicy: Always name: busybox restartPolicy: Always
[[email protected] pods]# kubectl delete pod nginx
[[email protected] pods]# kubectl create -f nginx-pods.yaml
3.3 根据恢复的yaml文件验证
[[email protected] pods]# kubectl get pods
NAME READY STATUS RESTARTS AGE nginx 2/2 Running 0 14s
[[email protected] pods]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nginx 2/2 Running 0 27s 10.244.2.8 192.168.132.133 <none> <none>
[[email protected] pods]# curl http://192.168.132.133:8080
[[email protected] pods]# curl http://10.244.2.8
<!DOCTYPE html> <html> <head> <title>Welcome to nginx!</title> <style> 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>
pod的简单操作学习到这里
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原文地址:https://www.cnblogs.com/zyxnhr/p/12182534.html