004.kubernets对于pod的简单管理
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
[root@docker-server1 namespace]# cd ../
[root@docker-server1 yamls]# mkdir pods
[root@docker-server1 yamls]# cd pods
[root@docker-server1 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
[root@docker-server1 pods]# kubectl apply -f nginx-pods.yaml
由于没有指定ns，所以pods运行在defaults中，查看
[root@docker-server1 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
[root@docker-server1 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
[root@docker-server1 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
[root@docker-server1 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
[root@docker-server1 pods]# kubectl delete -f nginx-pods.yaml
[root@docker-server1 pods]# kubectl create -f nginx-pods.yaml
[root@docker-server1 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>
[root@docker-server1 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
[root@docker-server1 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
[root@docker-server1 pods]# kubectl delete pod nginx
[root@docker-server1 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
[root@docker-server1 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
[root@docker-server1 pods]# kubectl create -f nginx-pods.yaml
[root@docker-server1 pods]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx 2/2 Running 0 28s
[root@docker-server1 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
[root@docker-server1 pods]# curl http://192.168.132.133:8080
[root@docker-server1 pods]# curl http://10.244.2.7
2.5 查看pods的详细信息
[root@docker-server1 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://nginx@sha256:8aa7f6a9585d908a63e5e418dc5d14ae7467d2e36e1ab4f0d8f9d059a3d071ce
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://busybox@sha256:6915be4043561d64e0ab0f8f098dc2ac48e077fe23f488ac24b665166898115a
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
[root@docker-server1 pods]# rm -rf nginx-pods.yaml
[root@docker-server1 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://busybox@sha256:6915be4043561d64e0ab0f8f098dc2ac48e077fe23f488ac24b665166898115a
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://nginx@sha256:8aa7f6a9585d908a63e5e418dc5d14ae7467d2e36e1ab4f0d8f9d059a3d071ce
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
[root@docker-server1 pods]# kubectl get pods nginx -o yaml > nginx-pods.yaml
删除不必要的信息
[root@docker-server1 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
[root@docker-server1 pods]# kubectl delete pod nginx
[root@docker-server1 pods]# kubectl create -f nginx-pods.yaml
3.3 根据恢复的yaml文件验证
[root@docker-server1 pods]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx 2/2 Running 0 14s
[root@docker-server1 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>
[root@docker-server1 pods]# curl http://192.168.132.133:8080
[root@docker-server1 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
博主声明：本文的内容来源主要来自誉天教育晏威老师，由本人实验完成操作验证，需要的博友请联系誉天教育（http://www.yutianedu.com/），获得官方同意或者晏老师（https://www.cnblogs.com/breezey/）本人同意即可转载，谢谢！
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