Kubernetes-Pod
概念
在k8s中我们不会直接操作容器，而是把容器包装成Pod在进行管理运行于Node节点上，若干相关容器的组合。Pod内包含的容器运行在同一宿主机上，使用相同的网络命令空间
、ip地址和端口，能够通过localhost进行通信。Pod是k8s进行创建、调度和管理的最小单位，他提供了比容器更高层次的抽象、使得部署和管理更加灵活。一个Pod可以包含一个容器或多个容器。
发布第一个容器化应用
1、有镜像
2、部署应用。
--考虑做不做副本
不做副本就是pod
做副本以deployment/RC/DaemonSet方式去创建
--做了副本访问还需要做一个service，使用访问。
创建Pod
参考文档
https://kubernetes.io/zh-cn/docs/concepts/workloads/pods/
使用yaml方式创建
[root@kubernetes-master study]# cat pod-nginx.yaml
---
apiVersion: v1 #api版本
kind: Pod #创建的资源对象为pod
metadata: #元数据
name: my-nginx #pod的名字
spec: #属性
containers: #定义容器
- name: my-nginx-web #容器名
image: daocloud.io/library/nginx #镜像 我这里用的daocloud的镜像
ports: #端口
- containerPort: 80 #容器暴漏端口
查看Pod信息
# 查看pod信息
[root@kubernetes-master study]# kubectl get pod
NAME READY STATUS RESTARTS AGE
my-nginx 1/1 Running 0 4m5s
# 查看详情pod信息
[root@kubernetes-master study]# kubectl get pod -o wide
# 查看pod创建详细信息
[root@kubernetes-master study]# kubectl describe pod my-nginx
Name: my-nginx
Namespace: default
Priority: 0
Service Account: default
Node: kubernetes-node1/10.10.10.22
Start Time: Tue, 07 Nov 2023 11:18:45 +0800
Labels: <none>
Annotations: cni.projectcalico.org/containerID: 89f8c7ab53802b66299950e163f2c3258809dc0e238efc6ee7c02df2587df857
cni.projectcalico.org/podIP: 10.10.20.230/32
cni.projectcalico.org/podIPs: 10.10.20.230/32
Status: Running
IP: 10.10.20.230
IPs:
IP: 10.10.20.230
Containers:
my-nginx-web:
Container ID: docker://c56dd1464b60fd9bd7e1545553461adf38a243800a01cad0c366fd25687eb5e4
Image: daocloud.io/library/nginx
Image ID: docker-pullable://daocloud.io/library/nginx@sha256:1a53eb723d17523512bd25c27299046cfa034cce309f4ed330c943a304513f59
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Tue, 07 Nov 2023 11:18:47 +0800
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-tdpfn (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-tdpfn:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 4m48s default-scheduler Successfully assigned default/my-nginx to kubernetes-node1
Normal Pulling 4m47s kubelet Pulling image "daocloud.io/library/nginx"
Normal Pulled 4m46s kubelet Successfully pulled image "daocloud.io/library/nginx" in 529.869685ms (529.888256ms including waiting)
Normal Created 4m46s kubelet Created container my-nginx-web
Normal Started 4m46s kubelet Started container my-nginx-web
访问测试
# 访问podip
[root@kubernetes-master study]# curl 10.10.20.230
进入pod
# 进入pod容器中
[root@kubernetes-master study]# kubectl exec -it my-nginx sh
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
# 查看nginx默认发布目录下文件
# ls /usr/share/nginx/html/
50x.html index.html
删除pod
[root@kubernetes-master study]# kubectl delete -f pod-nginx.yaml
pod "my-nginx" deleted
使用命令方式生成yaml
# 生成yaml
kubectl run my-nginx-2 --image=daocloud.io/library/nginx --restart=Never --dry-run=client -o yaml > my-nginx-2.yaml
# 创建pod
[root@kubernetes-master study]# kubectl apply -f pod-nginx-2.yaml
pod/my-nginx-2 created
# 查看pod
[root@kubernetes-master study]# kubectl get pod
NAME READY STATUS RESTARTS AGE
my-nginx-2 1/1 Running 0 9s
# 查看详细信息
[root@kubernetes-master study]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
my-nginx-2 1/1 Running 0 17s 10.10.20.232 kubernetes-node1 <none> <none>
# 测试访问podip
[root@kubernetes-master study]# curl 10.10.20.232
<!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>
# 删除pod
[root@kubernetes-master study]# kubectl delete -f pod-nginx-2.yaml
pod "my-nginx-2" deleted
Pod的状态详解
CrashLoopBackOff： 容器退出，kubelet正在将它重启
InvalidImageName： 无法解析镜像名称
ImageInspectError： 无法校验镜像
ErrImageNeverPull： 策略禁止拉取镜像
ImagePullBackOff： 正在重试拉取
RegistryUnavailable： 连接不到镜像中心
ErrImagePull： 通用的拉取镜像出错
CreateContainerConfigError： 不能创建kubelet使用的容器配置
CreateContainerError： 创建容器失败
m.internalLifecycle.PreStartContainer 执行hook报错
RunContainerError： 启动容器失败
PostStartHookError： 执行hook报错
ContainersNotInitialized： 容器没有初始化完毕
ContainersNotReady： 容器没有准备完毕
ContainerCreating：容器创建中
PodInitializing：pod 初始化中
DockerDaemonNotReady：docker还没有完全启动
NetworkPluginNotReady： 网络插件还没有完全启动
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