kubernetes 应用快速入门
增删改查
增
使用kubectl run 来增加一个pod，使用nginx的镜像，开放80端口，副本数为 1
[root@master ~]# kubectl run nginx-deploy --image=nginx:1.14-alpine --port=80 --replicas=1 kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead. deployment.apps/nginx-deploy created
查看
在第一次查看时，因为nginx镜像还需要时间拖拽下来，看到的是还在创建中
[root@master ~]# kubectl get pods NAME READY STATUS RESTARTS AGE nginx-deploy-7689897d8d-hkl8n 0/1 ContainerCreating 0 8s
使用 -o wide 来查看详细信息
[root@master ~]# kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nginx-deploy-7689897d8d-hkl8n 1/1 Running 0 2m37s 10.244.1.2 node01 <none> <none>
当镜像拖拽完成后，pod就被创建成功了。
能看到详细信息中，该pod所对应的容器呗创建在node01 上，并且ip地址是：10.244.1.2，目前只能在Kubernetes节点上才能访问，跳过之外是不能访问的。
[root@master ~]# curl 10.244.1.2 <!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>
service创建
事实上，上述的访问是不可取的，虽然可以访问，但容器的ip可能随时都会被修改或者其他情况导致该ip不可被访问。
此时就需要使用到
service固定访问端点。使用kubectl expose来创建。
使用说明如下:
Usage: kubectl expose (-f FILENAME | TYPE NAME) [--port=port] [--protocol=TCP|UDP|SCTP] [--target-port=number-or-name] [--name=name] [--external-ip=external-ip-of-service] [--type=type] [options]
注意： --target-port 表示容器上的端口，--name 表示service的名称，而 --port 表示service暴露的端口
--type=type 类型有： ClusterIP, NodePort, LoadBalancer, or ExternalName. Default is 'ClusterIP'.
下面开始创建：
[root@master ~]# kubectl expose deployment nginx-deploy --name=nginx --port=80 --target-port=80 --protocol=TCP service/nginx exposed
查看
[root@master ~]# kubectl get service NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.1.0.1 <none> 443/TCP 25h nginx ClusterIP 10.1.196.89 <none> 80/TCP 24s
这里的访问，直接访问刚刚创建的nginx service所对应的ip
[root@master ~]# curl 10.1.196.89 <!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>
这里需要用到coreDNS，来解析对应的service，这样外部即可访问。要配置coreDNS的域名解析才可。
测试其他pod通过series访问nginx
在master上查看kube-dns 信息
[root@master ~]# kubectl get service -n kube-system NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kube-dns ClusterIP 10.1.0.10 <none> 53/UDP,53/TCP,9153/TCP 25h
创建一个pod，并使用 -it 参数进入到容器中。
[root@master ~]# kubectl run -i -t busybox --image=busybox --restart=Never If you don't see a command prompt, try pressing enter. / #
查看 resolv.conf 文件中DNS
/ # cat /etc/resolv.conf nameserver 10.1.0.10 search default.svc.cluster.local svc.cluster.local cluster.local options ndots:5 / #
尝试解析nginx service
/ # nslookup nginx Server: 10.1.0.10 Address: 10.1.0.10:53 ** server can't find nginx.default.svc.cluster.local: NXDOMAIN *** Can't find nginx.svc.cluster.local: No answer *** Can't find nginx.cluster.local: No answer *** Can't find nginx.default.svc.cluster.local: No answer *** Can't find nginx.svc.cluster.local: No answer *** Can't find nginx.cluster.local: No answer / # nslookup nginx.default.svc.cluster.local Server: 10.1.0.10 Address: 10.1.0.10:53 *** Can't find nginx.default.svc.cluster.local: No answer
可以看到可以解析，尝试访问：
/ # wget -O - -q http://nginx <!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> / #
可以直接在busybox中访问 刚刚创建的nginx，没问题。
测试手动变更nginx对应的pod的ip
手动删除一下nginx的pod，这样，ip就会变更，然后在busybox中使用相同的service端点看能否访问。
[root@master ~]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
busybox 1/1 Running 0 2m12s 10.244.2.2 node02 <none> <none>
nginx-deploy-7689897d8d-hkl8n 1/1 Running 0 4m5s 10.244.1.2 node01 <none> <none>
[root@master ~]# kubectl delete pod nginx-deploy-7689897d8d-hkl8n pod "nginx-deploy-7689897d8d-hkl8n" deleted
[root@master ~]# kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES busybox 1/1 Running 0 5m28s 10.244.2.2 node02 <none> <none> nginx-deploy-7689897d8d-mdkhx 1/1 Running 0 24s 10.244.2.3 node02 <none> <none>
可以看到，nginx-deploy 的ip已经变更，下面测试访问依然可以。
pod和service之间的关系
查看 nginx 的service 对应的详细信息；
[root@master ~]# wget -O - -q http://nginx [root@master ~]# kubectl describe svc nginx Name: nginx Namespace: default Labels: run=nginx-deploy Annotations: <none> Selector: run=nginx-deploy Type: ClusterIP IP: 10.1.196.89 Port: <unset> 80/TCP TargetPort: 80/TCP Endpoints: 10.244.2.3:80 Session Affinity: None Events: <none>
查看pod标签
[root@master ~]# kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS busybox 1/1 Running 0 7m56s run=busybox nginx-deploy-7689897d8d-mdkhx 1/1 Running 0 2m52s pod-template-hash=7689897d8d,run=nginx-deploy
这里可以看出，因为nginx-deply的pod中，有nginx-deploy标签，而nginx的service的Selector选择的正式nginx-deploy标签，所以会被选中。
这就是pod和service之间的关系
service调度测试
创建一个两个副本的pod
[root@master ~]# kubectl run myapp --image=ikubernetes/myapp:v1 --replicas=2 kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead. deployment.apps/myapp created
[root@master ~]# kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES busybox 0/1 Running 0 9m16s 10.244.2.2 node02 <none> <none> myapp-84cd4b7f95-45zrk 1/1 Running 0 24s 10.244.2.4 node02 <none> <none> myapp-84cd4b7f95-ws6qw 1/1 Running 0 24s 10.244.1.3 node01 <none> <none> nginx-deploy-7689897d8d-mdkhx 1/1 Running 0 4m12s 10.244.2.3 node02 <none> <none>
在busybox中直接访问myapp
/ # wget -O - -q http://10.244.1.4 Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a> / # wget -O - -q http://10.244.1.4/hostname.html myapp-84cd4b7f95-ws6qw / # wget -O - -q http://10.244.2.3 Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a> / # wget -O - -q http://10.244.2.3/hostname.html myapp-84cd4b7f95-45zrk
