2.3 在Kubernetes上运行第一个应用

参考文章

作者：老谭涮菜
链接：https://www.jianshu.com/p/6549ef181e7b

Creating a Deployment

$ kubectl create deployment kubia --image=luksa/kubia:1.0
deployment.apps/kubia created

Listing deployments

$ kubectl get deployments
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
kubia   0/1     1            0           6s

Listing pods

Listing 3.11 Listing pods
$ kubectl get pods
NAME                     READY     STATUS    RESTARTS   AGE
kubia-9d785b578-p449x    0/1       Pending   0          1m

Listing 3.12 The events displayed by kubectl describe pod
$kubectl describe pod
Events:
Type    Reason     Age   From               Message
----    ------     ----  ----               -------
Normal  Scheduled  25s   default-scheduler  Successfully assigned
                                            default/kubia-9d785b578-p449x
                                            to worker2
Normal  Pulling    23s   kubelet, worker2   Pulling image "luksa/kubia:1.0"
Normal  Pulled     21s   kubelet, worker2   Successfully pulled image
Normal  Created    21s   kubelet, worker2   Created container kubia
Normal  Started    21s   kubelet, worker2   Started container kubia

Creating a Service

$ kubectl expose deployment kubia --type=LoadBalancer --port 8080
service/kubia exposed

Listing services

Listing 3.13 Listing Services
$ kubectl get svc
NAME         TYPE          CLUSTER-IP     EXTERNAL-IP   PORT(S)         AGE
kubernetes   ClusterIP     10.19.240.1    <none>        443/TCP         34m
kubia        LoadBalancer  10.19.243.17   <pending>     8080:30838/TCP  4s

Listing 3.14 Getting a single service
$ kubectl get svc kubia
NAME        TYPE          CLUSTER-IP    EXTERNAL-IP    PORT(S)         AGE
kubia       LoadBalancer  10.19.243.17  35.246.179.22  8080:30838/TCP  82s

可以运行 minikube ssh 登录到Minikube集群内部
curl http://10.19.243.17:8080

Accessing your application through the load balance

$ curl 35.246.179.22:8080
Hey there, this is kubia-9d785b578-p449x. Your IP is ::ffff:1.2.3.4.

使用外部 IP 地址（LoadBalancer Ingress）访问 Hello World 应用程序:

curl http://<external-ip>:<port>
其中 <external-ip> 是您的服务的外部 IP 地址（LoadBalancer Ingress）， <port> 是您的服务描述中的 port 的值。

如果您正在使用 minikube，输入 minikube service kubia 获取可以访问服务的IP和端口 并在浏览器中自动打开 Hello World 应用程序。

水平伸缩应用

$ kubectl scale deployment kubia --replicas=3
deployment.apps/kubia scaled

Seeing the results of the scale-out

$ kubectl get deploy
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
kubia   3/3     3            3           18m

$ kubectl get pods
NAME                    READY   STATUS    RESTARTS   AGE
kubia-9d785b578-58vhc   1/1     Running   0          17s
kubia-9d785b578-jmnj8   1/1     Running   0          17s
kubia-9d785b578-p449x   1/1     Running   0          18m

Displaying the pods’ host node when listing pods

$ kubectl get pods -o wide
NAME                   ...  IP          NODE
kubia-9d785b578-58vhc  ...  10.244.1.5  worker1
kubia-9d785b578-jmnj8  ...  10.244.2.4  worker2
kubia-9d785b578-p449x  ...  10.244.2.3  worker2

Understanding the API objects representing your application

Listing 3.16 Requests sent to the service are spread across all the pods
$ curl 35.246.179.22:8080
Hey there, this is kubia-9d785b578-58vhc. Your IP is ::ffff:1.2.3.4.
$ curl 35.246.179.22:8080
Hey there, this is kubia-9d785b578-p449x. Your IP is ::ffff:1.2.3.4.
$ curl 35.246.179.22:8080
Hey there, this is kubia-9d785b578-jmnj8. Your IP is ::ffff:1.2.3.4.
$ curl 35.246.179.22:8080
Hey there, this is kubia-9d785b578-p449x. Your IP is ::ffff:1.2.3.4.

删除 Service：

kubectl delete services kubia 

清理

现在可以清理你在集群中创建的资源：

kubectl delete service kubia
kubectl delete deployment kubia

可选地，停止 Minikube 虚拟机（VM）：

minikube stop

可选地，删除 Minikube 虚拟机（VM）：

minikube delete