随着RC的退出，Deployment作为Pod的控制器之一使用地越来越广泛，这篇文章以nginx服务为例，介绍一下使用的方式。
事前准备
本文使用Kubernetes 1.17.2，可参看下文进行快速环境搭建：
[root@host131 ansible]# kubectl get node -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
192.168.163.131 Ready <none> 2m25s v1.17.2 192.168.163.131 <none> CentOS Linux 7 (Core) 3.10.0-957.el7.x86_64 docker://19.3.5
[root@host131 ansible]#
Deployment配置文件
使用如下yaml文件用于设定Deployment
[root@host131 nginx]# cat deployment.yml
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
spec:
replicas: 1
selector:
matchLabels:
app: nginx-app
template:
metadata:
labels:
app: nginx-app
spec:
containers:
- name: nginx-host
image: nginx:1.17.8-alpine
ports:
- containerPort: 80
...
[root@host131 nginx]#
- 注意事项：matchLabels的内容需要与template中metadata的labels内容匹配，不过不用担心，在创建时会进行检查，比如将matchLabels改为app: nginx-app1，创建时会提示如下错误信息
[root@host131 nginx]# kubectl create -f deployment.yml
The Deployment "nginx-deployment" is invalid: spec.template.metadata.labels: Invalid value: map[string]string{"app":"nginx-app1"}: `selector` does not match template `labels`
[root@host131 nginx]#
Service配置文件
使用如下Service配置文件
[root@host131 nginx]# cat service.yml
---
apiVersion: v1
kind: Service
metadata:
name: nginx-service
labels:
app: nginx-service-app
spec:
type: NodePort
ports:
- port: 80
nodePort: 30000
selector:
app: nginx-app
...
[root@host131 nginx]#
- 注意事项：selector关联的需要是Deployment中template定义的label。
生成Deployment
使用Deployment的配置文件生成Deployment
[root@host131 nginx]# kubectl create -f deployment.yml
deployment.apps/nginx-deployment created
[root@host131 nginx]#
结果确认
[root@host131 nginx]# kubectl get deployment -o wide |grep nginx
nginx-deployment 1/1 1 1 34s nginx-host nginx:1.17.8-alpine app=nginx-app
[root@host131 nginx]#
[root@host131 nginx]# kubectl get pods -o wide |grep nginx
nginx-deployment-7c5b8fc568-wkh9b 1/1 Running 0 51s 10.254.152.6 192.168.163.131 <none> <none>
[root@host131 nginx]#
[root@host131 nginx]#
[root@host131 nginx]# kubectl exec -it nginx-deployment-7c5b8fc568-wkh9b sh
/ # hostname
nginx-deployment-7c5b8fc568-wkh9b
/ #
生成Service
[root@host131 nginx]# kubectl create -f service.yml
service/nginx-service created
[root@host131 nginx]#
结果确认
[root@host131 nginx]# kubectl get service -o wide |grep nginx
nginx-service NodePort 10.254.77.182 <none> 80:30000/TCP 9s app=nginx-app
[root@host131 nginx]#
nginx使用：集群地址访问
在集群所在的集群中，可以使用集群地址+80端口进行访问
[root@host131 nginx]# curl http://10.254.77.182
<!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>
[root@host131 nginx]#
也可以利用NodePort端口结合宿主机IP进行访问
[root@host131 nginx]# curl http://192.168.163.131:30000
<!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>
[root@host131 nginx]#
当然这种方式也可以直接使用浏览器进行确认
总结
Deployment作为Pod的控制器，可以对Pod进行创建、滚动升级等常见操作，这篇文章以nginx服务为例进行说明，介绍了Deployment和Service在Kubernetes中最常见的使用方式之一。
