234 lines
6.5 KiB
Markdown
234 lines
6.5 KiB
Markdown
# 安装traefik ingress
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## Ingress简介
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如果你还不了解，ingress是什么，可以先看下我翻译的Kubernetes官网上ingress的介绍[Kubernetes Ingress解析](http://rootsongjc.github.io/blogs/kubernetes-ingress-resource/)。
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**理解Ingress**
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简单的说，ingress就是从kubernetes集群外访问集群的入口，将用户的URL请求转发到不同的service上。Ingress相当于nginx、apache等负载均衡方向代理服务器，其中还包括规则定义，即URL的路由信息，路由信息得的刷新由[Ingress controller](https://kubernetes.io/docs/concepts/services-networking/ingress/#ingress-controllers)来提供。
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**理解Ingress Controller**
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Ingress Controller 实质上可以理解为是个监视器，Ingress Controller 通过不断地跟 kubernetes API 打交道，实时的感知后端 service、pod 等变化，比如新增和减少 pod，service 增加与减少等；当得到这些变化信息后，Ingress Controller 再结合下文的 Ingress 生成配置，然后更新反向代理负载均衡器，并刷新其配置，达到服务发现的作用。
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## 部署Traefik
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**介绍traefik**
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[Traefik](https://traefik.io/)是一款开源的反向代理与负载均衡工具。它最大的优点是能够与常见的微服务系统直接整合，可以实现自动化动态配置。目前支持Docker, Swarm, Mesos/Marathon, Mesos, Kubernetes, Consul, Etcd, Zookeeper, BoltDB, Rest API等等后端模型。
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以下配置文件可以在[kubernetes-handbook](https://github.com/rootsongjc/kubernetes-handbook)GitHub仓库中的[manifests/traefik-ingress/](../manifests/traefik-ingress/)目录下找到。
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**创建ingress-rbac.yaml**
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将用于service account验证。
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```Yaml
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apiVersion: v1
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kind: ServiceAccount
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metadata:
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name: ingress
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namespace: kube-system
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---
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kind: ClusterRoleBinding
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apiVersion: rbac.authorization.k8s.io/v1beta1
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metadata:
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name: ingress
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subjects:
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- kind: ServiceAccount
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name: ingress
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namespace: kube-system
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roleRef:
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kind: ClusterRole
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name: cluster-admin
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apiGroup: rbac.authorization.k8s.io
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```
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**创建名为`traefik-ingress`的ingress**，文件名traefik.yaml
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```yaml
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apiVersion: extensions/v1beta1
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kind: Ingress
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metadata:
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name: traefik-ingress
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spec:
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rules:
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- host: traefik.nginx.io
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http:
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paths:
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- path: /
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backend:
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serviceName: my-nginx
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servicePort: 80
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- host: traefik.frontend.io
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http:
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paths:
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- path: /
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backend:
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serviceName: frontend
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servicePort: 80
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```
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这其中的`backend`中要配置default namespace中启动的service名字。`path`就是URL地址后的路径，如traefik.frontend.io/path，service将会接受path这个路径，host最好使用service-name.filed1.filed2.domain-name这种类似主机名称的命名方式，方便区分服务。
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根据你自己环境中部署的service的名字和端口自行修改，有新service增加时，修改该文件后可以使用`kubectl replace -f traefik.yaml`来更新。
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我们现在集群中已经有两个service了，一个是nginx，另一个是官方的`guestbook`例子。
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**创建Depeloyment**
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```Yaml
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apiVersion: extensions/v1beta1
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kind: Deployment
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metadata:
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name: traefik-ingress-lb
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namespace: kube-system
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labels:
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k8s-app: traefik-ingress-lb
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spec:
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template:
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metadata:
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labels:
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k8s-app: traefik-ingress-lb
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name: traefik-ingress-lb
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spec:
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terminationGracePeriodSeconds: 60
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hostNetwork: true
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restartPolicy: Always
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serviceAccountName: ingress
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containers:
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- image: traefik
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name: traefik-ingress-lb
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resources:
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limits:
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cpu: 200m
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memory: 30Mi
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requests:
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cpu: 100m
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memory: 20Mi
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ports:
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- name: http
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containerPort: 80
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hostPort: 80
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- name: admin
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containerPort: 8580
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hostPort: 8580
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args:
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- --web
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- --web.address=:8580
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- --kubernetes
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```
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注意我们这里用的是Deploy类型，没有限定该pod运行在哪个主机上。Traefik的端口是8580。
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**Traefik UI**
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```yaml
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apiVersion: v1
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kind: Service
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metadata:
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name: traefik-web-ui
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namespace: kube-system
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spec:
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selector:
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k8s-app: traefik-ingress-lb
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ports:
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- name: web
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port: 80
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targetPort: 8580
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---
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apiVersion: extensions/v1beta1
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kind: Ingress
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metadata:
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name: traefik-web-ui
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namespace: kube-system
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spec:
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rules:
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- host: traefik-ui.local
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http:
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paths:
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- path: /
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backend:
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serviceName: traefik-web-ui
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servicePort: web
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```
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配置完成后就可以启动treafik ingress了。
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```
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kubectl create -f .
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```
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我查看到traefik的pod在`172.20.0.115`这台节点上启动了。
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访问该地址`http://172.20.0.115:8580/`将可以看到dashboard。
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左侧黄色部分部分列出的是所有的rule，右侧绿色部分是所有的backend。
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## 测试
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在集群的任意一个节点上执行。假如现在我要访问nginx的"/"路径。
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```bash
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$ curl -H Host:traefik.nginx.io http://172.20.0.115/
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<!DOCTYPE html>
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<html>
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<head>
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<title>Welcome to nginx!</title>
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<style>
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body {
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width: 35em;
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margin: 0 auto;
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font-family: Tahoma, Verdana, Arial, sans-serif;
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}
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</style>
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</head>
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<body>
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<h1>Welcome to nginx!</h1>
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<p>If you see this page, the nginx web server is successfully installed and
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working. Further configuration is required.</p>
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<p>For online documentation and support please refer to
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<a href="http://nginx.org/">nginx.org</a>.<br/>
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Commercial support is available at
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<a href="http://nginx.com/">nginx.com</a>.</p>
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<p><em>Thank you for using nginx.</em></p>
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</body>
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</html>
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```
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如果你需要在kubernetes集群以外访问就需要设置DNS，或者修改本机的hosts文件。
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在其中加入：
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```
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172.20.0.115 traefik.nginx.io
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172.20.0.115 traefik.frontend.io
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```
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所有访问这些地址的流量都会发送给172.20.0.115这台主机，就是我们启动traefik的主机。
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Traefik会解析http请求header里的Host参数将流量转发给Ingress配置里的相应service。
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修改hosts后就就可以在kubernetes集群外访问以上两个service，如下图：
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## 参考
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[Traefik-kubernetes 初试](http://www.colabug.com/thread-1703745-1-1.html)
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[Traefik简介](http://www.tuicool.com/articles/ZnuEfay)
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[Guestbook example](https://github.com/kubernetes/kubernetes/tree/master/examples/guestbook) |