在Serverless Kubernetes(ASK)集群中使用Nginx Ingress

导读

不同于阿里云ACK集群默认通过nginx-ingress-controller提供ingress能力，在ASK(Serverless Kubernetes)集群中默认基于SLB七层转发提供ingress能力（请参考文档https://help.aliyun.com/document_detail/86398.html）。这样的优势是Serverless集群开箱即用，用户无需部署任何controller即可创建自己的Ingress资源，更符合Serverless环境的用法。

然而基于SLB七层转发的ingress与nginx-ingress-controller相比，缺少了一些高级Ingress功能，无法满足某些客户场景的需求，比如支持域名path的正则匹配等。

所以ASK集群也提供了与ACK集群同样的nginx-ingress-controller，供用户使用nginx提供的ingress转发能力。用户可以根据自己的需求决定选择两者之一。下面我们一起来尝试在ASK集群中使用nginx-ingress。

部署nginx-ingress-controller

在ASK集群中部署yaml文件：
https://github.com/AliyunContainerService/serverless-k8s-examples/blob/master/ingress-nginx/nginx-ingress-controller.yaml

#kubectl apply -f https://raw.githubusercontent.com/AliyunContainerService/serverless-k8s-examples/master/ingress-nginx/nginx-ingress-controller.yaml
service/nginx-ingress-lb created
configmap/nginx-configuration created
configmap/tcp-services created
configmap/udp-services created
serviceaccount/nginx-ingress-controller created
clusterrole.rbac.authorization.k8s.io/nginx-ingress-controller created
clusterrolebinding.rbac.authorization.k8s.io/nginx-ingress-controller created
deployment.apps/nginx-ingress-controller created

# kubectl -n kube-system get pod
NAME                                       READY   STATUS    RESTARTS   AGE
nginx-ingress-controller-c9d8697f6-n4bzs   0/1     Running   0          52s
nginx-ingress-controller-c9d8697f6-p8p6j   0/1     Running   0          52s

# kubectl -n kube-system get svc
NAME               TYPE           CLUSTER-IP     EXTERNAL-IP    PORT(S)                      AGE
metrics-server     ClusterIP      172.19.4.171   <none>         443/TCP                      72d
nginx-ingress-lb   LoadBalancer   172.19.6.118   47.93.131.72   80:32676/TCP,443:30256/TCP   116s

可以看到一个公网slb已经被创建出来（后端是两个nginx-ingress-controller pod），这是集群中所有ingress的入口IP地址。

部署Ingress示例

我们同样提供了简单的Coffee和Tea Ingress示例：https://github.com/AliyunContainerService/serverless-k8s-examples/blob/master/ingress-nginx/ingress-cafe-demo.yaml

需要注意的是Ingress中需要指定如下Annotation，才能保证ingress被nginx-ingress-controller正确处理。
kubernetes.io/ingress.class：nginx

# kubectl apply -f https://raw.githubusercontent.com/AliyunContainerService/serverless-k8s-examples/master/ingress-nginx/ingress-cafe-demo.yamldeployment.extensions/coffee created
service/coffee-svc created
deployment.extensions/tea created
service/tea-svc created
ingress.extensions/cafe-ingress created

# kubectl get pod
NAME                             READY   STATUS             RESTARTS   AGE
coffee-56668d6f78-g7g6p          1/1     Running            0          88s
coffee-56668d6f78-x9ktc          1/1     Running            0          88s
tea-85f8bf86fd-477d2             1/1     Running            0          88s
tea-85f8bf86fd-jlq6b             1/1     Running            0          88s
tea-85f8bf86fd-p4ng4             1/1     Running            0          88s

# kubectl get svc
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
coffee-svc   ClusterIP   None            <none>        80/TCP     102s
kubernetes   ClusterIP   172.19.0.1      <none>        443/TCP    72d
tea-svc      ClusterIP   None            <none>        80/TCP     102s

# kubectl get ing
NAME           HOSTS              ADDRESS        PORTS   AGE
cafe-ingress   cafe.example.com   47.93.131.72   80      2m1s

pod和ingress都已创建成功，下面我们尝试访问Ingress：

# curl -H "Host:cafe.example.com" 47.93.131.72/tea
Server address: 192.168.55.159:80
Server name: default-tea-85f8bf86fd-p4ng4
Date: 14/Nov/2019:09:01:46 +0000
URI: /tea
Request ID: 2c3a87eb89130d62664b640fcbabc74b

# curl -H "Host:cafe.example.com" 47.93.131.72/coffee
Server address: 192.168.55.156:80
Server name: default-coffee-56668d6f78-x9ktc
Date: 14/Nov/2019:09:01:49 +0000
URI: /coffee
Request ID: a4f1d84bb5288a260ecfc5d21ecccff6

Ingress链路访问成功，可以看到上述域名转发由nginx ingress controller完成。

更多ASK集群示例请参考：https://github.com/AliyunContainerService/serverless-k8s-examples

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