Kubernetes Ingress

Ingress是什么？

An API object that manages external access to the services in a cluster, typically HTTP.

Ref: https://kubernetes.io/docs/concepts/services-networking/ingress/

HTTP方式暴露K8S服务到集群外面。

和NodePort方式和LoadBalancer方式的不同？

An Ingress does not expose arbitrary ports or protocols. Exposing services other than HTTP and HTTPS to the internet typically uses a service of type Service.Type=NodePort or Service.Type=LoadBalancer.

除了提供HTTP,HTTPS的服务之外， 还有很多以TCP方式提供服务的如Redis等数据库是不能用Ingress方式暴露服务的，也就是说Ingress只适合Web应用或提供HTTP Restful API的应用。

部署Ingress Controller

Nginx

这个找Docker镜像真的是很烦，有一个库：https://quay.io/repository/被墙了，所以镜像包一直下载不下来，
可以去Docker hub上找一个镜像：

很奇怪，我这里下载了之后，docker竟然自动给镜像打了另一个tag.

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1siriuszg/nginx-ingress-controller                                 latest              d9cfa0cf4118        4 weeks ago         483MB

2quay.io/kubernetes-ingress-controller/nginx-ingress-controller    0.26.1              29024c9c6e70        6 weeks ago         483MB

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pod日志里面，额，什么都没有：

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1Events:

2  Type     Reason          Age                From                 Message

3  ----     ------          ----               ----                 -------

4  Normal   Scheduled       <unknown>          default-scheduler    Successfully assigned ingress-nginx/nginx-ingress-controller-568867bf56-6h6fv to k8s-master

5  Warning  Failed          42m                kubelet, k8s-master  Failed to pull image "quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.26.1": rpc error: code = Unknown desc = read tcp 192.168.0.148:60704->99.86.193.171:443: read: connection reset by peer

6  Warning  Failed          31m (x3 over 52m)  kubelet, k8s-master  Failed to pull image "quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.26.1": rpc error: code = Unknown desc = net/http: TLS handshake timeout

7  Normal   Pulling         31m (x5 over 65m)  kubelet, k8s-master  Pulling image "quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.26.1"

8  Warning  Failed          30m (x5 over 52m)  kubelet, k8s-master  Error: ErrImagePull

9  Warning  Failed          30m                kubelet, k8s-master  Failed to pull image "quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.26.1": rpc error: code = Unknown desc = unexpected EOF

10  Normal   SandboxChanged  30m                kubelet, k8s-master  Pod sandbox changed, it will be killed and re-created.

11  Normal   BackOff         30m (x7 over 52m)  kubelet, k8s-master  Back-off pulling image "quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.26.1"

12  Warning  Failed          30m (x7 over 52m)  kubelet, k8s-master  Error: ImagePullBackOff

13  Normal   Pulled          29s                kubelet, k8s-master  Successfully pulled image "quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.26.1"

14  Normal   Created         29s                kubelet, k8s-master  Created container nginx-ingress-controller

15  Normal   Started         28s                kubelet, k8s-master  Started container nginx-ingress-controller

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总之，镜像搞定了，服务也自动起来了。

Ref

https://github.com/kubernetes/ingress-nginx/blob/master/docs/deploy/index.md\#verify-installation

创建Ingress对象

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1apiVersion: networking.k8s.io/v1beta1

2kind: Ingress

3metadata:

4  name: test-ingress

5  annotations:

6    nginx.ingress.kubernetes.io/rewrite-target: /

7spec:

8  rules:

9  - http:

10      paths:

11      - path: /testpath    

12        backend:

13          -- 后端的服务名和端口

14          serviceName: test  

15          servicePort: 80

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1$ kubectl get ingress test-ingress

2NAME           HOSTS   ADDRESS   PORTS   AGE

3test-ingress   *                 80      3m35s

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bare-metal

这里发现我这里Ingress没有被分配ADDRESS,少一个步骤是：

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1kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/provider/baremetal/service-nodeport.yaml

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因为我是自己虚拟机搭建，所以属于Bare-metal,而不属于Cloud-Provider.
这个步骤执行完，

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1[root@k8s-master tomcat]# kubectl get svc -n ingress-nginx

2NAME            TYPE       CLUSTER-IP      EXTERNAL-IP   PORT(S)                      AGE

3ingress-nginx   NodePort   10.97.136.122   <none>        80:31164/TCP,443:32406/TCP   28s

4[root@k8s-master tomcat]#  kubectl get ingress test-ingress

5NAME           HOSTS   ADDRESS         PORTS   AGE

6test-ingress   *       10.97.136.122   80      25m

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之后我可以在物理机上通过http://192.168.0.148:31164/tomcat来访问tomcat服务，但是页面的CSS都找不到，通过端口直接暴露的却可以找到。

???

Reference List

1. https://kubernetes.io/docs/concepts/services-networking/ingress/