为什么要有ingress，或者他解决了什么问题

Kubernetes提供了三种类型的Services:
ClusterIP: 为Service分配虚拟地址，但是该地址只能在Kubernetes集群内部中访问,这也是Services的默认类型
NodePort: 在ClusterIP基础上将服务绑定到集群节点的指定端口上，可以通过:NodePort访问Service。
LoadBalancer:在NodePort的基础上使用外部的负载均衡服务，通过该负载均衡服务来访问集群内部的Services,实际上经过了两层转发。

Ingress就是一系列的转发规则集合，通过它可以将集群内部的Service暴露给公网。它也是可操作的REST对象，可以通过API方便的创建一个Ingress对象：

Prepare Ingress Controller

Backend deployment and service

Prepare deployment.yaml file

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: default-http-backend
  labels:
    k8s-app: default-http-backend
  namespace: default
spec:
  replicas: 1
  template:
    metadata:
      labels:
        k8s-app: default-http-backend
    spec:
      terminationGracePeriodSeconds: 60
      containers:
      - name: default-http-backend
        # Any image is permissable as long as:
        # 1. It serves a 404 page at /
        # 2. It serves 200 on a /healthz endpoint
        image: gcr.io/google_containers/defaultbackend:1.0
        livenessProbe:
          httpGet:
            path: /healthz
            port: 8080
            scheme: HTTP
          initialDelaySeconds: 30
          timeoutSeconds: 5
        ports:
        - containerPort: 8080
        resources:
          limits:
            cpu: 10m
            memory: 20Mi
          requests:
            cpu: 10m
            memory: 20Mi

Prepare service yaml file

apiVersion: v1
kind: Service
metadata:
  name: default-http-backend
  namespace: default
  labels:
    k8s-app: default-http-backend
spec:
  ports:
  - port: 80
    targetPort: 8080
  selector:
    k8s-app: default-http-backend

Create the default backend deployment and service by executing these commands:

$ kubectl create -f nginx-default-backend-deployment.yaml
$ kubectl create -f nginx-default-backend-service.yaml

Creating the Ingress Controller Nginx Deployment and Service

1.Create deployment yaml file

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx-ingress-controller
  labels:
    k8s-app: nginx-ingress-controller
  namespace: default
spec:
  replicas: 1
  template:
    metadata:
      labels:
        k8s-app: nginx-ingress-controller
    spec:
      # hostNetwork makes it possible to use ipv6 and to preserve the source
      # IP correctly regardless of docker configuration.
      # However, it is not a hard dependency of the nginx-ingress-controller
      # itself, and it may cause issues if port 10254 already is taken on
      # the host.
      # Since hostPort is currently broken on CNI
      # (https://github.com/kubernetes/kubernetes/issues/31307), we have to
      # use hostNetwork where CNI is used, like with kubeadm.
      # hostNetwork: true
      terminationGracePeriodSeconds: 60
      containers:
      - image: gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.10
        name: nginx-ingress-controller
        readinessProbe:
          httpGet:
            path: /healthz
            port: 10254
            scheme: HTTP
        livenessProbe:
          httpGet:
            path: /healthz
            port: 10254
            scheme: HTTP
          initialDelaySeconds: 10
          timeoutSeconds: 1
        ports:
        - containerPort: 80
          hostPort: 80
        - containerPort: 443
          hostPort: 443
        env:
          - name: POD_NAME
            valueFrom:
              fieldRef:
                fieldPath: metadata.name
          - name: POD_NAMESPACE
            valueFrom:
              fieldRef:
                fieldPath: metadata.namespace
        args:
        - /nginx-ingress-controller
        - --default-backend-service=$(POD_NAMESPACE)/default-http-backend
        - --update-status=false

Create service yaml file

apiVersion: v1
kind: Service
metadata:
  name: nginx-ingress-controller
  namespace: default
  labels:
    k8s-app: nginx-ingress-controller
spec:
  type: LoadBalancer
  ports:
  - port: 80
    nodePort: 30021
    name: http
  - port: 443
    nodePort: 30022
    name: https
  selector:
    k8s-app: nginx-ingress-controller

Create the nginx ingress controller deployment and service by executing these commands:

$ kubectl create -f nginx-ingress-controller-deployment.yaml
$ kubectl create -f nginx-ingress-controller-service.yaml

Deploy demo service

Creating the docker-hello-world Service Definition

apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: docker-hello-world
  labels:
    app: docker-hello-world
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: docker-hello-world
    spec:
      containers:
      - name: docker-hello-world
        image: scottsbaldwin/docker-hello-world:latest
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: docker-hello-world-svc
spec:
  selector:
    app: docker-hello-world
  ports:
    - port: 8088
      targetPort: 80
  type: ClusterIP

Create this new deployment and service:

kubectl create -f hello-world-ingress.yaml

Create the file ingress.yaml and populate it with this code:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: hello-world-ing
  annotations:
    kubernetes.io/ingress.class: "nginx"
spec:
  rules:
  - host: hello.docker.svc
    http:
      paths:
      - backend:
          serviceName: docker-hello-world-svc
          servicePort: 8088

Create the ingress resource:

kubectl create -f ingress.yaml

Test the service ingress:

[test@demotest demo1]$ kubectl get ingress
NAME                  HOSTS              ADDRESS   PORTS     AGE
hello-world-ing       hello.docker.svc             80        6h
example-service-ing   hello.k8s.svc                80        1h
 
[test@demotest demo2]$ curl -H "Host:hello.docker.svc"  http://129.146.156.124/
<h1>Hello webhook world from: docker-hello-world-5866dbffbc-f4frr</h1>

Q&A

Q: Did not see reference from the demo service’ section, how do they find out the ingress controller you created and also what if there are multiple ingress controllers?
A: User can specify “–ingress-class” to define ingress class names to route through this controller when creating ingress controller. Please see https://github.com/kubernetes/ingress-nginx/blob/master/docs/user-guide/cli-arguments.md:

–ingress-class: Name of the ingress class this controller satisfies. The class of an Ingress object is set using the annotation “kubernetes.io/ingress.class”. All ingress classes are satisfied if this parameter is left empty.

And in this example, we didn’t specify this parameter for ingress controller, so all the igress classes can be routed through this controller.

args:
   - /nginx-ingress-controller
   - --default-backend-service=$(POD_NAMESPACE)/default-http-backend
   - --update-status=false

For multiple ingress controllers, you can refer to https://github.com/nginxinc/kubernetes-ingress/tree/master/examples/multiple-ingress-controllers

To designate that a particular Ingress resource must be handled only by the NGINX or NGINX Plus controller, add the following annotation along with the value to the Ingress resource:
kubernetes.io/ingress.class: “nginx”
In this case other Ingress controllers will ignore that Ingress.
To summarize, the NGINX or NGINX Plus controller will handle an Ingress resource, if one of the following is true:
The annotation is not present in the resource
The annotation is present and its value is either the nginx or the empty string
Any other value of the annotation, for example, gce, makes the NGINX or NGINX Plus controller ignore the Ingress resource.

And the key point per my understanding is that
1). define “–ingress-class” in ingress controller resource.
2). define “kubernetes.io/ingress.class:” annotation in ingress resource.

附录： Nginx 介绍

Nginx是一款自由的、开源的、高性能的HTTP服务器和反向代理服务器；同时也是一个IMAP、POP3、SMTP代理服务器；Nginx可以作为一个HTTP服务器进行网站的发布处理，另外Nginx可以作为反向代理进行负载均衡的实现。

正向代理：
正向代理最大的特点是客户端非常明确要访问的服务器地址。
正向代理的用途：
（1）访问原来无法访问的资源，如Google
（2）可以做缓存，加速访问资源
（3）对客户端访问授权，上网进行认证
（4）代理可以记录用户访问记录（上网行为管理），对外隐藏用户信息
反向代理：
反向代理，“它代理的是服务端”，主要用于服务器集群分布式部署的情况下，反向代理隐藏了服务器的信息。
反向代理的作用：
（1）保证内网的安全，通常将反向代理作为公网访问地址，Web服务器是内网
（2）负载均衡，通过反向代理服务器来优化网站的负载。

Nginx 配置文件

nginx.conf文件结构


  ...                      #全局块
  events{}                 #events块
    http{                  #http块
      ...                  #http全局块
      server{              #server块
        ...                #server全局块
        location [/]{      #location块
          ...
        }
      }
    }

全局块:nginx服务器的配置信息
events块:主要影响nginx服务器与用户的网络连接,
http块:代理缓存和日志定义绝大多数功能和第三方模块的配置可以放这
server块:每个server相当于一台虚拟主机,它内部可以有多台主机联合提供服务,一起对外提供在逻辑上关系密切的一组服务
location:基于nginx服务器接收到的请求字符串,对除虚拟主机名之外的字符串进行匹配,对特定的请求进行处理
在这里插入图片描述

举例：

状态监控模块：
在这里插入图片描述

Kubernetes 系列一 Setting Up an Ingress Controller on a Cluster

为什么要有ingress，或者他解决了什么问题

Prepare Ingress Controller

Backend deployment and service

Creating the Ingress Controller Nginx Deployment and Service

Deploy demo service

Q&A

附录： Nginx 介绍

Nginx 配置文件

举例：

猜你喜欢

Kubernetes 系列一 Setting Up an Ingress Controller on a Cluster

为什么要有ingress， 或者他解决了什么问题

Prepare Ingress Controller

Backend deployment and service

Creating the Ingress Controller Nginx Deployment and Service

Deploy demo service

Q&A

附录： Nginx 介绍

Nginx 配置文件

举例：

猜你喜欢

为什么要有ingress，或者他解决了什么问题