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7 Ingress

7 Ingress

Ingressopen in new window 公开从集群外部到集群内服务open in new window的 HTTP 和 HTTPS 路由。 流量路由由 Ingress 资源上定义的规则控制。Ingress 可为 Service 提供外部可访问的 URL、负载均衡流量、 SSL/TLS，以及基于名称的虚拟托管。你必须拥有一个 Ingress 控制器open in new window 才能满足 Ingress 的要求。 仅创建 Ingress 资源本身没有任何效果。 Ingress 控制器open in new window 通常负责通过负载均衡器来实现 Ingress，例如 minikube 默认使用的是 nginx-ingressopen in new window，目前 minikube 也支持 Kong-Ingressopen in new window。

Ingress 可以“简单理解”为服务的网关 Gateway，它是所有流量的入口，经过配置的路由规则，将流量重定向到后端的服务。

在 minikube 中，可以通过下面命令开启 Ingress-Controller 的功能。默认使用的是 nginx-ingressopen in new window。

minikube addons enable ingress

接着删除之前创建的所有 pod, deployment, service 资源。

kubectl delete deployment,service --all

接着根据之前的教程，创建 hellok8s:v3 和 nginx 的deployment与 service 资源。Service 的 type 为 ClusterIP 即可。

hellok8s:v3 的端口映射为 3000:3000，nginx 的端口映射为 4000:80，这里后续写 Ingress Route 规则时会用到。

apiVersion: v1
kind: Service
metadata:
  name: service-hellok8s-clusterip
spec:
  type: ClusterIP
  selector:
    app: hellok8s
  ports:
  - port: 3000
    targetPort: 3000

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hellok8s-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: hellok8s
  template:
    metadata:
      labels:
        app: hellok8s
    spec:
      containers:
        - image: guangzhengli/hellok8s:v3
          name: hellok8s-container

apiVersion: v1
kind: Service
metadata:
  name: service-nginx-clusterip
spec:
  type: ClusterIP
  selector:
    app: nginx
  ports:
  - port: 4000
    targetPort: 80

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx
        name: nginx-container

kubectl apply -f hellok8s.yaml                 
# service/service-hellok8s-clusterip created
# deployment.apps/hellok8s-deployment created

kubectl apply -f nginx.yaml   
# service/service-nginx-clusterip created
# deployment.apps/nginx-deployment created

kubectl get pods            
# NAME                                   READY   STATUS    RESTARTS   AGE
# hellok8s-deployment-5d5545b69c-4wvmf   1/1     Running   0          55s
# hellok8s-deployment-5d5545b69c-qcszp   1/1     Running   0          55s
# hellok8s-deployment-5d5545b69c-sn7mn   1/1     Running   0          55s
# nginx-deployment-d47fd7f66-d9r7x       1/1     Running   0          34s
# nginx-deployment-d47fd7f66-hp5nf       1/1     Running   0          34s

kubectl get service
# NAME                         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
# service-hellok8s-clusterip   ClusterIP   10.97.88.18      <none>        3000/TCP   77s
# service-nginx-clusterip      ClusterIP   10.103.161.247   <none>        4000/TCP   56s

这样在 k8s 集群中，就有 3 个 hellok8s:v3 的 pod，2 个 nginx 的 pod。并且hellok8s:v3 的端口映射为 3000:3000，nginx 的端口映射为 4000:80。在这个基础上，接下来编写 Ingress 资源的定义，nginx.ingress.kubernetes.io/ssl-redirect: "false" 的意思是这里关闭 https 连接，只使用 http 连接。

匹配前缀为 /hello 的路由规则，重定向到 hellok8s:v3 服务，匹配前缀为 / 的跟路径重定向到 nginx。

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: hello-ingress
  annotations:
    # We are defining this annotation to prevent nginx
    # from redirecting requests to `https` for now
    nginx.ingress.kubernetes.io/ssl-redirect: "false"
spec:
  rules:
    - http:
        paths:
          - path: /hello
            pathType: Prefix
            backend:
              service:
                name: service-hellok8s-clusterip
                port:
                  number: 3000
          - path: /
            pathType: Prefix
            backend:
              service:
                name: service-nginx-clusterip
                port:
                  number: 4000


kubectl apply -f ingress.yaml
# ingress.extensions/hello-ingress created

kubectl get ingress          
# NAME            CLASS   HOSTS   ADDRESS   PORTS   AGE
# hello-ingress   nginx   *                 80      16s

# replace 192.168.59.100 by your minikube ip
curl http://192.168.59.100/hello
# [v3] Hello, Kubernetes!, From host: hellok8s-deployment-5d5545b69c-sn7mn

curl http://192.168.59.100/
# (....Thank you for using nginx.....)

这里和service一样，如果本地使用 Docker Desktop（minikube start --driver=docker）的话，那你大概率无法通过minikube ip获取到的ip地址来请求，你可以先通过minikube service list来查看服务列表，然后通过minikube service ingress-nginx-controller -n ingress-nginx --url来公开服务，然后通过curl或者浏览器来访问。

minikube service list
# |---------------|------------------------------------|--------------|---------------------------|
# |   NAMESPACE   |                NAME                | TARGET PORT  |            URL            |
# |---------------|------------------------------------|--------------|---------------------------|
# | default       | kubernetes                         | No node port |
# | default       | service-hellok8s-clusterip         | No node port |
# | default       | service-nginx-clusterip            | No node port |
# | ingress-nginx | ingress-nginx-controller           | http/80      | http://192.168.49.2:32339 |
# |               |                                    | https/443    | http://192.168.49.2:32223 |
# | ingress-nginx | ingress-nginx-controller-admission | No node port |
# | kube-system   | kube-dns                           | No node port |
# |---------------|------------------------------------|--------------|---------------------------|
minikube service ingress-nginx-controller -n ingress-nginx --url
# http://127.0.0.1:61691      http
# http://127.0.0.1:61692      https
# ❗  Because you are using a Docker driver on windows, the terminal needs to be open to run it.
# 第一个是http，第二个是https，这里我们只需要http，所以我们只需要第一个地址
curl http://127.0.0.1:61691/hello
# [v3] Hello, Kubernetes!, From host: hellok8s-deployment-5d5545b69c-sn7mn
curl http://127.0.0.1:61691/
# (....Thank you for using nginx.....)

上面的教程中将所有流量都发送到 Ingress 中，如下图所示：

ingress
ingress
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