kubernetes(六)系列之Ingress

ingress

Ingress 公开从集群外部到集群内服务的 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-ingress，目前 minikube 也支持 Kong-Ingress。

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-ingress。

shell
minikube addons enable ingress

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

shell
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。

yaml
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

yaml
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

shell
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。

yaml
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

shell
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.....)

上面的教程中将所有流量都发送到 Ingress 中，如下图所示：

ingress

目录

ingress