Ingress-Nginx 控制器入门

Kubernetes 提供了两种负载均衡的机制用于发布公共服务，一种是工作在传输层的Service资源，一种是Ingress资源。前者只能实现”TCP负载均衡”，而无法实现 HTTPS 协议，而Ingress 的出现为我们提供了应用层HTTP(S)的访问能力。

部署 Ingress Controller

Ingress 是 Kubernetes API 的标准类型资源，它是一组 基于DNS 名称或者 URL 路径把用户请求转发到指定的Service资源的规则，用于将集群外部的请求流量转发至集群内部完成服务发布。然而， Ingress 本身并不能进行流量转发，它仅仅是一组路由规则，如果想要真正的使这对规则生效，则需要先部署 Ingress 的控制器，Ingress 控制器能够监听某一个套接字，然后根据Ingress上的路由规则对用户的请求进行转发。

~]# kubectl apply -f https://raw.githubusercontent.com/imirsh/kubernetes/master/mainfests/ingress-nginx/v0.33.0/deploy.yaml

验证安装

确认 ingress controller pods 是否启动

~]# kubectl get pods -n ingress-nginx -l app.kubernetes.io/name=ingress-nginx --watch
NAME                                        READY   STATUS      RESTARTS   AGE
ingress-nginx-admission-create-hh2ht        0/1     Completed   0          20m
ingress-nginx-admission-patch-9npbv         0/1     Completed   0          20m
ingress-nginx-controller-566d9467c5-8lssn   1/1     Running     0          20m

~]# kubectl  get svc -n ingress-nginx
NAME                                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                      AGE
ingress-nginx-controller             NodePort    10.103.127.175   <none>        80:30080/TCP,443:30443/TCP   21m
ingress-nginx-controller-admission   ClusterIP   10.98.11.81      <none>        443/TCP                      21m

测试http 7层负载

部署了完 ingress-nginx后，部署了一个 deployment，并它创建了一个名为 myapp-svc-v1 的 service：

~]# vim myapp-deploy.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: deploy-http-v1
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
      app: myapp-v1
      version: v1
  template:
    metadata:
      namespace: default
      labels:
        app: myapp-v1
        version: v1
    spec:
      containers:
      - name: myapp-v1
        image: ikubernetes/myapp:v1
        imagePullPolicy: IfNotPresent
        ports:
        - name: http
          containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: myapp-svc-v1
  namespace: default
  labels:
    app: myapp-v1
    version: v1
spec:
  type: ClusterIP
  selector:
    app: myapp-v1
    version: v1
  ports:
  - name: http
    port: 80
    protocol: TCP
    targetPort: 80

然后创建对应的一个ingress对象来暴露集群里这个 deployment 的 http 服务：

~]# vim ingress-myapp.yaml
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-myapp-v1
  annotations:
    kubernetes.io/ingress.class: "nginx"
spec:
  rules:
  - host: myapp-v1.linux.io
    http:
      paths:
      - path: /
        backend:
          serviceName: myapp-svc-v1
          servicePort: 80

hosts 文件解析后，即可通过域名访问了

~]# curl http://myapp-v1.linux.io:30080/
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>