为什么需要ingress？

Ingress 只需要一个公网ip就能为许多服务提供访问，当客户端向ingress发送HTTP请求时，Ingress 会根据请求的主机名和路径决定请求转发到的服务

部署测试demo

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

验证安装

kubectl get pods --all-namespaces -l app.kubernetes.io/name=ingress-nginx --watch
POD_NAMESPACE=ingress-nginx
POD_NAME=$(kubectl get pods -n $POD_NAMESPACE -l app.kubernetes.io/name=ingress-nginx -o jsonpath='{.items[0].metadata.name}')

kubectl exec -it $POD_NAME -n $POD_NAMESPACE -- /nginx-ingress-controller --version

参考link https://kubernetes.github.io/ingress-nginx/deploy/#bare-metal

apiVersion: v1
kind: Service
metadata:
  name: ingress-nginx
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  type: NodePort
  ports:
    - name: http
      port: 80
      targetPort: 80
      protocol: TCP
    - name: https
      port: 443
      targetPort: 443
      protocol: TCP
    - name: proxied-tcp-9000
      port: 9000
      targetPort: 9000
      protocol: TCP
  selector:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

测试http 7层负载

kubectl run test-hello --image=nginx:alpine --expose --port=80
##
# kubectl get deploy test-hello
NAME         DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
test-hello   1         1         1            1           56s
# kubectl get svc test-hello
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
test-hello   ClusterIP   10.68.124.115   <none>        80/TCP    1m

• 然后为这个应用创建 ingress

```
# test-hello.ing.yaml内容
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: test-hello
spec:
  rules:
  - host: hello.test.com
    http:
      paths:
      - path: /
        backend:
          serviceName: test-hello
          servicePort: 80

• 集群内部尝试访问: curl -H Host:hello.test.com 10.68.69.170(ingress-service的服务地址) 能够看到欢迎页面 Welcome to nginx!；

TCP /UDP

Ingress does not support TCP or UDP services. For this reason this Ingress controller uses the flags --tcp-services-configmap and --udp-services-configmap to point to an existing config map where the key is the external port to use and the value indicates the service to expose using the format: <namespace/service name>:<service port>:[PROXY]:[PROXY]

apiVersion: v1
kind: ConfigMap
metadata:
  name: tcp-services
  namespace: ingress-nginx
data:
  9000: "default/example-go:8080"

参考官网 https://kubernetes.github.io/ingress-nginx/user-guide/exposing-tcp-udp-services/