Dynamic reverse proxy using nginx in Kubernetes

1. create a configmap.yaml  

apiVersion: v1
kind: ConfigMap
metadata:
  name: confnginx
data:
  nginx.conf: |
    user  nginx;
    worker_processes  1;
    error_log  /var/log/nginx/error.log warn;
    pid        /var/run/nginx.pid;
    events {
        worker_connections  1024;
    }
    http {
      include       /etc/nginx/mime.types;
      default_type  application/octet-stream;
      log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                          '$status $body_bytes_sent "$http_referer" '
                          '"$http_user_agent" "$http_x_forwarded_for"';
      access_log  /var/log/nginx/access.log  main;
      sendfile        on;
      keepalive_timeout  65;
      server {
        listen 80;

        server_name ~^(?<subdomain>.*?)\.;
        resolver kube-dns.kube-system.svc.cluster.local valid=5s;

        location /healthz {
          return 200;
        }

        location / {
          proxy_set_header Upgrade $http_upgrade;
          proxy_set_header Connection "Upgrade";
          proxy_pass http://$subdomain.msce0.svc.cluster.local;
          proxy_set_header Host $host;
          proxy_http_version 1.1;
        }
      }
    }

 run

kubectl apply -f configmap.yaml

2. create a service.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:alpine
          ports:
          - containerPort: 80
          volumeMounts:
            - name: nginx-config
              mountPath: /etc/nginx/nginx.conf
              subPath: nginx.conf
      volumes:
        - name: nginx-config
          configMap:
            name: confnginx

run

kubectl apply -f service.yaml