nginx.conf

upstream index {
  server 127.0.0.1:4200;
}
upstream app1 {
  server 127.0.0.1:4201;
}
upstream app2 {
  server 127.0.0.1:4202;
}


map $http_upgrade $connection_upgrade {
  default upgrade;
  '' close;
}

map $request_uri $app {
  default "index";
  "~^/(?P<p>[^/]*).*" $p; 
}


server {
  listen 80;
  server_name sub.domain.com;

  location / {
    rewrite ^/[^/]*/?(.*) /$1 break;
    include proxy_params;
    proxy_redirect off;
    proxy_pass http://$app;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection $connection_upgrade;
  }
}