nginx.conf

worker_processes 1;
error_log /dev/stdout info;

events {
  worker_connections 1024;
}

http {
  access_log /dev/stdout;

  server {
    listen 80;

    # Use self-signed certificate in development mode. If it's production we do not
    # require it because Cloudflare gives us free SSL/TLS encryption.
    listen 443 ssl;
    listen [::]:443 ssl;
    server_name localhost;
    ssl_certificate /etc/ssl/certs/selfsigned.crt;
    ssl_certificate_key /etc/ssl/private/selfsigned.key;
    ssl_protocols TLSv1.2 TLSv1.1 TLSv1;

    location /api/ {
      proxy_pass http://backend:6000/;
    }

    location /socket.io/ {
      # Configuration needed for socket.io to work.
      #
      #     https://www.nginx.com/blog/nginx-nodejs-websockets-socketio/
      #
      proxy_http_version 1.1;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

      proxy_set_header Upgrade $http_upgrade;
      proxy_set_header Connection "upgrade";

      proxy_pass http://frontend:3000;
    }

    location / {
      proxy_pass http://frontend:3000;
    }
  }
}