docker-nginx.conf

user nginx;
worker_processes auto;
pid /run/nginx.pid;

events {
    worker_connections 1024;
}

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    sendfile on;
    server_tokens off;

    access_log off;
    error_log /dev/stderr;

    server {
        listen      8000;
        server_name _;

        # HTML client
        location / {
            root  /app/client;
            index index.html;
        }

        location = /status {
            add_header Content-Type text/plain;
            return 200 'ok';
        }

        # socket.io forwarding
        location /socket.io/ {
            proxy_pass http://localhost:3000;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
        }
    }
}