Unable to locate root directory of a web app in NGINX? - nginx

Question

I'm struggling with a NGINX based web app , i need to find its root directory that's being served. Its a subdomain and a simple nano /etc/nginx/sites-available/app.refridge.com it has the following contents.
##
# You should look at the following URL's in order to grasp a solid understanding
# of Nginx configuration files in order to fully unleash the power of Nginx.
# http://wiki.nginx.org/Pitfalls
# http://wiki.nginx.org/QuickStart
# http://wiki.nginx.org/Configuration
#
# Generally, you will want to move this file somewhere, and start with a clean
# file but keep this around for reference. Or just disable in sites-enabled.
#
# Please see /usr/share/doc/nginx-doc/examples/ for more detailed examples.
##
# Default server configuration
#
server {
listen *:80;
server_name app.refridge.com;
location / {
rewrite ^ https://$server_name$request_uri? permanent;
}
}
server {
listen *:443 ssl;
server_name app.refridge.com;
access_log /var/log/nginx/app.refridge.com-access.log;
error_log /var/log/nginx/app.refridge.com-error.log;
# SSL configuration
ssl_certificate /etc/nginx/ssl/STAR_refridge_com-bundle.crt;
ssl_certificate_key /etc/nginx/ssl/star_refridge_com.key;
# listen 443 ssl default_server;
There's no root defined even for port 80 and 443 but still the website loads. I mean is there anything i'm missing i need to find the files and do a backup thats why.
Any help would be appreciated.
P.S it's a DigitalOcean droplet.
**UPDATE: ** I think there a reverse proxy setup
location / {
proxy_pass http://127.0.0.1:3000;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection 'upgrade';
proxy_set_header X-Forwarded-For $remote_addr;
# First attempt to serve request as file, then
# as directory, then fall back to displaying a 404.
# try_files $uri $uri/ =404; }
Assuming 3000 port so this is a node.js application but still there should be files which i can access and do a backup.
Thanks