Deploying Client and Server to the same VM - reactjs

Question

I have an application that has a React frontend and a Python Flask backend. The frontend communicates with the server to perform specific operations and the server api should only be used by the client.
I have deployed the whole application (Client and Server) to an Ubuntu virtual machine. The machine only has specific ports open to the public (5000, 443, 22). I have setup Nginx configuration and the frontend can be access from my browser via http://<ip:address>:5000. The server is running locally on a different port, 4000, which is not accessible to the public as designed.
The problem is when I access the client app and I navigate to the pages that communicate with the server via http://127.0.0.1:4000 from the react app, I get an error saying connection was refused.
GET http://127.0.0.1:4000/ net::ERR_CONNECTION_REFUSED on my browser.
When I ssh into the vm and run the same command through curl curl http://127.0.0.1:4000/, I get a response and everything works fine.
Is there a way I can deploy the server in the same vm such that when I access the client React App from my browser, the React App can access the server without problems?

Answer 1

So after tinkering with this, I found a solution using Nginx. Summary is you run the server locally and use a different port say 4000 (not exposed to public), then expose your react app on the exposed port in this case 5000.
Then use a proxy in your Nginx config that redirects any call starting with api to the local host server running. See config below
server {
#Exposed port and servername ipaddress
listen 5000;
server_name 1.2.3.4 mydomain.com;
#SSL
ssl on;
ssl_certificate /etc/nginx/ssl/nginx.crt;
ssl_certificate_key /etc/nginx/ssl/nginx.key;
ssl_protocols TLSv1.2;
#Link to the react build
root /var/www/html/build;
index index.html index.htm;
#Error and access logs for debugging
access_log /var/log/nginx/access.log;
error_log /var/log/nginx/error.log;
location / {
try_files $uri /index.html =404;
}
#Redirect any traffic beginning with /api to the flask server
location /api {
include proxy_params;
proxy_pass http://localhost:4000;
}
}
Now this means you need to have all your server endpoints begin with /api/... and the user can also access the endpoint from the browser via http://<ip:address>:5000/api/endpoint
You can mitigate this by having your client send a token the server and the server will not run any commands without that token/authorization.
I found the solution here and modified it to fit my specific need here
Part two of solution
Other series in the solution can be found Part one of solution and Part three of solution