How to proxy requests from nginx to an upstream backend. Could be use for Python or JavaScript (express) apps.

nginx.conf

http {
    # other stuff here

    # The upstream backend server this can be named whatever you desire
    # See http://nginx.org/en/docs/http/ngx_http_upstream_module.html
    upstream backend {
        # this is the actual hostname + port of the backend server
        server backend:8080;
        # how many keep alive connections to allow, only set this if you're going
        # to specify the `Connection` header in the proxy below, nginx sets the
        # proxy to "Connection: close" by default.
        keepalive 32; 
    }

    # the main entrypoint server
    server {
        server_name yourapp.example.com;
        listen      80;
        
        # maybe HTTPS stuff here too...

        # document root!
        root        /app/public;

        # this is the important bit! Try to load the request URI or fallback to the named
        # @backend location
        try_files   $uri @backend;
        
        # you may also want to do something like this if you have index files in your app
        # this will try the actual URI, then the URI as a directory, then fallback to
        # the backend location if those two don't work.
        # index index.html;
        # try_files $uri $uri/ @backend;

        # This is a "named" location (see http://nginx.org/en/docs/http/ngx_http_core_module.html#location)
        # it defines some proxy headers then pases the request to the upstream `backend` defined above
        location @backend {
            proxy_set_header Host $http_host;
            proxy_set_header Connection ""; # use keepalive connections
            proxy_set_header X-Forwarded-For $remote_addr; # pass the real IP
            # any other headers you may want!
            proxy_http_version 1.1;
            proxy_pass http://backend;
        }
    }
}