Portable nginx reverse proxy with CORS override

nginx.conf

#!/usr/bin/env -S nginx -e /dev/stderr -p . -c
# Run an NGINX instance serving the current directory on ports 8080 and 8443
# (when configured). Execute one of the following commands in the terminal.
# - start-nodaemon: ./nginx.conf -g 'daemon off;'
# - start:          ./nginx.conf
# - stop:           ./nginx.conf -s stop
# - reload:         ./nginx.conf -s reload
pid .nginx/nginx.pid;

events {}
http {
	include /etc/nginx/mime[.]types; # Linux
	include /usr/local/etc/nginx/mime[.]types; # OSX/homebrew
	default_type application/octet-stream;
	types {
		application/javascript mjs;
	}

	access_log .nginx/http.access.log;
	error_log .nginx/http.error.log;

	client_body_temp_path .nginx/client_body;
	fastcgi_temp_path .nginx/fastcgi;
	proxy_temp_path .nginx/proxy;
	scgi_temp_path .nginx/scgi;
	uwsgi_temp_path .nginx/uwsgi;

	# Set the Content-Length header for OPTIONS requests
	map $request_method $override_content_length { default ''; OPTIONS 0; }

	ssl_protocols TLSv1.3;
	server {
		root .;
		listen 8080;
		listen [::]:8080;

		# Be sure to generate the necessary certificates before enabling SSL:
		#
		#	openssl req -new -x509 -days 7300 -nodes -newkey rsa:2048 -out \
		#		 .nginx/snakeoil.pem -keyout .nginx/snakeoil.key -subj \
		#		 "/C=ZZ/O=Snakeoil Cert"
		#listen 8443 ssl;
		#listen [::]:8443 ssl;
		#ssl_certificate .nginx/snakeoil.pem;
		#ssl_certificate_key .nginx/snakeoil.key;


		location /api/ {
	        proxy_pass https://example.com/;
	        proxy_ssl_server_name on;
	        proxy_set_header X-Real-IP $remote_addr;
	        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
	        proxy_set_header X-Forwarded-Proto $scheme;

	        # CORS headers
	        add_header 'Access-Control-Allow-Origin' 'https://localhost:3000' always;
	        add_header 'Vary' 'origin' always;
	        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS, PUT, DELETE' always;
	        add_header 'Access-Control-Allow-Headers' 'Authorization, Content-Type, Accept, Origin, X-Requested-With' always;
	        add_header 'Access-Control-Allow-Credentials' 'true' always;

	        # Handle CORS preflight requests
	        if ($request_method = 'OPTIONS') {
	            add_header 'Access-Control-Max-Age' 1728000;
	            add_header 'Content-Type' 'text/plain charset=UTF-8';
	            add_header 'Content-Length' 0;
	            return 204;
	        }
	    }
	}
}

# source: https://gist.github.com/webstrand/2389c00cb7a5418ac0119e3451a97056
# CORS rules source: https://michielkalkman.com/snippets/nginx-cors-open-configuration/