Passing all Custom Headers to Proxy Pass in Nginx

Follow these steps

1. Inside server block -> use underscores_in_headers on;

2. Inside location block -> use proxy_pass_request_headers on;

Here is one example below. My UI server is hosted at / and backend server is behind /api/

Here is the nginx.conf file snippet

server {
         listen       80 ;
         server_name  localhost;
         client_max_body_size 200M;
         underscores_in_headers on;
         keepalive_timeout  1500;
 
         location ~* /api/ {          
             proxy_pass http://localhost:8080;
             proxy_pass_request_headers      on;
         }
         location / {          
             proxy_pass http://localhost:5173;
             proxy_pass_request_headers      on;
         }
 
     }