Issue when using "add" with X-Forwarded-Proto header

[utopiandreams]

After applying NGF, I encountered a CORS issue. When checking the configuration in the NGINX container, I found a difference compared to my previous NGINX setup.

        proxy_set_header` X-Forwarded-Proto $scheme;

Previously, I was using the above setting to add the scheme information to the X-Forwarded-Proto header and forward it to the backend. However, I noticed that this part was missing from the current configuration. I suspect that the CORS issue occurred because the protocol was not properly forwarded to the backend. To solve this, I tried adding the header using the RequestHeaderModifier filter, and the problem was resolved (I noticed that using the $ character to directly use variables was not possible).

     filters:
       - type: RequestHeaderModifier
         requestHeaderModifier:
           set:
             - name: X-Forwarded-Proto
               value: https

However, I don't feel comfortable using a hardcoded string, so I tried modifying the configuration slightly. When I used the add tag, it automatically created a ${} block and appended the protocol followed by the tag I set.

       proxy_set_header X-Forwarded-Proto "${x_forwarded_proto_header_var}https";



       map ${http_x_forwarded_proto} $x_forwarded_proto_header_var {
          default '';
          ~.* ${http_x_forwarded_proto},;
        } 

I want to know how I can configure it so that only ${x_forwarded_proto_header_var} remains, without adding any extra strings or values. I thought I could use an empty string with add, but it turned out to be an invalid value, so it was not applied. How can I achieve this?

[kate-osborn]

@utopiandreams we recently added the X-Forwarded-Proto: $scheme header to the base nginx configuration: https://github.com/nginxinc/nginx-gateway-fabric/blob/1241d101314b535192b89e1114965c0a52064388/internal/mode/static/nginx/config/servers.go#L49.

So we now add the following headers by default to all location blocks:

      proxy_set_header Host "$gw_api_compliant_host";
      proxy_set_header X-Forwarded-For "$proxy_add_x_forwarded_for";
      proxy_set_header Upgrade "$http_upgrade";
      proxy_set_header Connection "$connection_upgrade";
      proxy_set_header X-Real-IP "$remote_addr";
      proxy_set_header X-Forwarded-Proto "$scheme";
      proxy_set_header X-Forwarded-Host "$host";
      proxy_set_header X-Forwarded-Port "$server_port";

These changes are in the edge version if you want to try them and see if they fix your problem.

[utopiandreams]

Oh wow. Thank you so much for your helpful response. I'll make sure to keep using NGF !