simple nginx reverse proxy seems to strip some headers

Question

I am a beginner at nginx. I have a simple webserver on 8080 that I want to pass all traffic to in this rather small environment. My proxy seems to work except that a custom header is not there when it gets to my upstream server. The server block is below. What would I need to add to this to keep my custom header? In this case the custom header was set in angularjs but I don't think that has anything to do with it as it works fine going directly to 8080 on the server. ($httpProvider.defaults.headers.common['GH_client'] = client_id();)

server {
server_name localhost;

location / {
        proxy_pass      http://localhost:8080;
        proxy_redirect  off;
    proxy_pass_header X-CSRF-TOKEN;
        proxy_set_header   Host             $host;
        proxy_set_header   X-Real-IP        $remote_addr;
        proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
        proxy_set_header   X-NginX-Proxy true;
}}

Thanks for any help.

Answer 1

Your header contains underscore (_). By default, nginx treats headers with an underscore as invalid and drops them.

You should enable underscores_in_headers directive.

Otherwise, consider changing the header name to one without underscores. GH-client will be perfectly valid and proxied to your backend server.