id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
2543	"wrong ""host"" header when using upstreams"	girsch.ventx.de@…		"Hi,

we have a reverse proxy setup with 2 upstreams, the decision to which upstream to route a request is based on value of a specific header.
Lets say we want to route requests to upstreams based on a value of the user-agent header


{{{
          upstream banana {
             server banana-server;
           }
           upstream apple {
             server apple-server;
           }

          map $http_user_agent $proxied_server {
            default apple;

            ""~*Firefox*"" apple;
            ""~*Chrome*"" banana;
          }
 
          server {
              listen 8080;
              server_name localhost;
              location / {
                    proxy_pass http://$proxied_server;
              }
          }
}}}


the request is sent to the right upstream IP by a reverse proxy, but instead of taking the DNS name of the server specified in the ""upstream"" the reverse proxy takes the name of upstream as a value for the host header. So instead of ""banana-server"" it sends just ""banana"". "	defect	closed	minor		nginx-core	1.24.x	invalid			Linux reverse-proxy-nginx-69666dccb-mbnfn 5.15.128-1-MANJARO #1 SMP PREEMPT Sat Aug 26 17:22:47 UTC 2023 x86_64 GNU/Linux	"$ nginx -V
nginx version: nginx/1.24.0
built with OpenSSL 1.1.1n  15 Mar 2022
TLS SNI support enabled
configure arguments: --prefix=/opt/bitnami/nginx --with-http_stub_status_module --with-stream --with-http_gzip_static_module --with-mail --with-http_realip_module --with-http_stub_status_module --with-http_v2_module --with-http_ssl_module --with-mail_ssl_module --with-http_gunzip_module --with-threads --with-http_auth_request_module --with-http_sub_module --with-http_geoip_module --with-compat --with-stream_realip_module --with-stream_ssl_module --with-cc-opt=-Wno-stringop-overread --add-module=/bitnami/blacksmith-sandox/nginx-module-vts-0.2.2 --add-dynamic-module=/bitnami/blacksmith-sandox/nginx-module-geoip2-3.4.0 --add-module=/bitnami/blacksmith-sandox/nginx-module-substitutions-filter-0.20220124.0 --add-dynamic-module=/bitnami/blacksmith-sandox/nginx-module-brotli-0.20220429.0"