Opened 5 years ago

Last modified 3 years ago

#803 closed enhancement

proxy_pass differs in behavior if used with variable substitution — at Initial Version

Reported by: s3tqr2w@… Owned by:
Priority: minor Milestone:
Component: documentation Version: 1.8.x
Keywords: docs Cc:
uname -a: Linux nginx 3.10.0-229.14.1.el7.x86_64 #1 SMP Tue Sep 15 15:05:51 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
nginx -V: nginx version: nginx/1.8.0
built by gcc 4.8.2 20140120 (Red Hat 4.8.2-16) (GCC)
built with OpenSSL 1.0.1e-fips 11 Feb 2013
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --user=nginx --group=nginx --with-http_ssl_module --with-http_realip_module --with-http_addition_module --with-http_sub_module --with-http_dav_module --with-http_flv_module --with-http_mp4_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_random_index_module --with-http_secure_link_module --with-http_stub_status_module --with-http_auth_request_module --with-mail --with-mail_ssl_module --with-file-aio --with-ipv6 --with-http_spdy_module --with-cc-opt='-O2 -g -pipe -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic'

Description

This may be desired, but it is not well documented, and caused me many hours of troubleshooting.

if using no-variables the uri is implicitly and transparently appended to the proxy_pass, i.e. a static definition:

location /test/ {

proxy_pass http://upstream/test/;

}

Called with a URI of /test/this, will call the upstream URL: http://upstream/test/this. However, if a variable definition is used:

location /test/ {

set $upstream_var upstream;
proxy_pass http://$upstream_var/test/;

}

The same URL will ignore the URI, and only ever call http://upstream/test/

Changing the definition as follows resolves the problem, but is very counter-intuitive as the same command behaves differently which is not expected:

location /test/ {

set $upstream_var upstream;
proxy_pass http://$upstream_var$request_uri;

}

I don't know if there is a code fix to this--but it wasn't easy to figure out so perhaps the docs could somehow be more clear?

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