Nginx map doesn't use the arguments of my regular expression - nginx

Question

I'm trying to use the map of nginx, but the results aren't what I expect.
This is what I have:
map $uri $new {
default "";
~*/cc/(?P<suffix>.*)$ test.php?suffix=$suffix;
}
location ~ [a-zA-Z0-9/_]+$ {
proxy_pass http://www.domain.com:81/$new;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;
proxy_set_header X-Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
When I go to www.domain.com/cc/abc, I see this in the logs
2012/03/29 17:27:53 [warn] 3382#0: *33 an upstream response is buffered to a temporary file /var/cache/nginx/proxy_temp/5/00/0000000005 while reading upstream, client: 1.2.3.4, server: www.domain.com, request: "GET /cc/abc HTTP/1.1", upstream: "http://1270.0.0.1:81/test.php?suffix=$suffix", host: "www.domain.com"
The $suffix isn't replaced.
But when I do this:
map $uri $new {
default "";
~*/cc/(?P<suffix>.*)$ $suffix;
}
location ~ [a-zA-Z0-9/_]+$ {
proxy_pass http://www.domain.com:81/$new;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;
proxy_set_header X-Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
And now, when I go to go to www.domain.com/cc/abc, the logs show me this:
2012/03/29 17:29:39 [warn] 5916#0: *26 an upstream response is buffered to a temporary file /var/cache/nginx/proxy_temp/2/00/0000000002 while reading upstream, client: 1.2.3.4, server: www.domain.com, request: "GET /cc/abc HTTP/1.1", upstream: "http://1270.0.01:81/abc", host: "www.domain.com"
So, when the rewrite contains a string including the variable, it isn't replaced. But if it only contains the variable, it will work.
What am I doing wrong?

Answer 1

As you've discovered, map replacements can only be a static string or a single variable. Since test.php?suffix=$suffix doesn't start with a $, nginx assumes it's just a static string. Instead of using a map, you'll need to use two rewrites to accomplish what you want:
location ~ [a-zA-Z0-9/_]+$ {
rewrite ^/cc/(.*) /test.php?suffix=$1 break;
rewrite ^ / break;
proxy_pass http://www.domain.com:81;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;
proxy_set_header X-Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
The first rewrite will strip any initial /cc/ from the url and append the rest as the url arg like your map was trying to. The break flag tells nginx to stop processing rewrite directives. If the first rewrite doesn't match, then the second will always match, and will set the url to /.
EDIT: As of 1.11.0, map values can be complex values, so the original config would work