How can I use wildcards in an Nginx map directive?
- by Ian Clelland
I am trying to use Nginx to served cached files produced by a web application, and have spotted a potential problem; that the url-space is wide, and will exceed the Ext3 limit of 32000 subdirectories.
I would like to break up the subdirectories, making, say, a two-level filesystem cache. So, where I am currently caching a file at
/var/cache/www/arbitrary_directory_name/index.html
I would store that instead at something like
/var/cache/www/a/r/arbitrary_directory_name/index.html
My trouble is that I can't get try_files, or even rewrite to make that mapping. My searching on the subject leads me to believe that I need to do something like this (heavily abbreviated):
http {
map $request_uri $prefix {
/aa* a/a;
/ab* a/b;
/ac* a/c;
...
/zz* z/z;
}
location / {
try_files /var/cache/www/$prefix/$request_uri/index.html @fallback;
# or
# if (-f /var/cache/www/$prefix/$request_uri/index.html) {
# rewrite ^(.*)$ /var/cache/www/$prefix/$1/index.html;
# }
}
}
But I can't get the /aa* pattern to match the incoming uri. Without the *, it will match an exact uri, but I can't get it to match just the first two characters.
The Nginx documentation suggests that wildcards should be allowed, but I can't see a way to get them to work. Is there a way to do this? Am I missing something simple? Or am I going about this the wrong way?
