Strange results when chaining try_files

[Jeff Waugh]

Hi all,

Wondering if anyone can explain what's going on here... I'm trying to come
up with a "more perfect" WordPress + WP-Super-Cache configuration, using
try_files to fall back through static files, cached files and finally, the
dynamic script... the challenge is the preconditions on the use of the on
disk cached files (checking cookies and so on).

Here's a summary of the virtual host's configuration:

  server {
    listen  80;
    server_name  trunk.press.home;
    root  /srv/wordpress/trunk;
    index  index.php;

    access_log  /var/log/nginx/access.log;
    error_log  /var/log/nginx/error.log  notice;
    rewrite_log  on;

    location / {
      try_files  $uri  @supercache;
      # ultimately this would have more in it, but I have
      # stripped it down to clarify the test case
    }

    location @supercache {
      set  $idx  'index.html';
      set $supercache '/wp-content/cache/supercache/$host$request_uri$idx';
      # ^ nasty, but it's because I can't do $request_uriindex.html :-)

      if ( $http_cookie ~* wordpress ) {
        set  $supercache  '';
        break;
      }

      try_files  $supercache  /index.php;
    }

    location ~ \.php$ {
      # totally normal, working fastcgi configuration
    }
  }

A no-cookie request to http://trunk.press.home/ and /about/ works fine. A
request to / with the cookie works fine. However, a request to /about/ with
the cookie returns a 404.

Here's what the logs show:

  [notice] 28051#0: *21690 "wordpress" matches "wordpress=true", client:
  192.168.10.121, server: trunk.press.home, request: "GET /about/ HTTP/1.1",
  host: "trunk.press.home"

  [error] 28051#0: *21690 "/srv/wordpress/trunk/about/index.php" is not
  found (2: No such file or directory), client: 192.168.10.121, server:
  trunk.press.home, request: "GET /about/ HTTP/1.1", host:
  "trunk.press.home"

It's that second error which surprises me -- why, with the cookie, is the
ultimate request going to /trunk/about/index.php, not /trunk/index.php? AND,
if I change the index to index.html, it'll fail looking for THAT (ie. this
is not a result of the try_files in @supercache).

This fails even if I set $supercache to a nonsense file rather than a blank
string.

Thoughts?

- Jeff

-- 
linux.conf.au 2010: Wellington, NZ                http://www.lca2010.org.nz/
 
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