Logging POST data from $request_body

[barretto_chris]

I have my config setup to handle a bunch of GET requests which render
pixels that work fine to handle analytics and parse query strings for
logging. With an additional third party data stream, I need to handle a
POST request to a given url that has JSON in an expected loggable format
inside of it's request body. I don't want to use a secondary server with
proxy_pass and just want to log the whole response into an associated
log file like what it does with GET requests. A snippet of some code
that I'm using looks like the following:

GET request (which works great):
  [code]
location ^~ /rl.gif {
    set $rl_lcid $arg_lcid;
    if ($http_cookie ~* "lcid=(.*\S)")
    {
      set $rl_lcid $cookie_lcid;
    }

    empty_gif;
    log_format my_tracking '{ "guid" : "$rl_lcid", "data" :
"$arg__rlcdnsegs" }';
    access_log  /mnt/logs/nginx/my.access.log my_tracking;
    rewrite ^(.*)$ http://my/url?id=$cookie_lcid? redirect;
  }
[/code]

Here is kinda what I am trying to do:
POST request (which does not work):
  [code]
location /bk {
    log_format bk_tracking $request_body;
    access_log  /mnt/logs/nginx/bk.access.log bk_tracking;
  }
[/code]

Curling "curl http://myurl/bk -d name=example" gives me a 404 page not
found.

Then I tried:
  [code]
location /bk.gif {
    empty_gif;
    log_format bk_tracking $request_body;
    access_log  /mnt/logs/nginx/bk.access.log bk_tracking;
  }
[/code]
Curling "curl http://myurl/bk.gif -d name=example" gives me a 405 Not
Allowed.

My current version is nginx/0.7.62. Any help in the right direction is
very much appreciated! Thanks!

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,173356,173356#msg-173356