How to do it...

To enable, we map the ($args) URI arguments to a $debuglogs variable, based on if a condition is set. Here's the code:

map $args $debuglogs { 
    default     0; 
    debug       1; 
} 

Like the custom log formats, this needs to be placed outside of the server directives. Then, within the server directive, we can make use of the variable and create additional logging:

access_log /var/log/nginx/djangodemo-debug-access.log applogs if=$debuglogs; 
access_log  /var/log/nginx/djangodemo-access.log  combined; 

If we call a normal URL, it will simply log the access to the standard djangodemo-access.log in the combined format. If we call a URL with the debug argument set (for example: http://djangodemo.nginxcookbook.com/?debug), we now get the details logged in both the standard logs as well as our additional djangodemo-debug-access.log using the applogs format we defined in the previous recipe.