$request_filename

Description

The $request_filename variable in NGINX is set during the processing of a request and provides the complete filesystem path to the requested resource. It is constructed based on the request URI and the specified root or alias directives in the configuration. When a request is made, NGINX combines the root path defined in the relevant context with the URI, resulting in the absolute path on the server where the requested file or directory can be found. For example, if a request is made for '/images/logo.png' and the server block’s root is set to '/var/www/html', then $request_filename would be '/var/www/html/images/logo.png'. This variable is particularly useful for modules that require file access, such as handling static files, enabling custom logging formats, or implementing conditional logic with the `try_files` directive. $request_filename gets re-evaluated for each request context, ensuring it reflects the current request’s target accurately. Common use cases include logging the requested file path or checking its existence before performing further processing with `try_files` or other configuration directives.

Config Example

location /images/ {
    root /var/www/html;
    if (!-f $request_filename) {
        return 404;
    }
}