How to configure nginx to redirect requests to the uploads directory to the production server?

I’m just getting my feet wet with nginx. In the past I’ve used an .htaccess file in /wp-content/uploads so if my dev or staging server doesn’t have the file it redirects to the production server:

<IfModule mod_rewrite.c>
  RewriteEngine On

  RewriteBase /wp-content/uploads/
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*) http://production.server.com/m/wp-content/uploads/$1 [L,P]

</IfModule>

I’m not having luck with doing this in nginx. It may be in part because this particular time my site is in a subdirectory (/m/).

# Tells nginx which directory the files for this domain are located
root         /srv/www/example/htdocs;
index               index.php;

    # Subdirectory location settings

    location /m {
            index index.php;
            try_files $uri $uri/ /m/index.php?$args;
            location /m/wp-content/uploads {
                    try_files $uri $uri/ @prod_svr;
            }
    }
    location @prod_svr {
            proxy_pass http://production.server.com/m/wp-content/uploads$uri;
    }

Any ideas would be greatly apprciated.

You could try something like this:

server {
    root /srv/www/example/htdocs;
    index index.php;

    # Matches any URL containing /wp-content/uploads/    
    location ~ "^(.*)/wp-content/uploads/(.*)$" {
        try_files $uri @prod_serv;
    }

    # Will redirect requests to your production server
    location @prod_serv {
        rewrite "^(.*)/wp-content/uploads/(.*)$" "http://yourdomain.com/m/wp-content/uploads/$2" redirect;
    }

    # The rest of your location blocks...
    location /m {
        index index.php;
        try_files $uri $uri/ /m/index.php?$args;
    }
}