location ^~ /dir1/ {
    rewrite ^(.*)$ /feed.php;

  }
  location ^~ /dir2/ {
    rewrite ^(.*)$ /feed.php;

  }
  location ^~ /dir3/ {
    rewrite ^(.*)$ /feed.php;

  }

 location = /feed.php {
         try_files $uri =404;
         include fastcgi_params;
         fastcgi_read_timeout 9400;
         fastcgi_pass php:5555;
         fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
 }