Nginx: cache and resize files

gistfile1.txt

server {
 location /resize {
   gzip on;
   gzip_static on;
   gzip_http_version 1.1;
   gzip_vary on;
   gzip_comp_level 1;
   gzip_proxied any;
   gzip_buffers 128 32k; #my pagesize is 4
   gzip_disable "MSIE [1-6]\.(?!.*SV1)";
   gzip_min_length 1000;
   gzip_types      *;
  expires 30d;
 access_log /dev/null;
  alias /tmp/nginx/resize;
  if ($uri ~* "^/resize_(\d+)x(\d+)/(.*)" ) {
          set $width  $1;
          set $height $2;
          set $image_path $3;
          set $quality 100;
          set $dimens "_$1x$2";
  }

  if ($uri ~* "^/resize/(.*)" ) {
    set $image_path $1;
  }

  set $image_uri image_resize/$image_path?width=$width&height=$height&quality=$quality;
  resolver 8.8.8.8;
  if (!-f $request_filename) {
      proxy_pass $scheme://127.0.0.1/$image_uri;
      break;
  }
    proxy_cache_valid 200 30d;
    proxy_cache_valid any 1m;
    proxy_store          /tmp/nginx/resize$dimens/$image_path;
    proxy_store_access   user:rw  group:rw  all:r;
    proxy_temp_path      /tmp/images;
    proxy_set_header     Host $host;
}

  location /image_resize {
      alias ###ROOT DIRECTORY HERE###;
      image_filter resize $arg_width $arg_height;
      break;
  }
}