nginx cache + google cloud storage

nginx.conf

# The following url will be available :
# getting the original image : http://your-domain.tld/og/{bucketname}/{imagepath}
# sizing an image (here, will fit in a 200x200px area) : http://your-domain.tld/t/200x200/{bucketname}/{imagepath}

# important part : set the cache folder (here /tmp/nginx-images) and the cache name (here thumbnail_cache)
proxy_cache_path /tmp/nginx-images levels=1:2 keys_zone=thumbnail_cache:16M inactive=60d max_size=200M;

server {
    listen 80;
    server_name your-domain.tld;
    location / {
      proxy_pass http://localhost:10101;
      proxy_cache thumbnail_cache;
      proxy_cache_key "$host$document_uri$is_args$arg_key";
      proxy_cache_lock on;
      proxy_cache_valid 30d;  # Cache valid thumbnails for 30 days.
      proxy_cache_valid any 15s;
      proxy_cache_use_stale error timeout invalid_header updating;
      proxy_http_version 1.1;
      expires 30d;
    }
}
server {
  listen 10101;
  server_name localhost;
  set $backend 'storage.googleapis.com';
  resolver 8.8.8.8;
  resolver_timeout 5s;
  proxy_buffering off;
  proxy_http_version 1.1;
  proxy_pass_request_body off;
  proxy_pass_request_headers off;
  proxy_set_header Host $backend;
  proxy_method GET;
  image_filter_jpeg_quality 85;
  image_filter_buffer 12M;
  image_filter_interlace on;
  error_page 404 =404 /empty.gif;
  location ~ ^/og/(.*) {
    set $image_path '$1';
    image_filter_jpeg_quality 75;
    proxy_pass http://$backend/$1;
  }
  location ~ ^/t/([\d-]+)x([\d-]+)/(.*) {
    #http://stackoverflow.com/a/4243129
    #secure_link $arg_key;  # The hash is stored in the `key` querystring arg.
    #secure_link_md5 "$uri my-secret-key";
    #if ($secure_link = "") {
    #       return 404;
    #}
    set $image_path '$3';
    image_filter resize $1 $2;
    proxy_pass http://$backend/$3;
  }
}