gem 'rack-large-uploads'

$ bundle

$ gem install rack-large-uploads

use Rack::LargeUploads do
  before do |files|
    # process uploaded files *before* application handling
  end

  after do |files|
    # process uploaded files *after* application handling
  end
end

location / {
  try_files $document_root/system/maintenance.html $uri $uri/index.html $uri.html @application;
}

location = /uploads {
  # depends on the nginx upload module (http://www.grid.net.ru/nginx/upload.en.html)
  upload_pass         @application;

  # NOTE: if the request is something other than POST, nginx generates a 405.
  # use that to pass the request on to the endpoint, instead of try_files
  # which fails to play nicely with upload_pass.
  #
  # credit:
  # http://www.nickager.com/blog/File-upload-using-Nginx-and-Seaside---step-1
  error_page          405 415 = @application;

  # NOTE: cleaning up 201 & 202 means we need to be sure our app is doing
  # some processing right away. Rack::LargeUploads sends 202 responses for
  # each chunk received during chunked uploads, and the chunk has been
  # appended to the combined file by the time we're back with the response.
  upload_cleanup      201 202 400 404 499 500-505;
  upload_store        /path/to/app/tmp/uploads 1;
  upload_store_access user:rw group:rw all:rw;

  upload_pass_args       on;          # NOTE: handles URI params, not form content.
  upload_pass_form_field "^[a-z_].*"; # ...and here is how we resolve that last.

  # match the request params expected by ActionDispatch
  upload_set_form_field "$upload_field_name[filename]"   "$upload_file_name";
  upload_set_form_field "$upload_field_name[type]"       "$upload_content_type";
  upload_set_form_field "$upload_field_name[tempfile]"   "$upload_tmp_path";

  upload_aggregate_form_field "$upload_field_name[md5]"  "$upload_file_md5";
  upload_aggregate_form_field "$upload_field_name[size]" "$upload_file_size";
}

location @application {
  proxy_pass  http://upstream_application;

  # more config...
}