Takky, an asynchronous image/file attachment gem

Takky aims to make uploading, storing, and processing file attachments more transparent and robust than existing file management gems. It works best in asynchronous environments using Sidekiq, but it also supports synchronous uploads to Amazon S3.

Features

All uploads are performed in Sidekiq jobs, which allows you to utilize background processing and Sidekiq's retry queue for when things go awry
Minimal metaprogramming -- everything is plain old Ruby code where possible
Simple to read source code (if not, file a bug!)
While you can create multiple attachment models, we encourage you to use a single table for all attachments and add additional metadata via another model.

Impetus

At The Clymb, images are a core component of our site. We started with Paperclip in the beginning, but overtime, we accumulated a lot of cruft and have outgrown Paperclip. We implemented a new file attachment solution for a few reasons:

We are heavy users of Sidekiq and rely on it for handling third-party failures with automatic job retries. When S3 is down or your system's struggling to keep up with ImageMagick, it is desirable to have upload and processing jobs tracked and retried appropriately. Adding background processing capabilities to Paperclip and Carrierwave requires additional gems that aren't part of the main project, and we didn't want to add unnecessary complexity -- we want background processing to be a first-class citizen.
Some upload operations are best performed asynchronously -- the user may not need to wait around for the upload to complete, or the compositing operations can happen in the background.
Unlike Paperclip and the like, adding an attachment does not involve adding four columns to your model when you "attach" a file. Takky will require one foreign key on the model that references an attachments table. While you sacrifice initial convenience, requiring attachments to be stored separately out of the box prevents you from having models with 44 columns for 11 attachments, for example.

Finally, after spending many hours debugging one line methods, tiny classes, and gratuitous metaprogramming in other attachment gems, we want to emphasize clear and concise source code in Takky.

Installation

Add this line to your application's Gemfile:

gem "takky"

And then execute:

% bundle

Usage

First, configure Takky for your app, e.g., in a Rails initializer like config/initializers/takky.rb:

# Takky will reuse AWS configuration, but your app must execute the
# following somewhere, or you must have defined the environment
# variables listed here: http://docs.aws.amazon.com/AWSSdkDocsRuby/latest//DeveloperGuide/prog-basics-creds.html
#
#  AWS.config({
#    access_key_id:      s3_credentials['access_key_id'],
#    secret_access_key:  s3_credentials['secret_access_key']
#  })

Takky.configure do |c|
  c.src_host = 's3.amazonaws.com/bucket'
  c.cdn_host = 'cdn.example.com'
end

Bugs? Features?