Use S3 (via the aws gem) in Rails to store user files such as images

aws.rb

# Place this file in config/initializers
# load the libraries
require 'aws'

# log requests using the default rails logger
AWS.config(:logger => Rails.logger)

# here's how to load credentials from a file
#config_path = File.expand_path(File.dirname(__FILE__)+"/../aws.yml")
#AWS.config(YAML.load(File.read(config_path)))

# we load credentials from the environment
AWS.config(:access_key_id => ENV['S3_KEY'])
AWS.config(:secret_access_key => ENV['S3_SECRET'])

user_assets_controller.rb

# Controller for storing and retrieving user assets, such as local files
class UserAssetsController < ApplicationController

  S3_BUCKET = 'your-user-assets-bucket-name'

  def put
    if params[:asset]
      s3 = AWS::S3.new
      bucket = s3.buckets[S3_BUCKET]
      obj = bucket.objects[s3_filename(params[:user_id], filename)]
      obj.write params[:image].tempfile
      render :text => obj.public_url
    else
      render :text => '{error}'
    end
  end

  def get
    s3 = AWS::S3.new
    bucket = s3.buckets[S3_BUCKET]
    obj = bucket.objects[s3_filename(params[:user_id], params[:filename])]
    #TODO - get the file type, send with :type => image.content_type
    send_data obj.read, :disposition => 'inline', :filename => params[:filename]
  end

  protected

  def s3_filename(user_id, filename)
    prefix = Rails.env.production? ? '' : "#{Rails.env}/"
    "#{prefix}#{CGI.escape(user_id)}/#{normalize_filename(filename)}"
  end

  # Make the original filename fit for storage on S3
  def normalize_filename(filename)
    filename
  end

end