Upload public images to Amazon S3

upload_assets.rake

require 's3'
require 'digest/md5'
require 'mime/types'

## These are some constants to keep track of my S3 credentials and
## bucket name. Nothing fancy here.

AWS_ACCESS_KEY_ID = ENV["AWS_ACCESS_KEY_ID"]
AWS_SECRET_ACCESS_KEY = ENV["AWS_SECRET_ACCESS_KEY"]
AWS_BUCKET = ENV["AWS_S3_BUCKET"]

## This defines the rake task `assets:deploy`.
namespace :assets do
  desc "Deploy all matching assets in public/**/* to S3/Cloudfront"
  task :deploy => :environment do |t, args|#, :env, :branch do |t, args|

## Use the `s3` gem to connect my bucket
    puts "== Uploading assets to S3/Cloudfront"

    service = S3::Service.new(
      :access_key_id => AWS_SECRET_ACCESS_KEY,
      :secret_access_key => AWS_SECRET_ACCESS_KEY)

    bucket = service.buckets.find(AWS_BUCKET)

## Needed to show progress
    STDOUT.sync = true

## Get all images in the image model, check their URLs, and upload only them

    ## Looping through images in the DB
    images = Image.all
    images.each do |image|
      file = Dir["#{Rails.root}/public#{image.image.url}"].first
      remote_file = "#{image.image.url}"
      remote_file = remote_file.gsub("/uploads/", "uploads/")

      if file
        ## Only upload files, we're not interested in directories
        if File.file?(file)

          ## Try to find the remote_file, an error is thrown when no
          ## such file can be found, that's okay.
          begin
            obj = bucket.objects.find_first(remote_file)
          rescue
            obj = nil
          end

          ## If the object does not exist, or if the MD5 Hash / etag of the
          ## file has changed, upload it.
          if !obj || (obj.etag != Digest::MD5.hexdigest(File.read(file)))
              print "U"

              ## Simply create a new object, write the content and set the proper
              ## mime-type. `obj.save` will upload and store the file to S3.
              obj = bucket.objects.build(remote_file)
              obj.content = open(file)
              obj.content_type = MIME::Types.type_for(file).to_s

              obj.save
          else
            print "."
          end
        end
      end
    end
     STDOUT.sync = false # Done with progress output.

    puts
    puts "== Done syncing assets"
  end
end