This script generates two simple daemons to process images with convert and uploads them to S3.

image_processing_daemon.rb

# Image processing daemons
# By VvanGemert
#
# Requirements:
# apt-get install imagemagick
# ruby 1.9.3 or higher
# gem install daemons
# gem install aws-s3
#
# Usage:
# ruby image_processing_daemon.rb start|stop|restart

require 'rubygems'
require 'daemons'
require 'fileutils'
require 'aws/s3'

## SETTINGS

PHOTO_PATH = "/uploaded/photos/path/"
RESULT_PATH = "/temporary/photos/results/path"

AWS::S3::Base.establish_connection!(
  :access_key_id     => 'XXXXX',
  :secret_access_key => 'XXXXX'
)

BUCKET = "bucket.amazon.com"
BUCKET_PATH = "bucket/path"

CONVERSION = {
  :thumb => "convert -size 132x132 :file -thumbnail 132x132^ -gravity center -extent 132x132 :fullpath_thumb.jpg",
  :default => "convert -resize 800x600^ :file :fullpath.jpg",
  :original => "convert :file :fullpath_original.jpg"
}


## SETTINGS

Daemons.run_proc('resizing.rb') do
  loop do
    images = Dir[PHOTO_PATH + "*/*"]
    images.each do |file|
     base = File.basename(file,File.extname(file))
     Dir.mkdir(RESULT_PATH) unless File.directory?(RESULT_PATH)
     full_path = RESULT_PATH + "/" + base
     map = {':file' => file, ':fullpath' => full_path}
     CONVERSION.each do |key,str|
       map.each {|k,v| str.sub!(k,v)}
       system(str)
     end
     FileUtils.rm(file)
    end
    sleep(2)
  end
end

Daemons.run_proc('s3sync.rb') do
  loop do
    images = Dir[RESULT_PATH + "*/*"]
    images.each do |file|
      base = File.basename(file)
      AWS::S3::S3Object.store(BUCKET_PATH, File.open(file).read, BUCKET, :access => :public_read)
      FileUtils.rm(file)
    end
    sleep(2)
  end
end