Use AWS-SDK to Migrate Paperclip Attachments from Files to S3

migrate_to_s3.rake

# Create config/s3.yml
# Example:
#   development:
#     bucket: electric-images
#     access_key_id: AKIAJADQBJZ4GTP4FY7A
#     secret_access_key: CKu9iYpFZoLRfr9zadtDRUA3BYUUWmnghyy2AJrg
#     region: ap-southeast-1 #Change this



namespace :attachments do  
  desc "migrate files from filesystem to s3"
  task :migrate_to_s3 => :environment do
    require 'aws/s3'
 
    # Load credentials
    s3_options = YAML.load_file(File.join(Rails.root, 'config/s3.yml'))[Rails.env].symbolize_keys
    bucket = s3_options[:bucket]
    
    # Establish S3 connection
    s3_options.delete(:bucket)
    s3 = AWS::S3.new(:access_key_id => s3_options[:access_key_id], :secret_access_key => s3_options[:secret_access_key], :region => s3_options[:region])
    #AWS::S3::Base.establish_connection!(s3_options)

    
    # determine the models to migrate
    klasses = ["Spree::Image"]
    
    klasses.each do |klass_sym|
      if @klass = real_klass(klass_sym)
        if @klass.respond_to?(:attachment_definitions) && definitions = @klass.attachment_definitions
          
          total_items  = @klass.count
          current_item = 1
          
          @klass.all.each do |record|
            definitions.each_pair do |column, value|
              attachment = record.send(column.to_sym)
              
              # NOTE: If the application is configured to use S3 already, 
              # calling exists? won't work as expected because paperclip will automatically look on Amazon.
              if !attachment.exists?
                total_items -= 1
                next
              end
              
              styles = value[:styles].keys rescue []
              styles.push(:original)
              
              styles.each do |style|
                
                # whatever mapping needed to where your files will live on S3
                # in my case, I changed the URL when migrating to S3
                path = attachment.url(style.to_sym).gsub('/system/files', '') #Change this to whatever is relevant to your paths
                file = attachment.path(style.to_sym)
                
                # skip if we already have this file on S3
                #next if AWS::S3::S3Object.exists?(path, bucket)
                next if s3.buckets[bucket].objects[path].exists?

                
                begin
                  print "uploading: #{style.to_sym}..."
                  s3.buckets["electric-images"].objects[path].write(:file => file) 
                  #AWS::S3::S3Object.store(path, file, bucket, :access => :public_read)
                  print " done.\n"
                rescue Exception => e
                  puts e.inspect
                end
              end
              
              # fancy output
              percent_complete = ((current_item.to_f / total_items.to_f) * 100).round(2)
              
              puts "Completed: #{current_item} / #{total_items}: ~#{percent_complete}%"
              
              current_item += 1
            end
          end
          
        else
          puts "There are no paperclip attachments defined for: #{@klass.to_s}"
        end
      else
        puts "#{klass_sym.to_s.classify} is not an existing model."
      end
    end
  end
  
  def real_klass(key)
    key.to_s.classify.constantize
  rescue
  end
end

Run with rake attachments:migrate_to_s3