Using ruby tempfile to fetch a remote resource for custom formatting

temp.rb

class LocalResource
  attr_reader :uri
  
  def initialize(uri)
    @uri = uri
  end

  def file
    @file ||= Tempfile.new(tmp_filename, tmp_folder, encoding: encoding).tap do |f|
      io.rewind
      f.write(io.read)
      f.close
    end
  end

  def io
    @io ||= uri.open
  end

  def encoding
    io.rewind
    io.read.encoding
  end

  def tmp_filename
    [
      Pathname.new(uri.path).basename,
      Pathname.new(uri.path).extname
    ]
  end

  def tmp_folder
    # If we're using Rails:
    Rails.root.join('tmp')
    # Otherwise:
    # '/wherever/you/want'
  end
end

def local_resource_from_url(url)
  LocalResource.new(URI.parse(url))
end


# URL is provided as input
url = 'https://s3.amazonaws.com/your-bucket/file.gif'
begin
  # We create a local representation of the remote resource
  local_resource = local_resource_from_url(url)
  # We have a copy of the remote file for processing
  local_copy_of_remote_file = local_resource.file
  # Do your processing with the local file
  `some-command-line-utility #{local_copy_of_remote_file.path}`
ensure
  # It's good idea to explicitly close your tempfiles
  local_copy_of_remote_file.close
  local_copy_of_remote_file.unlink
end

Blog post from http://viget.com/extend/make-remote-files-local-with-ruby-tempfile