Simple class to create a tmp local file from a url

local_resource.rb

require 'open-uri'

class LocalResource
  def initialize(_url, _tmp_filename)
    @uri = URI.parse(_url)
    @tmp_file_name = File.basename(_tmp_filename, ".*")
    @tmp_file_ext = File.extname(_tmp_filename)
  end

  def file
    filename = [@tmp_file_name, @tmp_file_ext]
    @file ||= Tempfile.new(filename, self.class.tmp_dir, encoding: encoding).tap do |f|
      io.rewind
      f.write(io.read)
      f.close
    end
  end

  def file_path
    file.path
  end

  def destroy
    return unless @file
    @file.delete
    @file = nil
  end

  def self.destroy_tmp_dir
    FileUtils.rm_rf(tmp_dir)
  end

  private

  def self.tmp_dir
    path = Rails.root.join('tmp/local_resources')
    FileUtils::mkdir_p(path.to_s).first
  end

  def encoding
    io.read.encoding
  end

  def io
    @io ||= @uri.open
  end
end

# Usage

resource = LocalResource.new("http://lorempixel.com/50/50/", "my-file.png")
resource.file_path # to get the file location
resource.destroy # to delete after use