gistfile1.rb

require 'net/http/post/multipart'

def file=(_file)
  url = URI.parse(<Your endpoint>)
  File.open(_file) do |f|
    req = Net::HTTP::Post::Multipart.new url.path, "file" => UploadIO.new(f, "image/jpeg", "filename")
    res = Net::HTTP.start(url.host, url.port) do |http|
      http.request(req)
    end
  end
end