Using Chessputzer's online instance as an API to generate a FEN from an image of a chessboard

chessputzer_client.rb

require 'faraday'

conn = Faraday.new('https://www.ocf.berkeley.edu') do |f|
  f.request :multipart
  f.request :url_encoded
  f.adapter :net_http # This is what ended up making it work
end

res = diagram.open do |file|
  payload = { :file => Faraday::UploadIO.new(file, 'image/png') }
  conn.post('/~abhishek/putz/run.fcgi/upload', payload)
end

html_res = Nokogiri::HTML(res.body)
fen = html_res.css("p.boxed").first.text.split("\n").first.split(":").second.strip