http-promise.rb

        ctx = OpenSSL::SSL::SSLContext.new
        ctx.set_params(verify_mode: OpenSSL::SSL::VERIFY_PEER)

        raw_sock = TCPSocket.new(host, 443)

        ssl_sock = OpenSSL::SSL::SSLSocket.new(raw_sock, ctx)
        ssl_sock.hostname = host
        ssl_sock.sync_close = true
        ssl_sock.connect

        req = Net::HTTP::Head.new(url)
        req['Host'] = host
        req['Authorization'] = "Bearer #{token}"
        req['Connection'] = 'close'
        req.exec(ssl_sock, '1.0', req.path)

proc do
        resp = Net::HTTPResponse.read_new(Net::BufferedIO.new(ssl_sock))
        ssl_sock.close
        if resp.code.to_i != 302
          raise(OperationFailed, "wanted #{code}, got #{resp.code}") unless resp.code.to_i == code
        end
        URI.parse(resp['Location'])
end