class Aws::Signers::V2

def sign(http_request)
  params = http_request.body.param_list
  params.set('AWSAccessKeyId', @credentials.access_key_id)
  params.set('SecurityToken', @credentials.session_token) if
    @credentials.session_token
  params.set('Timestamp', Time.now.utc.strftime('%Y-%m-%dT%H:%M:%SZ'))
  params.set('SignatureVersion', '2')
  params.set('SignatureMethod', 'HmacSHA256')
  params.delete('Signature')
  params.set('Signature', signature(http_request, params))
  http_request.body = params.to_io
end