Ruby – How to use Selenium Webdriver on headless Chrome

I'm learning to use Selenium for basic things like taking a screenshot, scraping, and testing and would like to use it with headless Chrome, which is now stable as of Chrome 59.

I have been able to take a screenshot using the 'selenium-webdriver' gem and chromedriver, but not headless.

Here is the ruby script that I am running which hangs after starting to initialize the driver

require 'rubygems'
require 'selenium-webdriver'

Selenium::WebDriver.logger.level = :debug
p 'initializing driver'
driver = Selenium::WebDriver.for :chrome, switches: %w[--headless --disable-gpu --screenshot --hide-scrollbars]
p 'navigating to Google'
driver.navigate.to "http://google.com"  
driver.save_screenshot("./screen.png")
driver.quit

and the output from the logs:

:> ruby rubytest.rb
"initializing driver"
2017-06-07 15:55:43 DEBUG Selenium Executing Process 

["/Users/name/Documents/scrapings/python/env/bin/chromedriver", "--port=9515"]
2017-06-07 15:55:43 DEBUG Selenium polling for socket on ["127.0.0.1", 9515]
Starting ChromeDriver 2.29.461585 (0be2cd95f834e9ee7c46bcc7cf405b483f5ae83b) on port 9515
Only local connections are allowed.
2017-06-07 15:55:43 INFO Selenium -> POST session
2017-06-07 15:55:43 INFO Selenium    >>> http://127.0.0.1:9515/session | {"desiredCapabilities":{"browserName":"chrome","version":"","platform":"ANY","javascriptEnabled":true,"cssSelectorsEnabled":true,"takesScreenshot":false,"nativeEvents":false,"rotatable":false,"chromeOptions":{"args":["--headless","--disable-gpu","--screenshot","--hide-scrollbars"]}}}
2017-06-07 15:55:43 DEBUG Selenium      > {"Accept"=>"application/json", "Content-Type"=>"application/json; charset=utf-8", "Content-Length"=>"284"}
[RUBY BACKTRACE TO DRIVER INITIALIZATION]

I have tried using the JavaScript and Python drivers with similar code and nothing works. When I try this with Python, the error message is

WebDriverException: Message: unknown error: Chrome failed to start: exited abnormally
  (Driver info: chromedriver=2.29.461585 (0be2cd95f834e9ee7c46bcc7cf405b483f5ae83b),platform=Mac OS X 10.12.5 x86_64)