heroku-buildpack-xvfb-google-chrome

by kevinsawicki

GitHub Readme.md

heroku-buildpack-xvfb-google-chrome

This buildpack downloads and installs Xvfb and Google Chrome from your choice of release channels.

Note that Google Chrome now has a --headless flag, so for many applications, Xvfb may not be required. If so, consider this buildpack instead.

Only supported on Cedar-14

Note that this buildpack only works on Cedar-14 stack. For the Heroku-16 stack only the Headless Chrome buildpack is supported. For more details see Known Issues for Heroku CI.

Channels

You can choose your Chrome release channel by specifying GOOGLE_CHROME_CHANNEL as a config var for your app, in your app.json (for Heroku CI and Review Apps), or in your pipeline settings (for Heroku CI).

Valid values are stable, beta, and unstable. If unspecified, the stable channel will be used.

Shims and Command Line Flags

This buildpack installs shims that always add --disable-gpu and --no-sandbox to any google-chrome command as you'll have trouble running Chrome on a Heroku dyno otherwise.

You'll have two of these shims on your path: google-chrome and google-chrome-$GOOGLE_CHROME_CHANNEL. They both point to the binary of the selected channel.

Selenium

To use Selenium with this buildpack, you'll also need Chrome's webdriver. This buildpack does not install chromedriver, but there is a chromedriver buildpack also available.

Additionally, chromedriver expects Chrome to be installed at /usr/bin/google-chrome, but that's a read-only filesystem in a Heroku slug. You'll need to tell Selenium/chromedriver that the chrome binary is at /app/.apt/usr/bin/google-chrome instead.

To make that easier, this buildpack makes $GOOGLE_CHROME_BIN, and $GOOGLE_CHROME_SHIM available as environment variables. With them, you can use the standard location locally and the custom location on Heroku. An example configuration for Ruby's Capybara:

chrome_bin = ENV.fetch('GOOGLE_CHROME_SHIM', nil)

chrome_opts = chrome_bin ? { "chromeOptions" => { "binary" => chrome_bin } } : {}

Capybara.register_driver :chrome do |app|
  Capybara::Selenium::Driver.new(
     app,
     browser: :chrome,
     desired_capabilities: Selenium::WebDriver::Remote::Capabilities.chrome(chrome_opts)
  )
end