Heroku: unable to connect to chromedriver 127.0.0.1:9515 when using Watir/Selenium

Question

This runs locally (without specifying driver_path), but not on Heroku.

Code:

Selenium::WebDriver::Chrome.driver_path = ENV[         


        

Answer 1

This is possible on Heroku.

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Confusing chrome and chromedriver

Your configuration is mixing up chromedriver and Chrome. GOOGLE_CHROME_SHIM points to the Chrome executable google-chrome-stable, not to chromedriver. The line below results in Selenium executing the wrong binary, which results in the misleading error message.

Selenium::WebDriver::Chrome.driver_path = ENV['GOOGLE_CHROME_SHIM'] # WRONG!

As of writing this (Jan '18) the chromedriver build pack automatically adds /app/.chromedriver/bin to the $PATH variable. If you delete the above line Selenium should again be able to find chromedriver automatically.

And then?

You probably added the line above to fix Selenium not being able to find the Chrome binary. The error message for that would have looked something like:

Selenium::WebDriver::Error::UnknownError: unknown error: cannot find Chrome binary

You can fix this by telling Selenium where the Chrome binary is located using Selenium::WebDriver::Chrome::Options. The following code should accomplish that.

options = Selenium::WebDriver::Chrome::Options.new
chrome_bin_path = ENV.fetch('GOOGLE_CHROME_SHIM', nil)
options.binary = chrome_bin_path if chrome_bin_path # only use custom path on heroku
options.add_argument('--headless') # this may be optional
driver = Selenium::WebDriver.for :chrome, options: options
driver.navigate.to "https://stackoverflow.com"

Buildpacks

This should all be possible with the standard chrome and chromedriver build packs:

https://github.com/heroku/heroku-buildpack-google-chrome.git https://github.com/heroku/heroku-buildpack-chromedriver.git

You may need heroku-buildpack-xvfb-google-chrome instead of vanilla chrome if you're automating clicks in the browser, but that should not be required just to get headless chrome running.