Attach Watir (and Selenium) to an already running browser (Chrome)

script.rb

# I had to automate a few tasks in my browser with my current logged session, but by default 
# Selenium always starts a new session.
# After some research, the only way I found to attach Selenium to my running browser session 
# was through the debugger address option.
# Start chrome with the command line option: google-chrome --remote-debugging-port=8181
# Then start selenium webdriver with the debug address option (I could only find the option
# in latest selenium-webdriver gem (v4.0))

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'watir'
  gem 'rexml'
  # So far, only selenium-webdriver 4.0 has support for debugger_address option
  gem 'selenium-webdriver', '~> 4.0.0.rc1'
end

require 'watir'
require 'rexml'

options = Selenium::WebDriver::Chrome::Options.new(debugger_address: '127.0.0.1:8181')
driver = Selenium::WebDriver.for(:chrome, options: options)
browser = Watir::Browser.new(driver)

# do whatever you need: browser.goto('https://foo.bar'); browser.div(id: 'id123')