How can I retrieve the user agent in a headless browser environment?

Other Questions Headless Browser
1

I am conducting tests using a headless Chrome browser and need to obtain its user agent string. For a standard Chrome instance, I utilize the following snippet to retrieve the user agent:

page.run_script("navigator.userAgent"); // this works as intended

However, this approach does not function as expected in headless mode. Is there a method to successfully fetch the user agent in this scenario?

Note: My testing framework includes Ruby and Capybara.

2

Try setting the user agent explicitly in your Capybara setup. This usually circumvents the issue in headless mode.

Capybara.register_driver :headless_chrome do |app|
  Capybara::Selenium::Driver.new(app,
    browser: :chrome,
    options: Selenium::WebDriver::Chrome::Options.new(args: ['headless', 'user-agent=custom_user_agent']))
end

Replace 'custom_user_agent' with the desired string. This forces the browser to use it.

3

To retrieve the user agent in a headless Chrome environment when using Ruby with Capybara, you might need to adjust your approach slightly, as headless browsers can have quirks. Instead of relying solely on executing a JavaScript snippet, you can utilize Capybara and Selenium's capabilities to interact directly with the browser configuration. Here's an alternative way:

Capybara.register_driver :headless_chrome do |app|
  options = Selenium::WebDriver::Chrome::Options.new(
    args: ['headless', 'disable-gpu']  # Including 'disable-gpu' for extra headless stability
  )
  Capybara::Selenium::Driver.new(app,
    browser: :chrome,
    options: options
  )
end

session = Capybara::Session.new(:headless_chrome)

# Navigate to a simple page
session.visit('http://example.com')

# Retrieve user agent
user_agent = session.evaluate_script('navigator.userAgent')
puts user_agent

This approach sets up a headless Chrome session and uses Capybara's evaluate_script method to execute JavaScript for fetching the user agent. By initially visiting a simple page, you ensure that the browser context is correctly set up before executing the script. This should give you the accurate user agent string even in a headless environment.