Why does my 'headless' browser script open Firefox and fail in cron jobs?

Other Questions Headless Browser
1

I’m having trouble with a script that’s supposed to run headless in a cron job. It uses the Headless gem with Watir-WebDriver but still opens Firefox when I run it. This causes issues in the cron job environment.

Here’s a simplified version of my code:

require 'watir-webdriver'
require 'headless'

headless = Headless.new
browser = Watir::Browser.start 'http://example.com'
browser.text_field(id: 'username').set 'myuser'
browser.text_field(id: 'password').set 'mypass'
browser.button(id: 'login').click

# Do some stuff

browser.close
headless.destroy

The script works fine when run manually but fails in the cron job. I thought Headless was meant to run without accessing the display, like PhantomJS.

I tried PhantomJS too but it timed out on the login page. Any ideas on how to make this work in a cron job? Thanks!

2

hey mate, i’ve had this prob too. try adding headless.start before creating the browser. like this:

headless = Headless.new
headless.start
browser = Watir::Browser.new :firefox

this worked 4 me in cron jobs. good luck!

3

I’ve dealt with this issue before in production environments. One often overlooked aspect is the user context under which the cron job runs. Ensure your cron job is executing under a user with the correct permissions and environment variables set.

Consider using Firefox’s built-in headless mode instead of the Headless gem:

options = Selenium::WebDriver::Firefox::Options.new(args: ['-headless'])
browser = Watir::Browser.new(:firefox, options: options)

This approach has been more reliable in my experience, especially when dealing with cron jobs on different server setups. Also, don’t forget to set the PATH environment variable in your cron job to include the directory where Firefox and geckodriver are installed.

Lastly, if you’re still having issues, try running your script with xvfb-run command. This creates a virtual framebuffer, which can solve display-related problems in headless environments.

4

I’ve encountered similar issues with headless browser scripts in cron jobs. From my experience, the problem might be related to the environment variables in the cron job context. Cron jobs often run with a limited set of environment variables, which can cause issues with X11 display settings.

Here’s what worked for me:

  1. Explicitly set the DISPLAY variable in your script:

    ENV['DISPLAY'] = ':99'

  2. Make sure Xvfb is installed and running on that display:

    Xvfb :99 -ac &

  3. Consider using the ‘whenever’ gem to manage your cron jobs in Ruby. It provides a cleaner syntax and helps with environment setup.

Also, ensure your cron job has the necessary permissions to access the X server. If all else fails, you might want to look into using Selenium with Chrome in headless mode, which I’ve found to be more reliable in cron environments.

Remember to log errors and output to a file for easier debugging when running in cron. Good luck!