With rails 5.1.7 I am getting:
Errno::EROFS:
Read-only file system @ dir_s_mkdir - /webdrivers
when trying to execute system test with capybara and the webdrivers gem
The Webdrivers gem needs to be able to download the latest/correct version of driver (chromedriver, geckodriver, etc) to match the browser you're using for testing. You can specify where it downloads those files to using Webdrivers.install_dir
as documented at https://github.com/titusfortner/webdrivers#download-location. You'll need to set that to a writable location.