GitHub is rolling out ubuntu-24.04 as their new ubuntu-latest, and I just discovered that this image is missing readline.h. As a result, readline-ext cannot be installed without first installing the development packages, and several of my builds failed.

• Ubuntu-latest workflows will use Ubuntu-24.04 image actions/runner-images#10636
• nevans/test-setup-ruby-readline — a minimal test repo
  • Gemfile
  • GitHub Actions workflow
  • Workflow results — Here you can see that bundle install only fails for ubuntu-24.04.

Since readline-ext was removed from ruby 3.3, maybe this isn't something that needs to be addressed here. But it took me a few minutes to debug and I couldn't find any documentation of this issue, neither in this repo nor in actions/runner-images. So, rather than create an issue, I'm simply posting about it here, in case it might help someone else.

I assume that this can be fixed by simply adding a sudo apt-get install libreadline-dev step, before the ruby/setup-ruby setup. That said, I no longer need this dependency in the project that triggered this issue, so I'm simply removing it from our Gemfile. 😉