puma plugin :tailwindcss dies silently after some time when using docker.

[stillhart]

I apologize for the vague issue description.

I'm using the Puma plugin with plugin :tailwindcss in my puma.rb file, as outlined in the README.md. It works perfectly and boots up without any issues. However, after some hours or days, the Tailwind CSS plugin silently stops working—it either dies or no longer detects changes. At that point, I have to restart the Puma process. There are no logs indicating that it has crashed or stopped, and I can’t find any trace of what’s happening.

This issue occurs across multiple setups: Rails 7.2, Rails 8.0, Puma 6.5, tailwindcss-rails 3.4, Ruby 3.3, and Ruby 3.4. Interestingly, I haven’t noticed this behavior when running natively on macOS, but it happens frequently across various projects when using Docker. I’m using the official Ruby Docker Debian image (https://hub.docker.com/_/ruby/). In some projects, I’ve even followed the official Rails Dockerfile example.

I suspect it might be related to running out of file watchers, but Rails itself continues to detect code changes without any problems—it’s only Tailwind CSS that stops compiling.

I’m perfectly fine if this issue gets closed due to lack of reproducibility. My goal is simply to see if anyone else has encountered the same problem and can provide additional insights or data points. That’s all I’m hoping for.

For now, the workaround is straightforward: just restart the process. This is only in development, not production, so it’s not a critical issue.

[flavorjones]

Hi. Sorry you're having a problem.

Can you share what version of tailwindcss-ruby you're using? It would be good to know if this is an issue with the v3 CLI or the v4 CLI (or both).

[stillhart]

No sorry :-). I'm not even sure if it's really only my problem.

My Gemfile.lock shows the following:

    tailwindcss-rails (3.3.1)
      railties (>= 7.0.0)
      tailwindcss-ruby (~> 3.0)
    tailwindcss-ruby (3.4.17)
    tailwindcss-ruby (3.4.17-aarch64-linux)
    tailwindcss-ruby (3.4.17-arm-linux)
    tailwindcss-ruby (3.4.17-arm64-darwin)
    tailwindcss-ruby (3.4.17-x86_64-darwin)
    tailwindcss-ruby (3.4.17-x86_64-linux)

I noticed that it doesn't stop but it seems like it gets stuck while compiling. In this case I trigger a compile by saving a random file. Every 8th time it hangs.

docker compose exec web bundle exec rails tailwindcss:watch

Rebuilding...

Done in 1771ms.

Rebuilding...

Done in 331ms.

Rebuilding...

Done in 220ms.

Rebuilding...

Done in 189ms.

Rebuilding...

Done in 179ms.

Rebuilding...

Done in 143ms.

Rebuilding...

Done in 183ms.

Rebuilding...

# never recovers from here

I think I may even mix the issue. As said, in other project, I'm fine the whole day, go sleep, come back and tailwindcss is not compiling anymore.

Triggering a build every second never makes it get stuck. It just works.

watch -n1 docker compose exec web bundle exec rails tailwindcss:build

[flavorjones]

Well, it's interesting that you're using tailwindcss-ruby v3, because that's shipping the very stable tailwindcss CLI from v3.

Have you tried the suggestions from the README's troubleshooting guide related to docker containers: https://github.com/rails/tailwindcss-rails?tab=readme-ov-file#running-in-a-docker-container-exits-prematurely