Changing the Guardfile leads to "Address already in use"

1

I found that changing/touching the Guardfile breaks the guard run.

First run of “hanami server” → all works as expected.

Touching/changing the Guardfile leads to:

16:24:38 - WARN - Guardfile changed – _guard-core will exit.
16:24:38 - INFO - Using Guardfile at /home/…/hanami/Guardfile.
16:24:38 - INFO - Puma starting on port 2300 in development environment.
[45593] Puma starting in cluster mode…
[45593] * Puma version: 6.1.1 (ruby 3.2.0-p0) (“The Way Up”)
[45593] * Min threads: 5
[45593] * Max threads: 5
[45593] * Environment: development
[45593] * Master PID: 45593
[45593] * Workers: 2
[45593] * Restarts: (:heavy_check_mark:) hot (:heavy_multiplication_x:) phased
[45593] * Preloading application
/home/…/hanami/vendor/bundle/ruby/3.2.0/gems/puma-6.1.1/lib/puma/binder.rb:335:in `initialize’: Address already in use - bind(2) for “0.0.0.0” port 2300 (Errno::EADDRINUSE)
[…]
16:24:39 - INFO - Guard is now watching at ‘/home/…/hanami’

I then have to stop (Ctrl-C) the server process and restart it.

Pretty sure this is not a Hanami bug but somewhere in Puma or Guard. I could not find anything in Puma or Guard issues that explains it. But it affects new Hanami projects as well. Does anyone have an idea what causes this?

2

@Signum Help me to understand. Do you do the following?

  1. Run hanami server
  2. While the server is running, you modify the Guardfile.
  3. You get the Errno::EADDRINUSE error

If that is the case, between steps 1 and 2, you should stop the server, modify the Guardfile, then start the server again.

This is how Guard works.

3

Yes, that’s what I’m doing. If that’s by design and Guard doesn’t like it then I’ll stop/start it while I’m doing changes. I just wondered because Guard is restarting automatically whenever the Guardfile changes. So it felt like something that is supposed to work.

Thanks for the explanation.

4

:bulb: You can also use Rerun + Overmind which makes for nice workflow without having to worry about restarting the server each time you make a change. Usage is documented in this Hanami demonstration project and here’s the code from the Procfile of that same project if you need it.

5

IMO, this honestly sounds like a bug worth reporting to guard-puma. I’d definitely encourage you to find a minimal reproduction (i.e. single rackup file only, no Hanami) and share it there.