Support logging for Puma

[tmaier]

Puma supports custom loggers. See puma/puma#2770

By default, puma logs only to stdout.
Using the custom logger it should be possible to log to AppSignal Logging.

[tombruijn]

Thanks for the suggestion!
Not sure if it will fit in with our logging recommendations, but we'll have a look at what logs Puma sends.

[tmaier]

Well... the question is what to log. I had the issue, that on DigitalOcean App Platform the puma server did not start.
They also do not have a "H18" error message, like Heroku and I was also unable (to date) to get the logs on platform-level.

This means, I was unable to see that the puma server failed and might have shown a Oout of Memory error message or a "restart event" is happneing.

[tombruijn]

I made some changes in PR #1393 that may make this possible, if I look at Puma's implementation.

Oh no, they want write as a method.

I can get logs in from the app itself, but not Puma. Probably an issue with the extension not having started in the Puma main process. If I start it in the main process, I receive no logs or tracing at all.

Because of the extension issue in the main process I wonder if it's not easier to call our JSON log endpoint?