Background worker doesn't work for classic Sinatra apps

[st0012]

Issue Description

When being ran in classic mode and without config.ru (e.g. bundle exec ruby app.rb), Sinatra apps will be initialized at the end of the Ruby script by a at_exit callback. And that means that the SDK's at_exit callback will also be called:

sentry-ruby/sentry-ruby/lib/sentry-ruby.rb

Lines 216 to 219 in 0f66522

	at_exit do
	@session_flusher&.kill
	@background_worker.shutdown
	end

So when app.rb is loaded, the SDK's background worker is also disabled 🙈 Therefore, no event will be sent by the SDK.

Reproduction Steps

Script

# app.rb
require 'sinatra'
require 'sentry-ruby'

Sentry.init do |config|
  config.dsn = 'DSN'
end

use Sentry::Rack::CaptureExceptions

get "/" do
  raise "foo"
end

Command

$ bundle exec ruby app.rb

Expected Behavior

Errors will be reported.

Actual Behavior

Errors are not reported because the background worker is shut down unexpectedly.

Ruby Version

3.1.0

SDK Version

5.2.1 & master

Integration and Its Version

No response

Sentry Config

No response

[st0012]

@sl0thentr0py This is a funny behavior that really puzzled me for a while 😂

[sl0thentr0py]

We already had a support ticket for this, the following workaround works

# app.rb
require 'sentry-ruby'

Sentry.init do |config|
  config.dsn = 'DSN'
end

require 'sinatra'
use Sentry::Rack::CaptureExceptions

get "/" do
  raise "foo"
end

Not ideal but it's just because of this funny business that sinatra does with at_exit.

[st0012]

Oh damn. How many support tickets do we have that could've been turned into issues 😂
I don't know how to fix this either. But I'm going to add logging (debug) when the background worker is shutdown. That'll make similar issues easier to investigate.

[sl0thentr0py]

How many support tickets do we have that could've been turned into issues

Oh not too many so far, but yeah that's a good point that I could definitely document some of those in the open on github. Just need to be less lazy. Will keep in mind. :)

[st0012]

Haha, I'm not blaming you! It's a fun issue to debug and a good way to learn Sinatra anyway. I just didn't expect that you are already aware of it.

[github-actions]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you label it Status: Backlog or Status: In Progress, I will leave it alone ... forever!

---

"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀

[sl0thentr0py]

this is now documented https://docs.sentry.io/platforms/ruby/guides/rack/#without-rackup
so I'm closing this