v1.21.0 causes outages due to a nil error in rack middleware

[ejoubaud]

Current behaviour

Nil error in ddtrace rack middleware when requesting any page on a Rails 7.1.3.2 app.

Steps to reproduce

• upgrade to 1.21.0
• start rails app (rails server)
• try to load any page
• get the following error:

Puma caught this error: undefined method `+' for nil:NilClass (NoMethodError)
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/ddtrace-1.21.0/lib/datadog/tracing/contrib/rack/middlewares.rb:134:in `call'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/rack-cors-2.0.2/lib/rack/cors.rb:102:in `call'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/webpacker-6.0.0.rc.6/lib/webpacker/dev_server_proxy.rb:25:in `perform_request'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/rack-proxy-0.7.6/lib/rack/proxy.rb:87:in `call'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/railties-7.1.3.2/lib/rails/engine.rb:536:in `call'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/configuration.rb:272:in `call'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/request.rb:100:in `block in handle_request'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/thread_pool.rb:378:in `with_force_shutdown'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/request.rb:99:in `handle_request'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/server.rb:464:in `process_client'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/server.rb:245:in `block in run'
/Users/ejoubaud/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/puma-6.4.2/lib/puma/thread_pool.rb:155:in `block in spawn_thread'

Looks like it was introduced here

Note also the commented out # binding.pry in that commit

Environment

• ddtrace version: 1.21.0
• Configuration block (Datadog.configure ...): happens even when block is entirely removed
• Ruby version: 3.2.2
• Operating system: Mac, Linux
• Relevant library versions:

[ivoanjo]

Hey! Sorry that you ran into this 😰. We're going to publish 1.21.1 ASAP with a revert of this change, since it clearly was not ready (#3539).

Thanks for the patience.

[ivoanjo]

(We've merged a fix for this, and we're in the final validation steps before publishing a 1.21.1 release with the fix. Because a lot of folks seem to be bitten by this, I'll go ahead and reopen the issue until we actually put the release out so folks can easily find this ticket)

[TonyCTHsu]

👋 @ejoubaud 1.21.1 has been released!