Emit log message for incompatible Lograge setup

[marcotc]

Closes #2012

This PR emits an error-level log message when the lograge gem is used with Rails tagged logging, which is configured by default in Rails since Rails 5.

We can't practically fix the issue here in dd-trace-rb, since the issue is a log formatting conflict between lograge and Rails.
The reason this affects APM Tracing is because it breaks trace-log correlation.

The only alternatives are to either: disable Rails tagged logging; or not use lograge.

The investigation and suggest alternatives are well documented here: #2012 (comment)

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-08-12 23:14:11

Comparing candidate commit 482b48a in PR branch lograge-rails with baseline commit 6b50227 in branch master.

Found 2 performance improvements and 0 performance regressions! Performance is the same for 21 metrics, 2 unstable metrics.

scenario:profiler - Allocations ()

• 🟩 throughput [+165850.392op/s; +173043.914op/s] or [+4.230%; +4.414%]

scenario:profiler - sample timeline=false

• 🟩 throughput [+0.257op/s; +0.396op/s] or [+3.886%; +5.980%]

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.84%. Comparing base (6b50227) to head (482b48a).
Report is 8 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3839      +/-   ##
==========================================
- Coverage   97.84%   97.84%   -0.01%     
==========================================
  Files        1264     1264              
  Lines       75682    75696      +14     
  Branches     3720     3723       +3     
==========================================
+ Hits        74053    74061       +8     
- Misses       1629     1635       +6     

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[armstrjare]

We've started getting this error message since this update.

However, we already account for this with customisations to the log formatter to output in JSON and include Datadog tags:
Part of our implementation for this is made public here: https://github.com/armstrjare/rails-json-tagged-logging

Can we add a way to disable this warning to stop polluting our startup logs?

@marcotc @TonyCTHsu

[alexevanczuk]

Hey @marcotc just wanted to +1 for a way to disable this warning message.

I'm also confused about the exact behavior that's broken. We set up some log remapping that ensures the datadog trace IDs are properly read as trace IDs and we still have log correlation working. Is there anything else that might be missing with lograge that I'm not seeing?

Thank you!