feat: Ruby Logger instrumentation

[kaylareopelle]

Description

This an OpenTelemetry logs bridge for Ruby's standard Logger library.

It also includes patches to ActiveSupport::Logger.broadcast and the ActiveSupport::BroadcastLogger to emit only one log record for a broadcast.

@khushijain21 is a co-author of this PR and contributed functionality as part of her LFX mentorship with OpenTelemetry in 2024.

Closes #668

[kaylareopelle]

New Relic uses formatted_message here. This includes both the progname and the message in the body, whereas msg does not include the progname. Which seems more appropriate?

[kaylareopelle]

I'm still trying to figure out why one of the tests is failing on the CI, but passes locally. However, everything except the ActiveSupportLogger code should be ready for review. Please take a look and I'll push the update as soon as I can!

[tomash]

I am very interested in getting this to work with Opentelemetry. Any way I could help with this work?

[kaylareopelle]

Hi @tomash! Thanks for reaching out. It's great to hear there's interest in this PR. I'd love your help!

The features for the bridge should be complete. I just updated the branch to align with some of the changes in main. Before this is merged, we need to agree on the approach and get more feedback overall.

Specifically, I could use help with:

1. Reviewing the code: What are your thoughts on how OpenTelemetry logs are bridged from the Ruby Logger? Do you have suggestions on how we could improve the approach? An alternative approach has been presented in Rails <> OpenTelemetry Logs opentelemetry-ruby#1789, would you rather see something like this?

2. Testing the code in an app: Install the gem from this branch and provide feedback on how it works in your application. This is a Gemfile from a sample application I wrote to add the OpenTelemetry bridge for the Ruby logger to a Rails application. Give it a try and let us know how it goes.

[tomash]

@kaylareopelle

For now I have this monstrosity in Gemfile:

gem "opentelemetry-instrumentation-logger",
  git: "https://github.com/kaylareopelle/opentelemetry-ruby-contrib.git",
  branch: "logger-instrumentation",
  glob: "instrumentation/logger/opentelemetry-instrumentation-logger.gemspec"

And I can confirm it works well for our app (the logs appear in Honeycomb just as events). The only problem is that Rails logs are noisy by default and it makes "top messages" unusable (top message being "rendered profiles/_carousel.html.erb"), so I've also dropped in Lograge to produce fewer logs.

I haven't seen open-telemetry/opentelemetry-ruby#1789 , will evaluate and compare! I do like how lightweight and easy to read it is.