Support bridging logs to OpenTelemetry API

[ThomasVitale]

Spring Boot offers nice abstractions to configure logs via a unified model. Furthermore, it offers great integrations and customisations for Logback and Log4J2.

The recent addition of structured logging brought many benefits. I wonder if the work that was done for that feature could lay the foundation for implementing a new feature supporting bridging the logs produced by SLF4J/Logback/Log4J2 via the OpenTelemetry API, considering that Spring Boot 4 comes with auto-configuration for OpenTelemetry Logging API and OpenTelemetry Logger Exporter API for OTLP (but no logs are actually exported).

Related/previous work:

• OpenTelemetry Java Instrumentation for Logback Appender
• OpenTelemetry Java Instrumentation for Log4J2 Appender

As always, I'm happy to help any way I can, if this is something interesting for the project.

[jonatan-ivanov]

If you add one of the OTel appenders as a dependency and configure it in your logback/log4j xml does it work? If I remember correctly, this should be the intended setup and Boot does not provide more auto-configuration since those appenders are still in -alpha.