fix: add support for exporting opentelemetry logs_level_enabled feature

[HoKim98]

Motivation

When building tracing-opentelemetry and the opentelemetry crate with logs_level_enabled feature on a crate, it fails to build on opentelemetry>=0.25.0.

It's because the opentelemetry::logs::Logger trait contains a fn event_enabled which is only enabled with the logs_level_enabled feature.

See also:
https://github.com/open-telemetry/opentelemetry-rust/blame/3976f3d4867d564c98a566df83eb59e31c653b84/opentelemetry-sdk/src/logs/log_emitter.rs#L270-L284

Solution

Add support for exporting opentelemetry logs_level_enabled feature

[djc]

So is the motivation here that in your downstream crate you don't depend on opentelemetry-sdk directly at all?

[HoKim98]

Ah no, I used both opentelemetry and opentelemetry_sdk crates with logs_level_enabled feature.

[djc]

So why should this crate be involved in that decision?