[Tracking Issue] Improve Bun Support #19707
Description
The Bun runtime is getting used more and more and the JavaScript SDKs should support this ongoing trend. This issue is a tracking issue that shows current missing features with the Bun runtime.
Missing auto-instrumentation (because module.register is not supported in Bun)
In general, a lot of missing auto-instrumentation is based on the missing support for module.register in Bun (Bun docs). Auto-instrumentation of ES Modules in OpenTelemetry is based on import-in-the-middle which calls module.register.
A real fix would require either (a) Bun improving module.register() + ESM namespace mutability support, or (b) the SDK implementing a Bun-specific loader (e.g., using Bun's native plugin API) to intercept imports before they are bound.
Missing HTTP spans
The HTTP spans are created based on what diagnostic channels publish. Bun supports diagnostics channels but does not yet publish the necessary notifications. There is an open PR for that in Bun: oven-sh/bun#24375