Support Micronaut 4 Context Propagation

[jjathman]

Feature description

With Micronaut 4, how context propagation works (specifically something like SFL4J's MDC) was reworked using a new API documented here. It doesn't appear as though the GCP libraries are supporting this.

For example, when using the reactive PubSub client, any logging done within a map/doOnSuccess/doOnError call does not have the MDC from the calling thread even when the context propagation is setup.

Would it be possible to support this? I'm not sure what needs to change to enable this feature.

[SushmaReddyLoka]

@jeremyg484 , @graemerocher can you help on this.
We upgraded to micronaut 4.6.6 and are seeing similar issue with project reactor calls, we have logs in doOnSuccess and context is missing in them. Also after switching back from reactor thread to default-nioEventLoopGroup-xx, the context which was originally set on default-nioEventLoopGroup-xx is also lost.

First we upgraded to 4.6.6 and observed that MDC.getCopyOfContextMap() was returning null altogether so we went ahead and added implementation("io.micrometer:context-propagation"), now we don't see NPE as MDC is having PropagationContext in it, but the rest of context is still lost.

We have been extending reactor.core.CoreSubscriber, and copying the currentContext() to MDC so far for context propogation.

Created Q/A for the same at micronaut-projects/micronaut-core#11346

[graemerocher]

maybe provide a reproducer please