Support ThreadLocalAccessor for reactor based libraries (WebFlux, WebClient)

[adinauer]

Description

Reactor has released a new version: https://github.com/reactor/reactor/releases/tag/2022.0.3

Looks like Spring is already on the version just before that so will likely have this version soon. https://docs.spring.io/spring-boot/docs/current/reference/html/dependency-versions.html

We should try it and see if it improves our WebFlux support, then fix potential problems and document if needed.

Thanks @maciejwalkowiak for telling us about it 🙏

[adinauer]

Version bump has already landed on main and 3.0.x here: spring-projects/spring-boot@486f3b3 . Micrometer dependency has also been bumped to 1.10.4.

2.7.x seems to stay on an older version of reactor. This means we will only add support for ThreadLocalAccessor in our jakarta module(s) which are meant for Spring Boot 3.

[adinauer]

Just opened a bunch of PRs that add support for ThreadLocalAccessor. When this lands Spring Boot may not have released a version yet that includes all dependencies required with the required version.

I used these dependencies for testing:

implementation("io.projectreactor:reactor-core:3.5.3")
implementation("io.projectreactor.netty:reactor-netty:1.1.3")
implementation("io.micrometer:context-propagation:1.0.2")

reactor.core.publisher.Hooks#enableAutomaticContextPropagation() has to be enabled (SentryWebfluxAutoConfiguration should take care of this for you, just be aware it does this. If you don't want this, please let us know).

Here's the PRs:

• Add sample for Spring Boot 3 WebFlux Add sample for Spring Boot 3 / Jakarta WebFlux #2564
• Implement ThreadLocalAccessor for propagating Sentry hub with reactor / WebFlux Implement ThreadLocalAccessor for propagating Sentry hub with reactor / WebFlux #2570
• Use it in the WebFlux sample Use ThreadLocalAccessor in Spring Boot 3 WebFlux sample #2569
• Use it in Spring (non WebFlux) sample where we use WebClient (which also uses reactor) Use ThreadLocalAccessor for WebClient in Spring Boot 3 sample #2568
• Clone hub for request from main hub instead of whatever hub happens to be set on the current thread to avoid leaking Clone hub from main hub for every WebFlux request #2567
• Use the request hub also when handling exceptions for WebFlux Use the same hub in WebFlux exception handler as we do in WebFilter #2566

We still need some internal discussions around some of these changes. Stay tuned

[adinauer]

Spring Boot 3.0.3 is out now providing the needed version of reactor.