Support to Spring Webflux (reactive handlers)

[atrujillofalcon]

Logbook already has Spring support to traditional controllers model. In Spring Boot 2.X was introduced the reactive programming model with spring-webflux. Would be nice have Logbook support to this approach

See more details of Webflux here: https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#spring-webflux

Context

I use Logbook for many micro-services in my job. We need to integrate Logbook in some reactive webflux services.

Possible Implementation

By WebHandler API? -> https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#webflux-web-handler-api

Thanks for your attention.
Greetings!

[whiskeysierra]

The traditional, blocking approach is supported via a Servlet Filter, which has the nice benefit of not being tied to Spring directly, i.e. it's useful for other frameworks as well.

Is there a usable, standardized API for nio that Spring is using?

[whiskeysierra]

https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#webflux-httphandler sounds like a good start. But also looks like there is no common API.

[atrujillofalcon]

I see your point. Spring Webflux is built on Project Reactor so we can built the reactive Filter using a common API like CompletableFuture's or RxJava because this libraries are compatible with Project Reactor. Could you give me more details on how the current Logbook integration with Spring works?

[whiskeysierra]

It's basically just a servlet filter, see https://github.com/zalando/logbook/tree/master/logbook-servlet, that we register using Spring's FilterRegistrationBean.

[atrujillofalcon]

Let me think of an approach, and I'll let you know if I can come up with a standard solution.

[atrujillofalcon]

A question, the logbook-core module is not tied to the servlet API? In this case, would it be possible to create a new module called spring-webflux or something similar?

[whiskeysierra]

the logbook-core module is not tied to the servlet API

True.

In this case, would it be possible to create a new module called spring-webflux or something similar?

Possible, yes. But I'd prefer a solution that is not tied to spring.

[fragonib]

+1

[gmariotti]

Not sure if this feature is still under consideration, but creating a Netty module would make this library easy to use also for Vert.x and Quarkus.

[whiskeysierra]

Not sure if this feature is still under consideration, but creating a Netty module would make this library easy to use also for Vert.x and Quarkus.

That sounds promising then. Normally I'm opposed to bind myself to an implementation, but in this case it seems that Netty is pretty much the NIO framework of choice and we would cover the following application frameworks:

• Spring WebFlux
• Micronaut
• Vert.x
• Quarkus

[whiskeysierra]

Anyone here who has experience customizing the netty setup (preferably adding custom channel handlers) for Vert.x, Quarkus and/or Micronaut?

[whiskeysierra]

Turns out registering a custom ChannelHandler in using Spring WebFlux + Netty is easy. But for the others that seems to be hard:

• Micronaut: Micronaut configuration #629, Allow custom ChannelHandlers to control their position micronaut-projects/micronaut-core#2719
• Vert.x: https://stackoverflow.com/questions/59987216/how-can-i-add-a-custom-netty-channell-handler-in-vert-x/59989085#59989085
• Quarkus: https://quarkusio.zulipchat.com/#narrow/stream/187030-users/topic/Adding.20a.20custom.20Netty.20ChannelHandler (no answer yet)

[gmariotti]

I think Quarkus is running on top of Vert.x so, it might have the same problem. If Micronaut is planning to support it, I would still go for a Netty module, otherwise doing a Spring WebFlux specific one is easier.

[whiskeysierra]

I already have a working Netty-based solution locally. I wanted to add tests for each framework. Spring works, but I stumpled for the other three.

[gmariotti]

That's great!! Is it something you can share already? I would be interested to see if I can create a similar module for Vert.x

[whiskeysierra]

I pushed my current branch here: https://github.com/zalando/logbook/tree/feature/netty/logbook-netty/src/main/java/org/zalando/logbook/netty

Maybe the existing API for vert.x already allows enough to register it? See http://www.julienviet.com/advanced-vertx-guide/#integrating-netty