Micronaut 5 Release Themes

[graemerocher]

The discussion here is for the release of Micronaut 5.

Currently it is a priority to avoid breaking changes to the framework and ensure an easy upgrade. That said certain third party dependencies have moved on to new major versions that may include upgrade requirements.

APIs deprecated in the 4.x line will be removed.

Micronaut 5 will upgrade third parties and define a new baseline Java version.

Third Party Dependency Upgrades

• GraalVM 25 minimum
• JDK 21 minimum
• Kotlin 2 minimum
• Groovy 5 minimum
• Kafka 4
• Hibernate 7
• MongoDB Java Driver 5.5
• Maven 4
• Gradle 9
• Logback 1.5.x

Enhancements

• JSpecify by Default instead of core Nullable annotation (but retain latter to avoid breaking changes)
• Support for Gradle/Maven plugins to check for null
• Support for Scoped Values for Transaction / Context Propagation

Deprecated and Removed Core Features

The following features will be removed from core:

• KAPT support

Breaking Changes Under Consideration

Breaking changes in either the API or behaviour will be kept to a minimum. The following rules will be followed:

• For behaviour changes these will be clearly documented with automated OpenRewrite based upgrade required. Old behaviour should be restorable via configuration if possible.
• No API change is allowed that doesn't already exist in 4.x and is marked as @Deprecated(forRemoval)

The following modules are being considered for deprecation:

• Micronaut Microstream

[dstepanov]

My suggestions:

• Require @ReflectiveAccess for bean context cases when reflection is required in Micronaut 5 #7973
• Consider extracting HTTP modules from Core #7970
• Extract internal writers , builders from core-processor to a new dependency #12012

Regarding Kotlin and KAPT, we will simply remove all the tests that are not Kotlin 2 KSP 2

[sascha-frinken]

Removing KAPT means no PicoCLI?!

[dstepanov]

We are not going to remove anything, we just not going to support it. Kotlin’s support for KAPT is very limited anyway

[graemerocher]

it is not really our choice anyway. Jetbrain's have deprecated support for KAPT

[arndey]

Are there plans to promote the "experimental mode to run virtual threads on the Netty event loop" feature to stable?

[arndey]

@dstepanov

[dstepanov]

It is a hack at this moment because there is no public API to do so, correct me if I’m wrong @yawkat

[arndey]

I've noticed experimental work in Micronaut's codebase for supporting Kotlin suspend functions in AOP tools, but I couldn't get it to work.

In our project, we abandoned coroutines due to the lack of proper support for suspend functions in Micronaut's AOP tools, despite appreciating Kotlin's coroutines and async capabilities. We switched to virtual threads, which mainly avoid the need for suspend but lack other benefits of coroutines. Is there community interest in improving support for Kotlin suspend functions in Micronaut's AOP tools?

Thanks

[arndey]

What are you calling AOP tools?

Method Interceptors for example

[dstepanov]

Interceptors do support coroutines. Thoses are intercepted as Completable futures

[arndey]

A class implementing MethodInterceptor cannot declare intercept as a suspend function, as far as I remember there was smth like KotlinMethodInterceptor, but it was either experimental or there was other reason why it doesn't solve the problem

[dstepanov]

You need to do something like this:

         InterceptedMethod interceptedMethod = InterceptedMethod.of(context, conversionService)
                return switch (interceptedMethod.resultType()) {
                    case PUBLISHER ->
                            handlePublisher(...
                    case COMPLETION_STAGE ->
                            handleCompletionStage(...
                    case SYNCHRONOUS ->
                            handleSynchronous(...
                };
          ```

[dstepanov]

Suspend is handled by COMPLETION_STAGE

[sdelamo]

we have project board with other issues where we should organise work:

5.0.0 Release (view)

[altro3]

Please, divide core repo to micronaut-core and micronaut-http. Core repo now is so fat!

[altro3]

Also, don't forget these PRs:

#10130
#10613

[altro3]

Also, it's time to fix childhood illness: #10512