Micronaut 2.0.0 doesn't work with metrics

[ilopmar]

Micronaut 2.0 doesn't work with Metrics.

Steps to Reproduce

• git clone https://github.com/micronaut-graal-tests/micronaut-management-graal
• cd micronaut-management-graal
• ./gradlew run

Expected Behaviour

The application should start.

Actual Behaviour

> Task :run FAILED
09:12:58.946 [main] DEBUG i.m.c.beans.DefaultBeanIntrospector - Found BeanIntrospection for type: class io.micronaut.health.HeartbeatDiscoveryClientCondition
09:12:59.005 [main] DEBUG i.m.c.beans.DefaultBeanIntrospector - Found BeanIntrospection for type: class io.micronaut.health.HeartbeatDiscoveryClientCondition
09:12:59.006 [ForkJoinPool.commonPool-worker-2] DEBUG io.micronaut.core.reflect.ClassUtils - Attempting to dynamically load class io.methvin.watchservice.MacOSXListeningWatchService
09:12:59.008 [ForkJoinPool.commonPool-worker-2] DEBUG io.micronaut.core.reflect.ClassUtils - Class io.methvin.watchservice.MacOSXListeningWatchService is not present
09:12:59.009 [ForkJoinPool.commonPool-worker-2] DEBUG io.micronaut.core.reflect.ClassUtils - Attempting to dynamically load class io.methvin.watchservice.MacOSXListeningWatchService
09:12:59.009 [ForkJoinPool.commonPool-worker-2] DEBUG io.micronaut.core.reflect.ClassUtils - Class io.methvin.watchservice.MacOSXListeningWatchService is not present
09:12:59.082 [Thread-1] DEBUG i.m.c.beans.DefaultBeanIntrospector - Found BeanIntrospection for type: class io.micronaut.scheduling.io.watch.FileWatchCondition
09:12:59.235 [main] ERROR io.micronaut.runtime.Micronaut - Error starting Micronaut server: io.micronaut.configuration.metrics.binder.executor.ExecutorServiceMetricsBinder$1 cannot be cast to io.netty.channel.EventLoopGroup
java.lang.ClassCastException: io.micronaut.configuration.metrics.binder.executor.ExecutorServiceMetricsBinder$1 cannot be cast to io.netty.channel.EventLoopGroup
	at io.micronaut.http.server.netty.NettyHttpServer.createWorkerEventLoopGroup(NettyHttpServer.java:480)
	at io.micronaut.http.server.netty.NettyHttpServer.start(NettyHttpServer.java:271)
	at io.micronaut.http.server.netty.NettyHttpServer.start(NettyHttpServer.java:96)
	at io.micronaut.runtime.Micronaut.lambda$start$2(Micronaut.java:70)
	at java.util.Optional.ifPresent(Optional.java:159)
	at io.micronaut.runtime.Micronaut.start(Micronaut.java:68)
	at io.micronaut.runtime.Micronaut.run(Micronaut.java:294)
	at io.micronaut.runtime.Micronaut.run(Micronaut.java:280)
	at example.micronaut.Application.main(Application.java:8)

FAILURE: Build failed with an exception.

Environment Information

• Operating System: Linux Mint
• Micronaut Version: 2.0.0.BUILD-SNAPSHOT
• JDK Version: 1.8

Example Application

https://github.com/micronaut-graal-tests/micronaut-management-graal

[mitchnull]

This fix strips any previous instrumentations. I don't think that was intentional. As far as I can see here you should return the original bean (executorService) instead of the unwrapped netty bean (in ExecutionServiceMetricsBinder.onCreate):

        if (unwrapped.getClass().getName().startsWith("io.netty")) {
            return unwrapped; // this should be: return executionService;
        }

With the current code, if we try to instrument a netty EventLoopGroup then we run into 2 failure scenarios:

1. the above code strips our own instrumentation if we implement InstrumentedExecutionService
2. re-introduce the original bug if we do not implement InstrumentedExecutionService as the special (and rather ugly) hack for io.netty package match fails.