Spring Missing Netty native image hints for SelectorProvider

After compiled application to graalvm native image, and set log level for io.netty to TRACE, such exception will show up(which can't reproduce in jvm application):

2023-08-31T01:27:05.755+08:00 TRACE 55266 --- [           main] io.netty.channel.nio.NioEventLoop        : instrumented a special java.util.Set into: sun.nio.ch.EPollSelectorImpl@28fee399
2023-08-31T01:27:05.755+08:00 DEBUG 55266 --- [           main] i.n.c.socket.nio.SelectorProviderUtil    : SelectorProvider.openServerSocketChannel(ProtocolFamily) not available, will use default

java.lang.NoSuchMethodException: java.nio.channels.spi.SelectorProvider.openServerSocketChannel(java.net.ProtocolFamily)
        at java.base@17.0.8/java.lang.Class.checkMethod(DynamicHub.java:1038) ~[monolith-service:na]
        at java.base@17.0.8/java.lang.Class.getMethod(DynamicHub.java:1023) ~[monolith-service:na]
        at io.netty.channel.socket.nio.SelectorProviderUtil.findOpenMethod(SelectorProviderUtil.java:39) ~[na:na]
        at io.netty.channel.socket.nio.NioServerSocketChannel.<clinit>(NioServerSocketChannel.java:57) ~[monolith-service:4.1.97.Final]
        at reactor.netty.resources.DefaultLoopNIO.getChannel(DefaultLoopNIO.java:45) ~[na:na]
        at reactor.netty.resources.LoopResources.onChannel(LoopResources.java:243) ~[monolith-service:1.1.10]
        at reactor.netty.tcp.TcpResources.onChannel(TcpResources.java:251) ~[monolith-service:1.1.10]
        at reactor.netty.transport.TransportConfig.lambda$connectionFactory$1(TransportConfig.java:277) ~[monolith-service:1.1.10]
        at reactor.netty.transport.TransportConnector.doInitAndRegister(TransportConnector.java:277) ~[na:na]
        at reactor.netty.transport.TransportConnector.bind(TransportConnector.java:87) ~[na:na]
        at reactor.netty.transport.ServerTransport.lambda$bind$0(ServerTransport.java:115) ~[monolith-service:1.1.10]
        at reactor.core.publisher.MonoCreate.subscribe(MonoCreate.java:58) ~[na:na]
        at reactor.core.publisher.Mono.subscribe(Mono.java:4495) ~[monolith-service:3.5.9]
        at reactor.core.publisher.Mono.block(Mono.java:1737) ~[monolith-service:3.5.9]
        at reactor.netty.transport.ServerTransport.bindNow(ServerTransport.java:149) ~[monolith-service:1.1.10]
        at reactor.netty.transport.ServerTransport.bindNow(ServerTransport.java:134) ~[monolith-service:1.1.10]
        at org.springframework.boot.web.embedded.netty.NettyWebServer.startHttpServer(NettyWebServer.java:145) ~[monolith-service:3.1.3]
        at org.springframework.boot.web.embedded.netty.NettyWebServer.start(NettyWebServer.java:100) ~[monolith-service:3.1.3]
        at org.springframework.boot.web.reactive.context.WebServerManager.start(WebServerManager.java:55) ~[na:na]
        at org.springframework.boot.web.reactive.context.WebServerStartStopLifecycle.start(WebServerStartStopLifecycle.java:41) ~[na:na]
        at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:179) ~[monolith-service:6.0.11]
        at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:357) ~[monolith-service:6.0.11]
        at java.base@17.0.8/java.lang.Iterable.forEach(Iterable.java:75) ~[monolith-service:na]
        at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:156) ~[monolith-service:6.0.11]
        at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:124) ~[monolith-service:6.0.11]
        at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:958) ~[monolith-service:6.0.11]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:611) ~[monolith-service:6.0.11]
        at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:66) ~[monolith-service:3.1.3]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:734) ~[monolith-service:3.1.3]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:436) ~[monolith-service:3.1.3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) ~[monolith-service:3.1.3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306) ~[monolith-service:3.1.3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1295) ~[monolith-service:3.1.3]
        at com.hkmci.masterspace.monolith.ApplicationKt.main(Application.kt:15) ~[monolith-service:na]
        at com.hkmci.masterspace.monolith.ApplicationKt.main(Application.kt) ~[monolith-service:na]

Netty code in io.netty.channel.socket.nio.SelectorProviderUtil:

@SuppressJava6Requirement(reason = "Usage guarded by java version check")
static Method findOpenMethod(String methodName) {
    if (PlatformDependent.javaVersion() >= 15) {
        try {
            return SelectorProvider.class.getMethod(methodName, java.net.ProtocolFamily.class);
        } catch (Throwable e) {
            logger.debug("SelectorProvider.{}(ProtocolFamily) not available, will use default", methodName, e);
        }
    }
    return null;
}

Netty do reflection operation on SelectorProvider, and it's not coverd by Spring AOT.

In fact, Netty will invoke two methods in SelectorProvider:

public SocketChannel openSocketChannel(ProtocolFamily family)
public ServerSocketChannel openServerSocketChannel(ProtocolFamily family)

Adding reflection hints for these two method can eliminate the exception.

Comment From: bclozel

Could you create this issue against the Netty project directly? Netty is managing its own GraalVM metadata directly in the project (see here for example). For other, non-Spring libraries, please check the library itself or the GraalVM reachability metadata repository.