We are using reactor netty server as a standalone application not as part of spring boot
Our server comes up fine and serves request as expected but at the time of shutdown with a SIGTERM signal, we are observing that the server sends FIN,ACK signals to connected clients instead of GOAWAY.

Expected Behavior

Server should close gracefully sending GOAWAY singnals on all the connections

Actual Behavior

Server sends FIN,ACK instead of GOAWAY

Steps to Reproduce

PFA a reproducible example. It is gradle project.

It simply contains one Main class which servers a GET API on 8080 port with uri '/'

curl -ivX GET localhost:8080/ --http2-prior-knowledge
You can use the above curl request to use it

To simulate, I used a 3rd party http client called vegeta which constantly sends traffic on 1 connection
and took the tcpdump using:
tcpdump -i localinterface port 8080
i kill the running java process using:
kill -15 processid
Step1: start the server
Step2:start capturing tcpdump
Step3:start the traffic using vegeta client(i ran 1 message per second)
Step4:kill the process while traffic is still running

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println("starting server");
		LoopResources loop = LoopResources.create("event-loop");
		Consumer<Builder> h2Settings= s -> s.maxConcurrentStreams(1000);
	HttpServer server = HttpServer.create().port(8080)
			.protocol(HttpProtocol.H2C) // Set HTTP/2 protocol//HttpProtocol.H2 is for TLS
            .runOn(loop)
            .channelGroup(new DefaultChannelGroup(new DefaultEventExecutor()))
            //.wiretap(true)
            .http2Settings(h2Settings)
            .idleTimeout(Duration.ofMinutes(10))
            .route(routes ->
            routes.get("/",(req,res)->{
            	System.out.println("request processing");
            	return res.status(HttpResponseStatus.ACCEPTED).send(Mono.just(Unpooled.wrappedBuffer("{abcde}".getBytes())));
            }));
	DisposableServer disposableServer = server.bindNow();
	System.out.println("after");
    Runtime.getRuntime().addShutdownHook(new Thread(()-> {
    	System.out.println("shutdown");
    	disposableServer.disposeNow();
    	System.out.println("disposed");
    }));    
	disposableServer.onDispose().block();
	System.out.println("disposed completely");
	}

reactorgraceful.zip

Your Environment

version:
implementation("io.projectreactor.netty:reactor-netty-http:1.1.12")

• Reactor version(s) used:1.1.12
• Other relevant libraries versions (eg. netty, ...):
• JVM version (java -version):21.0.7
• OS and version (eg. uname -a):linux