How to make Armeria exit on an `Address already in use` error?

Question

How do I make sure that my program exits when Armeria fails to start because of an Address already in use error?

I have the following code:

import com.linecorp.armeria.common.HttpRequest;
import com.linecorp.armeria.common.HttpResponse;
import com.linecorp.armeria.server.AbstractHttpService;
import com.linecorp.armeria.server.Server;
import com.linecorp.armeria.server.ServerBuilder;
import com.linecorp.armeria.server.ServiceRequestContext;
import java.util.concurrent.CompletableFuture;

public class TestMain {

    public static void main(String[] args) {
        ServerBuilder sb = Server.builder();
        sb.http(8080);

        sb.service("/greet/{name}", new AbstractHttpService() {
            @Override
            protected HttpResponse doGet(ServiceRequestContext ctx, HttpRequest req) throws Exception {
                String name = ctx.pathParam("name");
                return HttpResponse.of("Hello, %s!", name);
            }
        });

        Server server = sb.build();
        CompletableFuture<Void> future = server.start();
        future.join();
    }

}

When I run it once everything is fine. But when I run it the second time I get an Address already in use error, which is of course expected, but the program doesn't terminate on its own. This may be how it is supposed to be, but how do I make sure that it terminates upon errors during initialization?

$ gradle run

> Task :run
14:36:04.811 [main] DEBUG io.netty.util.internal.logging.InternalLoggerFactory - Using SLF4J as the default logging framework
14:36:04.815 [main] DEBUG io.netty.util.internal.PlatformDependent0 - -Dio.netty.noUnsafe: false
14:36:04.816 [main] DEBUG io.netty.util.internal.PlatformDependent0 - Java version: 8
14:36:04.817 [main] DEBUG io.netty.util.internal.PlatformDependent0 - sun.misc.Unsafe.theUnsafe: available
14:36:04.817 [main] DEBUG io.netty.util.internal.PlatformDependent0 - sun.misc.Unsafe.copyMemory: available
14:36:04.818 [main] DEBUG io.netty.util.internal.PlatformDependent0 - java.nio.Buffer.address: available
...
14:36:05.064 [globalEventExecutor-3-1] DEBUG io.netty.buffer.PooledByteBufAllocator - -Dio.netty.allocator.maxCachedByteBuffersPerChunk: 1023
14:36:05.068 [globalEventExecutor-3-1] DEBUG io.netty.buffer.ByteBufUtil - -Dio.netty.allocator.type: pooled
14:36:05.068 [globalEventExecutor-3-1] DEBUG io.netty.buffer.ByteBufUtil - -Dio.netty.threadLocalDirectBufferSize: 0
14:36:05.068 [globalEventExecutor-3-1] DEBUG io.netty.buffer.ByteBufUtil - -Dio.netty.maxThreadLocalCharBufferSize: 16384
Exception in thread "main" java.util.concurrent.CompletionException: io.netty.channel.unix.Errors$NativeIoException: bind(..) failed: Address already in use
        at java.util.concurrent.CompletableFuture.encodeRelay(CompletableFuture.java:326)
        at java.util.concurrent.CompletableFuture.completeRelay(CompletableFuture.java:338)
        at java.util.concurrent.CompletableFuture.uniRelay(CompletableFuture.java:911)
        at java.util.concurrent.CompletableFuture.uniCompose(CompletableFuture.java:953)
        at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:926)
        at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474)
        at java.util.concurrent.CompletableFuture.postFire(CompletableFuture.java:561)
        at java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:739)
        at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:442)
        at io.netty.util.concurrent.GlobalEventExecutor$TaskRunner.run(GlobalEventExecutor.java:250)
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
        at java.lang.Thread.run(Thread.java:748)
Caused by: io.netty.channel.unix.Errors$NativeIoException: bind(..) failed: Address already in use
<==========---> 80% EXECUTING [6s]
> :run
^C

Answer 1

It's a bug in Armeria, where Netty event loop threads are not terminated when a Server fails to start up. Here's the fix PR, which should be part of the next release (0.97.0): https://github.com/line/armeria/pull/2288