I have a spring reactive based Microservice which is using Netty Server version 4.1.101.Final. It was working completely fine and processing all the HTTP requests which I fire . Now I want to catch the connection-ids to figure out which connection is getting used and which is getting closed. For this I have written a custom Connection Logging handler. Following is my ConnectionLoggingHandler :

public class ConnectionLoggingHandler extends ChannelInboundHandlerAdapter{
    private static final AtomicInteger connectionIdCounter = new AtomicInteger(0);
    
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception{
        int connectionId=connectionIdCounter.incrementAndGet();
        System.out.println("Connection established : ID = " + connectionId);
        ctx.channel().attr(AttributeKey.valueOf("connectionId")).set(connectionId);
        super.channelActive(ctx);
    }
    
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception{
        //retrieve connectionID
        Integer connectionId = (Integer) ctx.channel().attr(AttributeKey.valueOf("connectionId")).get();
        if(connectionId!=null){
          System.out.println("Connection closed : ID = " + connectionId);  
        }
        super.channelInactive(ctx);
    }
    
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception{
        //retrieve connectionID
        Integer connectionId = (Integer) ctx.channel().attr(AttributeKey.valueOf("connectionId")).get();
        if(connectionId!=null){
          System.out.println("Exception in Connection: ID = " + connectionId);  
        }
        cause.printStackTrace();
        ctx.close();
    }
}

Now I want to add this handler to my Netty Server. I tried this using two ways.

Code for Custom Netty Server:

public class CustomNettyServer{
    private int port =8080;
    
    @PostConstruct
    public void startServer() throws InterruptedException{
        EventLoopGroup boss= new NioEventLoopGroup();
        EventLoopGroup worker=new NioEventLoopGroup();
        try{
            ServerBootstrap bootstrap new ServerBootstrap();
            bootstrap.group(boss,worker)
                .channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer<Channel>(){
                    @Override
                    protected void initChannel(Channel ch) throws Exception{
                        ch.pipeline().addLast(new HttpServerCodec(),new HttpRequestDecoder(),new HttpContentDecompressor(),new HttpResponseEncoder(),new HttpContentCompressor(),new HttpObjectAggregator(512*1024),new ConnectionLoggingHandler());
                        
                    }
                });
            Channel channel = bootstarp.bind(port).sync().channel();
            channel.closeFuture().sync();
        }
        finally{
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }
    }
}

When I use this server, then I can see the logs present in my custom handler when I hit a request through postman for establishment of connection. But my HTTP request is not getting processed.
It says Discarded inbound message. Please check your pipeline configuration. I don’t know what am I missing here.

Then I also tried another way to customize my netty server. Below is my code for CustomNettyServer.

public class CustomNettyServer implements WebServerFactoryCustomizer<NettyReactiveWebServerFactory>{
    @Override
    public void customize(NettyReactiveWebServerFactory factory){
        factory.addServerCustomizers(server->
        server.tcpConfiguration(tcp->
        tcp.doOnConnection(connection->
        connection.addHandlerLast(new ConnectionLoggingHandler()))));
    }
}

Using this method, I cannot see logs getting printed due to my ConnectionLoggingHandler whenever I hit a request and the request is getting prcoessed successfully. I can see Handler getting added to the pipeline when the request is made and removed when the request is served. But the logs are not getting generated. I have also kept the logging level to DEBUG.

I don’t know what I am doing wrong in these two ways and I am stuck here.
So I want to know how can I get the logs for the Connection-IDs which are being opened, used and closed.
Thanks.