Ensure HttpServerMetricsRecorder#recordServerConnectionInactive/Close is invoked for websockets

reactor-netty-http/src/main/java/reactor/netty/http/server/WebsocketServerOperations.java

@@ -90,7 +90,11 @@ final class WebsocketServerOperations extends HttpServerOperations
 		else {
 			removeHandler(NettyPipeline.HttpTrafficHandler);
 			removeHandler(NettyPipeline.AccessLogHandler);
-			removeHandler(NettyPipeline.HttpMetricsHandler);
+			ChannelHandler handler = channel.pipeline().get(NettyPipeline.HttpMetricsHandler);
+			if (handler != null) {
+				replaceHandler(NettyPipeline.HttpMetricsHandler,
+						new WebsocketHttpServerMetricsHandler((AbstractHttpServerMetricsHandler) handler));
+			}
 
 			handshakerResult = channel.newPromise();
 			HttpRequest request = new DefaultFullHttpRequest(replaced.version(),
@@ -295,4 +299,70 @@ public String selectedSubprotocol() {
 	static final AtomicIntegerFieldUpdater<WebsocketServerOperations> CLOSE_SENT =
 			AtomicIntegerFieldUpdater.newUpdater(WebsocketServerOperations.class,
 					"closeSent");
+
+	static final class WebsocketHttpServerMetricsHandler extends AbstractHttpServerMetricsHandler {
+
+		final HttpServerMetricsRecorder recorder;
+
+		WebsocketHttpServerMetricsHandler(AbstractHttpServerMetricsHandler copy) {
+			super(copy);
+			this.recorder = copy.recorder();
+		}
+
+		@Override
+		public void channelActive(ChannelHandlerContext ctx) {
+			ctx.fireChannelActive();
+		}
+
+		@Override
+		public void channelInactive(ChannelHandlerContext ctx) {
+			try {
+				if (channelOpened && recorder instanceof MicrometerHttpServerMetricsRecorder) {
+					// For custom user recorders, we don't propagate the channelInactive event, because this will be done
+					// by the ChannelMetricsHandler itself. ChannelMetricsHandler is only present when the recorder is
+					// not our MicrometerHttpServerMetricsRecorder. See HttpServerConfig class.
+					channelOpened = false;
+					// Always use the real connection local address without any proxy information
+					recorder.recordServerConnectionClosed(ctx.channel().localAddress());
+				}
+
+				if (channelActivated) {
+					channelActivated = false;
+					// Always use the real connection local address without any proxy information
+					recorder.recordServerConnectionInactive(ctx.channel().localAddress());
+				}
+			}
+			catch (RuntimeException e) {
+				// Allow request-response exchange to continue, unaffected by metrics problem
+				if (log.isWarnEnabled()) {
+					log.warn(format(ctx.channel(), "Exception caught while recording metrics."), e);
+				}
+			}
+			finally {
+				ctx.fireChannelInactive();
+			}
+		}
+
+		@Override
+		public void channelRead(ChannelHandlerContext ctx, Object msg) {
+			ctx.fireChannelRead(msg);
+		}
+
+		@Override
+		public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
+			ctx.fireExceptionCaught(cause);
+		}
+
+		@Override
+		@SuppressWarnings("FutureReturnValueIgnored")
+		public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) {
+			//"FutureReturnValueIgnored" this is deliberate
+			ctx.write(msg, promise);
+		}
+
+		@Override
+		public HttpServerMetricsRecorder recorder() {
+			return recorder;
+		}
+	}
 }

reactor-netty-http/src/test/java/reactor/netty/http/HttpMetricsHandlerTests.java

@@ -171,6 +171,8 @@ static void createSelfSignedCertificate() throws CertificateException {
 	 *  <li> /5 is used by testServerConnectionsRecorder test</li>
 	 *  <li> /6 is used by testServerConnectionsMicrometerConnectionClose test</li>
 	 *  <li> /7 is used by testServerConnectionsRecorderConnectionClose test</li>
+	 *  <li> /8 is used by testServerConnectionsWebsocketMicrometer test</li>
+	 *  <li> /9 is used by testServerConnectionsWebsocketRecorder test</li>
 	 * </ul>
 	 */
 	@BeforeEach
@@ -200,7 +202,12 @@ void setUp() {
 				             .get("/7", (req, res) -> {
 				                 checkServerConnectionsRecorder(req);
 				                 return Mono.delay(Duration.ofMillis(200)).then(res.send());
-				             }));
+				             })
+				             .get("/8", (req, res) -> res.sendWebsocket((in, out) ->
+				                     out.sendString(Mono.just("Hello World!").doOnNext(b -> checkServerConnectionsMicrometer(req)))))
+				             .get("/9", (req, res) -> res.sendWebsocket((in, out) ->
+				                     out.sendString(Mono.just("Hello World!").doOnNext(b -> checkServerConnectionsRecorder(req)))))
+				);
 
 		provider = ConnectionProvider.create("HttpMetricsHandlerTests", 1);
 		httpClient = createClient(provider, () -> disposableServer.address())
@@ -746,6 +753,28 @@ void testServerConnectionsMicrometerConnectionClose(HttpProtocol[] serverProtoco
 		}
 	}
 
+	@Test
+	void testServerConnectionsWebsocketMicrometer() throws Exception {
+		disposableServer = httpServer
+				.doOnConnection(cnx -> ServerCloseHandler.INSTANCE.register(cnx.channel()))
+				.bindNow();
+
+		String address = formatSocketAddress(disposableServer.address());
+
+		httpClient.websocket()
+		          .uri("/8")
+		          .handle((in, out) -> in.receive().aggregate().asString())
+		          .as(StepVerifier::create)
+		          .expectNext("Hello World!")
+		          .expectComplete()
+		          .verify(Duration.ofSeconds(30));
+
+		// make sure the client socket is closed on the server side before checking server metrics
+		assertThat(ServerCloseHandler.INSTANCE.awaitClientClosedOnServer()).as("awaitClientClosedOnServer timeout").isTrue();
+		assertGauge(registry, SERVER_CONNECTIONS_TOTAL, URI, HTTP, LOCAL_ADDRESS, address).hasValueEqualTo(0);
+		assertGauge(registry, SERVER_CONNECTIONS_ACTIVE, URI, HTTP, LOCAL_ADDRESS, address).hasValueEqualTo(0);
+	}
+
 	@ParameterizedTest
 	@MethodSource("httpCompatibleProtocols")
 	void testServerConnectionsRecorder(HttpProtocol[] serverProtocols, HttpProtocol[] clientProtocols,
@@ -849,6 +878,32 @@ void testServerConnectionsRecorderConnectionClose(HttpProtocol[] serverProtocols
 		}
 	}
 
+	@Test
+	void testServerConnectionsWebsocketRecorder() throws Exception {
+		ServerRecorder.INSTANCE.reset();
+		disposableServer = httpServer.metrics(true, ServerRecorder.supplier(), Function.identity())
+				.doOnConnection(cnx -> ServerCloseHandler.INSTANCE.register(cnx.channel()))
+				.bindNow();
+
+		String address = formatSocketAddress(disposableServer.address());
+
+		httpClient.websocket()
+		          .uri("/9")
+		          .handle((in, out) -> in.receive().aggregate().asString())
+		          .as(StepVerifier::create)
+		          .expectNext("Hello World!")
+		          .expectComplete()
+		          .verify(Duration.ofSeconds(30));
+
+		// make sure the client socket is closed on the server side before checking server metrics
+		assertThat(ServerCloseHandler.INSTANCE.awaitClientClosedOnServer()).as("awaitClientClosedOnServer timeout").isTrue();
+		assertThat(ServerRecorder.INSTANCE.error.get()).isNull();
+		assertThat(ServerRecorder.INSTANCE.onServerConnectionsAmount.get()).isEqualTo(0);
+		assertThat(ServerRecorder.INSTANCE.onActiveConnectionsAmount.get()).isEqualTo(0);
+		assertThat(ServerRecorder.INSTANCE.onActiveConnectionsLocalAddr.get()).isEqualTo(address);
+		assertThat(ServerRecorder.INSTANCE.onInactiveConnectionsLocalAddr.get()).isEqualTo(address);
+	}
+
 	@Test
 	void testIssue896() throws Exception {
 		disposableServer = httpServer.noSSL()