Merge remote-tracking branch 'origin/3.0.x' into main

docs/src/main/asciidoc/howto.adoc

@@ -368,30 +368,46 @@ class MyService {
 [[how-to-add-headers-to-the-http-server-response]]
 == How to Add Headers to the HTTP Server Response?
 
-Register a bean of `HttpResponseParser` type whose name is `HttpServerResponseParser.NAME`.
+Register an HTTP Filter that
 
 ====
 [source,java,indent=0]
 ----
-import org.springframework.cloud.sleuth.http.HttpResponseParser;
-import org.springframework.cloud.sleuth.instrument.web.HttpServerResponseParser;
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
+import org.springframework.cloud.sleuth.Span;
+import org.springframework.cloud.sleuth.Tracer;
+
+import javax.servlet.Filter;
+import org.springframework.web.server.WebFilter;
 
 @Configuration(proxyBeanMethods = false)
 class MyConfig {
 
-	@Bean(name = HttpServerResponseParser.NAME)
-	HttpResponseParser myHttpResponseParser() {
-		return (response, context, span) -> {
-			Object unwrap = response.unwrap();
-			if (unwrap instanceof HttpServletResponse) {
-				HttpServletResponse resp = (HttpServletResponse) unwrap;
-				resp.addHeader("MyCustom", "Header");
-			}
-		};
-	}
+		// Example of a servlet Filter for non-reactive applications
+		@Bean
+		Filter traceIdInResponseFilter(Tracer tracer) {
+			return (request, response, chain) -> {
+				Span currentSpan = tracer.currentSpan();
+				if (currentSpan != null) {
+					HttpServletResponse resp = (HttpServletResponse) response;
+					// putting trace id value in [mytraceid] response header
+					resp.addHeader("mytraceid", currentSpan.context().traceId());
+				}
+				chain.doFilter(request, response);
+			};
+		}
 
+		// Example of a reactive WebFilter for reactive applications
+		@Bean
+		WebFilter traceIdInResponseFilter(Tracer tracer) {
+			return (exchange, chain) -> {
+				Span currentSpan = tracer.currentSpan();
+				if (currentSpan != null) {
+					// putting trace id value in [mytraceid] response header
+					exchange.getResponse().getHeaders().add("mytraceid", currentSpan.context().traceId());
+				}
+				return chain.filter(exchange);
+			};
+		}
 }
 
 ----

tests/brave/spring-cloud-sleuth-instrumentation-webflux-tests/src/test/java/org/springframework/cloud/sleuth/brave/instrument/web/TraceWebFluxTests.java

@@ -44,6 +44,7 @@ import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.reactive.function.server.RouterFunction;
 import org.springframework.web.reactive.function.server.RouterFunctions;
 import org.springframework.web.reactive.function.server.ServerResponse;
+import org.springframework.web.server.WebFilter;
 
 import static org.assertj.core.api.BDDAssertions.then;
 
@@ -69,6 +70,8 @@ public class TraceWebFluxTests {
 		ClientResponse response = whenRequestIsSent(port, "/api/c2/10");
 		// then
 		thenSpanWasReportedWithTags(spans, response);
+		// then #2002
+		then(response.headers().header("mytraceid")).isNotEmpty();
 		clean(spans, controller2);
 
 		// when
@@ -213,6 +216,17 @@ public class TraceWebFluxTests {
 					serverRequest -> ServerResponse.ok().bodyValue(serverRequest.pathVariable("id"))).build();
 		}
 
+		@Bean
+		WebFilter traceIdInResponseFilter(Tracer tracer) {
+			return (exchange, chain) -> {
+				Span currentSpan = tracer.currentSpan();
+				if (currentSpan != null) {
+					exchange.getResponse().getHeaders().add("mytraceid", currentSpan.context().traceIdString());
+				}
+				return chain.filter(exchange);
+			};
+		}
+
 	}
 
 	@RestController

tests/common/src/main/java/org/springframework/cloud/sleuth/instrument/web/HttpServerParserTests.java

@@ -19,6 +19,7 @@ package org.springframework.cloud.sleuth.instrument.web;
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import javax.servlet.Filter;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
@@ -40,6 +41,7 @@ import org.springframework.cloud.sleuth.test.TestSpanHandler;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
+import org.springframework.http.ResponseEntity;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
@@ -72,8 +74,11 @@ public abstract class HttpServerParserTests {
 
 	@Test
 	public void should_set_tags_via_server_parsers() {
-		BDDAssertions.then(new RestTemplate().getForObject("http://localhost:" + this.port + "/hello", String.class))
-				.isEqualTo("hello");
+		ResponseEntity<String> entity = new RestTemplate().getForEntity("http://localhost:" + this.port + "/hello",
+				String.class);
+
+		BDDAssertions.then(entity.getBody()).isEqualTo("hello");
+		BDDAssertions.then(entity.getHeaders()).containsKey("mytraceid");
 
 		Awaitility.await()
 				.untilAsserted(() -> then(serverSideTags()).containsEntry("ServerRequest", "Tag")
@@ -151,6 +156,18 @@ public abstract class HttpServerParserTests {
 			};
 		}
 
+		@Bean
+		Filter traceIdInResponseFilter(Tracer tracer) {
+			return (request, response, chain) -> {
+				Span currentSpan = tracer.currentSpan();
+				if (currentSpan != null) {
+					HttpServletResponse resp = (HttpServletResponse) response;
+					resp.addHeader("mytraceid", currentSpan.context().traceId());
+				}
+				chain.doFilter(request, response);
+			};
+		}
+
 	}
 	// end::server_parser_config[]