Merge branch '1.3.x'

docs/src/main/asciidoc/spring-cloud-sleuth.adoc

@@ -1147,6 +1147,38 @@ To block this feature, set `spring.sleuth.messaging.enabled` to `false`.
 We instrument the Zuul Ribbon integration by enriching the Ribbon requests with tracing information.
 To disable Zuul support, set the `spring.sleuth.zuul.enabled` property to `false`.
 
+=== Spring Cloud Function
+
+Sleuth works out of the box with Spring Cloud Function. Since functions
+might be short living, it's best to make the Zipkin span reporting synchronous.
+Just define a `Reporter<Span>` bean as presented below:
+
+[source,java]
+----
+@Configuration
+class ReporterConfiguration {
+	@Bean
+	public Reporter<Span> reporter(
+			SpanMetricReporter spanMetricReporter,
+			ZipkinProperties zipkin,
+			Sender sender
+	) {
+		final AsyncReporter<Span> reporter = AsyncReporter.builder(sender)
+				.queuedMaxSpans(1000)
+				.messageTimeout(zipkin.getMessageTimeout(), TimeUnit.SECONDS)
+				.metrics(new ReporterMetricsAdapter(spanMetricReporter))
+				.build(zipkin.getEncoder());
+		return new Reporter<Span>() {
+			@Override public void report(Span span) {
+				reporter.report(span);
+				// make the reporter synchronous
+				reporter.flush();
+			}
+		};
+	}
+}
+----
+
 == Running examples
 
 You can see the running examples deployed in the https://run.pivotal.io/[Pivotal Web Services].

spring-cloud-sleuth-zipkin/src/main/java/org/springframework/cloud/sleuth/zipkin2/ZipkinAutoConfiguration.java

@@ -80,11 +80,17 @@ public class ZipkinAutoConfiguration {
 			ZipkinProperties zipkin,
 			Sender sender
 	) {
-		return AsyncReporter.builder(sender)
-				.queuedMaxSpans(1000) // historical constraint. Note: AsyncReporter supports memory bounds
+		final AsyncReporter<Span> reporter = AsyncReporter.builder(sender).queuedMaxSpans(
+				1000) // historical constraint. Note: AsyncReporter supports memory bounds
 				.messageTimeout(zipkin.getMessageTimeout(), TimeUnit.SECONDS)
 				.metrics(reporterMetrics)
 				.build(zipkin.getEncoder());
+		return new Reporter<Span>() {
+			@Override public void report(Span span) {
+				reporter.report(span);
+				reporter.flush();
+			}
+		};
 	}
 
 	@Bean