https://github.com/spring-cloud/spring-cloud-sleuth/issues/597

Fix Http headers as tags

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/HttpTraceKeysInjector.java

@@ -73,8 +73,9 @@ public class HttpTraceKeysInjector {
 
 	private void addRequestTagsFromHeaders(Map<String, ? extends Collection<String>> headers) {
 		for (String name : this.traceKeys.getHttp().getHeaders()) {
-			for (Map.Entry<String, ? extends Collection<String>> entry : headers.entrySet()) {
-				addTagForEntry(name, entry.getValue());
+			Collection<String> values = headers.get(name);
+			if(values != null) {
+				addTagForEntry(name, values);
 			}
 		}
 	}

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/HttpTraceKeysInjectorUnitTests.java

@@ -0,0 +1,67 @@
+package org.springframework.cloud.sleuth.instrument.web;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import java.net.URL;
+import java.util.Arrays;
+import java.util.Map;
+import java.util.Random;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.cloud.sleuth.DefaultSpanNamer;
+import org.springframework.cloud.sleuth.NoOpSpanReporter;
+import org.springframework.cloud.sleuth.Span;
+import org.springframework.cloud.sleuth.SpanNamer;
+import org.springframework.cloud.sleuth.SpanReporter;
+import org.springframework.cloud.sleuth.TraceKeys;
+import org.springframework.cloud.sleuth.Tracer;
+import org.springframework.cloud.sleuth.log.Slf4jSpanLogger;
+import org.springframework.cloud.sleuth.log.SpanLogger;
+import org.springframework.cloud.sleuth.sampler.AlwaysSampler;
+import org.springframework.cloud.sleuth.trace.DefaultTracer;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
+
+
+public class HttpTraceKeysInjectorUnitTests {
+	TraceKeys traceKeys = new TraceKeys();
+	private SpanNamer spanNamer = new DefaultSpanNamer();
+	private SpanLogger spanLogger = new Slf4jSpanLogger("skip");
+	private SpanReporter spanReporter = new NoOpSpanReporter();
+	AlwaysSampler sampler = new AlwaysSampler();
+	Tracer tracer = new DefaultTracer(sampler, new Random(), spanNamer, spanLogger, spanReporter, traceKeys);
+	HttpTraceKeysInjector injector;
+	
+	@Before
+	public void setup() {
+		assertNotNull(tracer);
+		injector = new HttpTraceKeysInjector(tracer, traceKeys);
+	}
+	
+	@Test
+	public void testHttpAttributes() throws Exception {
+		traceKeys.getHttp().setHeaders(Arrays.asList("Accept", "User-Agent", "Content-Type"));;
+		
+		URL url = new URL("http://localhost:8080/");
+		HttpHeaders headers = new HttpHeaders();
+		headers.add("User-Agent", "Test");
+		headers.put("Accept", Arrays.asList(MediaType.TEXT_PLAIN_VALUE, MediaType.TEXT_XML_VALUE));
+		headers.add("Content-Length", "0");
+		headers.add("X-B3-TraceId","3bb9a1fa9e70fdbd763261a53162f330");
+		headers.add("X-B3-SpanId", "763261a53162f330");
+		headers.add("X-B3-Sampled","1");
+		headers.add("X-Span-Name", "http:/");
+		
+		Span span = tracer.createSpan("TestSpan", sampler);
+		injector.addRequestTags(url.toString(), url.getHost(), url.getPath(), HttpMethod.GET.name(), headers );
+		Map<String, String> tags = span.tags();
+		assertEquals("Test", tags.get("http.user-agent"));
+		assertEquals("'text/plain','text/xml'", tags.get("http.accept"));
+		assertNull(tags.get("http.content-type"));
+
+	}
+}