Merge branch 'master' into 2.0.x

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

@@ -421,6 +421,21 @@ And you could register them like this:
 include::../../../..//spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceCustomFilterResponseInjectorTests.java[tags=configuration,indent=0]
 ----
 
+=== TraceFilter
+
+You can also modify the behaviour of the `TraceFilter` - the component that is responsible
+for processing the input HTTP request and adding tags basing on the HTTP response. You can customize
+the tags, or modify the response headers by registering your own instance of the `TraceFilter` bean.
+
+In the following example we will register the `TraceFilter` bean and we will add the
+`ZIPKIN-TRACE-ID` response header containing the current Span's trace id. Also we will
+add to the Span a tag with key `custom` and a value `tag`.
+
+[source,java]
+----
+include::../../../..//spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceFilterIntegrationTests.java[tags=response_headers,indent=0]
+----
+
 === Custom SA tag in Zipkin
 
 Sometimes you want to create a manual Span that will wrap a call to an external service which is not instrumented.

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

@@ -31,6 +31,7 @@ import javax.servlet.http.HttpServletResponse;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.cloud.sleuth.ErrorParser;
 import org.springframework.cloud.sleuth.Span;
 import org.springframework.cloud.sleuth.SpanReporter;
@@ -105,7 +106,7 @@ public class TraceFilter extends GenericFilterBean {
 	private UrlPathHelper urlPathHelper = new UrlPathHelper();
 
 	public TraceFilter(BeanFactory beanFactory) {
-		this(beanFactory, Pattern.compile(SleuthWebProperties.DEFAULT_SKIP_PATTERN));
+		this(beanFactory, skipPattern(beanFactory));
 	}
 
 	public TraceFilter(BeanFactory beanFactory, Pattern skipPattern) {
@@ -113,6 +114,22 @@ public class TraceFilter extends GenericFilterBean {
 		this.skipPattern = skipPattern;
 	}
 
+	private static Pattern skipPattern(BeanFactory beanFactory) {
+		try {
+			SkipPatternProvider patternProvider = beanFactory
+					.getBean(SkipPatternProvider.class);
+			// the null value will not happen on production but might happen in tests
+			if (patternProvider != null) {
+				return patternProvider.skipPattern();
+			}
+		} catch (NoSuchBeanDefinitionException e) {
+			if (log.isDebugEnabled()) {
+				log.debug("The default SkipPatternProvider implementation is missing, will fallback to a default value of patterns");
+			}
+		}
+		return Pattern.compile(SleuthWebProperties.DEFAULT_SKIP_PATTERN);
+	}
+
 	@Override
 	public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
 			FilterChain filterChain) throws IOException, ServletException {

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

@@ -19,6 +19,7 @@ import org.springframework.beans.factory.BeanFactory;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
@@ -88,6 +89,7 @@ public class TraceWebServletAutoConfiguration {
 	}
 
 	@Bean
+	@ConditionalOnMissingBean
 	public TraceFilter traceFilter(BeanFactory beanFactory,
 			SkipPatternProvider skipPatternProvider) {
 		return new TraceFilter(beanFactory, skipPatternProvider.skipPattern());

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

@@ -9,6 +9,7 @@ import org.junit.runner.RunWith;
 import org.mockito.BDDMockito;
 import org.mockito.Mockito;
 import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.cloud.sleuth.NoOpSpanReporter;
@@ -68,6 +69,8 @@ public class TraceFilterAlwaysSamplerIntegrationTests extends AbstractMvcIntegra
 
 	private BeanFactory beanFactory() {
 		BeanFactory beanFactory = Mockito.mock(BeanFactory.class);
+		BDDMockito.given(beanFactory.getBean(SkipPatternProvider.class))
+				.willThrow(new NoSuchBeanDefinitionException("foo"));
 		BDDMockito.given(beanFactory.getBean(Tracer.class)).willReturn(this.tracer);
 		BDDMockito.given(beanFactory.getBean(TraceKeys.class)).willReturn(this.traceKeys);
 		BDDMockito.given(beanFactory.getBean(HttpSpanExtractor.class)).willReturn(this.spanExtractor);

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

@@ -4,6 +4,8 @@ import java.util.Optional;
 import java.util.Random;
 import java.util.concurrent.CompletableFuture;
 
+import javax.servlet.http.HttpServletResponse;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.junit.After;
@@ -11,6 +13,7 @@ import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.slf4j.MDC;
+import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.actuate.autoconfigure.ManagementServerProperties;
 import org.springframework.boot.test.context.SpringBootTest;
@@ -60,7 +63,7 @@ public class TraceFilterIntegrationTests extends AbstractMvcIntegrationTest {
 	}
 
 	@Test
-	public void should_create_and_return_trace_in_HTTP_header() throws Exception {
+	public void should_create_a_trace() throws Exception {
 		whenSentPingWithoutTracingData();
 
 		then(this.spanAccumulator.getSpans()).hasSize(1);
@@ -158,6 +161,17 @@ public class TraceFilterIntegrationTests extends AbstractMvcIntegrationTest {
 		then(new ListOfSpans(this.spanAccumulator.getSpans())).hasServerSideSpansInProperOrder();
 	}
 
+	@Test
+	public void should_return_custom_response_headers_when_custom_trace_filter_gets_registered() throws Exception {
+		Long expectedTraceId = new Random().nextLong();
+
+		MvcResult mvcResult = whenSentPingWithTraceId(expectedTraceId);
+
+		then(ExceptionUtils.getLastException()).isNull();
+		then(mvcResult.getResponse().getHeader("ZIPKIN-TRACE-ID")).isEqualTo(Span.idToHex(expectedTraceId));
+		then(new ListOfSpans(this.spanAccumulator.getSpans())).hasASpanWithTagEqualTo("custom", "tag");
+	}
+
 	@Override
 	protected void configureMockMvcBuilder(DefaultMockMvcBuilder mockMvcBuilder) {
 		mockMvcBuilder.addFilters(this.traceFilter);
@@ -290,5 +304,23 @@ public class TraceFilterIntegrationTests extends AbstractMvcIntegrationTest {
 		Sampler alwaysSampler() {
 			return new AlwaysSampler();
 		}
+
+		//tag::response_headers[]
+		@Bean
+		TraceFilter myTraceFilter(BeanFactory beanFactory, final Tracer tracer) {
+			return new TraceFilter(beanFactory) {
+				@Override protected void addResponseTags(HttpServletResponse response,
+						Throwable e) {
+					// execute the default behaviour
+					super.addResponseTags(response, e);
+					// for readability we're returning trace id in a hex form
+					response.addHeader("ZIPKIN-TRACE-ID",
+							Span.idToHex(tracer.getCurrentSpan().getTraceId()));
+					// we can also add some custom tags
+					tracer.addTag("custom", "tag");
+				}
+			};
+		}
+		//end::response_headers[]
 	}
 }

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

@@ -28,6 +28,7 @@ import org.mockito.BDDMockito;
 import org.mockito.Mock;
 import org.mockito.Mockito;
 import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.cloud.sleuth.DefaultSpanNamer;
 import org.springframework.cloud.sleuth.ErrorParser;
 import org.springframework.cloud.sleuth.ExceptionMessageErrorParser;
@@ -529,6 +530,8 @@ public class TraceFilterTests {
 	}
 
 	private BeanFactory beanFactory() {
+		BDDMockito.given(beanFactory.getBean(SkipPatternProvider.class))
+				.willThrow(new NoSuchBeanDefinitionException("foo"));
 		BDDMockito.given(beanFactory.getBean(Tracer.class)).willReturn(this.tracer);
 		BDDMockito.given(beanFactory.getBean(TraceKeys.class)).willReturn(this.traceKeys);
 		BDDMockito.given(beanFactory.getBean(HttpSpanExtractor.class)).willReturn(this.spanExtractor);