Add zuul instrumentation

pom.xml

@@ -27,7 +27,6 @@
 
 	<modules>
 		<module>spring-cloud-sleuth-core</module>
-		<module>spring-cloud-sleuth-zipkin</module>
 		<module>spring-cloud-sleuth-sample</module>
 		<module>docs</module>
 	</modules>
@@ -155,6 +154,11 @@
 				<artifactId>hystrix-core</artifactId>
 				<version>1.4.5</version>
 			</dependency>
+			<dependency>
+				<groupId>com.netflix.zuul</groupId>
+				<artifactId>zuul-core</artifactId>
+				<version>1.0.28</version>
+			</dependency>
 			<dependency>
 				<groupId>org.aspectj</groupId>
 				<artifactId>aspectjrt</artifactId>

spring-cloud-sleuth-core/pom.xml

@@ -47,6 +47,11 @@
 			<artifactId>hystrix-core</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>com.netflix.zuul</groupId>
+			<artifactId>zuul-core</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>io.reactivex</groupId>
 			<artifactId>rxjava</artifactId>

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

@@ -86,6 +86,7 @@ public class TraceFilter extends OncePerRequestFilter {
 				// Send new span id back
 				addToResponseIfNotPresent(response, SPAN_ID_NAME, span.getSpanId());
 
+				//TODO: trace description?
 				traceScope = trace.startSpan("traceFilter", span);
 			}
 			else {

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/zuul/TracePostFilter.java

@@ -0,0 +1,46 @@
+package org.springframework.cloud.sleuth.instrument.zuul;
+
+import org.springframework.cloud.sleuth.Trace;
+import org.springframework.cloud.sleuth.TraceScope;
+
+import com.netflix.zuul.ZuulFilter;
+import com.netflix.zuul.context.RequestContext;
+
+/**
+ * @author Spencer Gibb
+ */
+public class TracePostFilter extends ZuulFilter {
+
+	private Trace trace;
+
+	public TracePostFilter(Trace trace) {
+		this.trace = trace;
+	}
+
+	@Override
+	public String filterType() {
+		return "post";
+	}
+
+	@Override
+	public int filterOrder() {
+		return 0;
+	}
+
+	@Override
+	public boolean shouldFilter() {
+		return true;
+	}
+
+	@Override
+	public Object run() {
+		TraceScope traceScope = (TraceScope) RequestContext.getCurrentContext().get(
+				"traceScope");
+
+		if (traceScope != null) {
+			traceScope.close();
+		}
+
+		return null;
+	}
+}

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/zuul/TracePreFilter.java

@@ -0,0 +1,72 @@
+package org.springframework.cloud.sleuth.instrument.zuul;
+
+import static org.springframework.cloud.sleuth.Trace.SPAN_ID_NAME;
+import static org.springframework.cloud.sleuth.Trace.TRACE_ID_NAME;
+import static org.springframework.util.StringUtils.hasText;
+
+import java.util.Collections;
+
+import javax.servlet.http.HttpServletRequest;
+
+import org.springframework.cloud.sleuth.MilliSpan;
+import org.springframework.cloud.sleuth.Span;
+import org.springframework.cloud.sleuth.Trace;
+import org.springframework.cloud.sleuth.TraceScope;
+
+import com.netflix.zuul.ZuulFilter;
+import com.netflix.zuul.context.RequestContext;
+
+/**
+ * @author Spencer Gibb
+ */
+public class TracePreFilter extends ZuulFilter {
+
+	private Trace trace;
+
+	public TracePreFilter(Trace trace) {
+		this.trace = trace;
+	}
+
+	@Override
+	public String filterType() {
+		return "pre";
+	}
+
+	@Override
+	public int filterOrder() {
+		return 0;
+	}
+
+	@Override
+	public boolean shouldFilter() {
+		return true;
+	}
+
+	@Override
+	public Object run() {
+		RequestContext context = RequestContext.getCurrentContext();
+		HttpServletRequest request = context.getRequest();
+
+		String spanId = request.getHeader(SPAN_ID_NAME);
+		String traceId = request.getHeader(TRACE_ID_NAME);
+		TraceScope traceScope = null;
+		if (hasText(spanId) && hasText(traceId)) {
+
+			Span span = MilliSpan.builder().traceId(traceId)
+					.parents(Collections.singletonList(spanId))
+					// TODO: use parent() when lombok plugin supports it
+					.build();
+
+			// TODO: trace description?
+			traceScope = trace.startSpan("traceZuulFilter", span);
+		}
+		else {
+			traceScope = trace.startSpan("traceZuulFilter");
+
+		}
+
+		context.set("traceScope", traceScope);
+
+		return null;
+	}
+}

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/zuul/TraceZuulAutoConfiguration.java

@@ -0,0 +1,28 @@
+package org.springframework.cloud.sleuth.instrument.zuul;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.cloud.sleuth.Trace;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import com.netflix.zuul.ZuulFilter;
+
+/**
+ * @author Spencer Gibb
+ */
+@Configuration
+@ConditionalOnClass(ZuulFilter.class)
+@ConditionalOnBean(Trace.class)
+public class TraceZuulAutoConfiguration {
+
+	@Bean
+	public TracePreFilter tracePreFilter(Trace trace) {
+		return new TracePreFilter(trace);
+	}
+
+	@Bean
+	public TracePostFilter tracePostFilter(Trace trace) {
+		return new TracePostFilter(trace);
+	}
+}