Added support for WebClient

Author: marcingrzejszczak

build.gradle

@@ -45,6 +45,7 @@ configure(subprojects) {
 	repositories {
 		mavenLocal()
 		jcenter()
+		mavenCentral()
 		maven {
 			url "http://repo.spring.io/snapshot"
 		}

service1/src/main/java/io/spring/cloud/sleuth/docs/service1/Application.java

@@ -8,15 +8,13 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Primary;
 import org.springframework.web.client.RestTemplate;
+import org.springframework.web.reactive.function.client.WebClient;
 import zipkin2.reporter.Sender;
 
 @SpringBootApplication
 public class Application {
 
-	@Bean
-	RestTemplate restTemplate() {
-		return new RestTemplate();
-	}
+	@Bean WebClient webClient() { return WebClient.create(); }
 
 	public static void main(String... args) {
 		new SpringApplication(Application.class).run(args);

service1/src/main/java/io/spring/cloud/sleuth/docs/service1/Service2Client.java

@@ -13,6 +13,8 @@
 import org.springframework.stereotype.Component;
 import org.springframework.util.StringUtils;
 import org.springframework.web.client.RestTemplate;
+import org.springframework.web.reactive.function.client.ClientResponse;
+import org.springframework.web.reactive.function.client.WebClient;
 
 /**
  * @author Marcin Grzejszczak
@@ -22,14 +24,14 @@ class Service2Client {
 
 	private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
-	private final RestTemplate restTemplate;
+	private final WebClient webClient;
 	private final String serviceAddress;
 	private final Tracer tracer;
 
-	Service2Client(RestTemplate restTemplate,
+	Service2Client(WebClient webClient,
 			@Value("${service2.address:localhost:8082}") String serviceAddress,
 			Tracer tracer) {
-		this.restTemplate = restTemplate;
+		this.webClient = webClient;
 		this.serviceAddress = serviceAddress;
 		this.tracer = tracer;
 	}
@@ -49,7 +51,11 @@ public String start() throws InterruptedException {
 		span.annotate("baggage_set");
 		span.tag(baggageKey, baggageValue);
 		log.info("Hello from service1. Calling service2");
-		String response = restTemplate.getForObject("http://" + serviceAddress + "/foo", String.class);
+		String response = webClient.get()
+				.uri("http://" + serviceAddress + "/foo")
+				.exchange()
+				.block()
+				.bodyToMono(String.class).block();
 		Thread.sleep(100);
 		log.info("Got response from service2 [{}]", response);
 		log.info("Service1: Baggage for [key] is [" + ExtraFieldPropagation.get("key") + "]");
@@ -61,7 +67,14 @@ String timeout(@SpanTag("someTag") String tag) {
 		try {
 			Thread.sleep(300);
 			log.info("Hello from service1. Calling service2 - should end up with read timeout");
-			String response = restTemplate.getForObject("http://" + serviceAddress + "/readtimeout", String.class);
+			String response = webClient.get()
+					.uri("http://" + serviceAddress + "/readtimeout")
+					.retrieve()
+					.onStatus(httpStatus -> httpStatus.isError(), clientResponse -> {
+						throw new IllegalStateException("Exception!");
+					})
+					.bodyToMono(String.class)
+					.block();
 			log.info("Got response from service2 [{}]", response);
 			return response;
 		} catch (Exception e) {