Merge pull request sqshq#29 from thanus/master

Add Spring Cloud Sleuth for distributed tracing

README.md

@@ -204,6 +204,24 @@ Let's see our system behavior under load: Account service calls Statistics servi
 Centralized logging can be very useful when attempting to identify problems in a distributed environment. Elasticsearch, Logstash and Kibana stack lets you search and analyze your logs, utilization and network activity data with ease.
 Ready-to-go Docker configuration described [in my other project](http://github.com/sqshq/ELK-docker).
 
+### Distributed tracing
+
+Analyzing problems in distributed systems can be difficult, for example, tracing requests that propagate from one microservice to another. It can be quite a challenge to try to find out how a request travels through the system, especially if you don't have any insight into the implementation of a microservice. Even when there is logging, it is hard to tell which action correlates to a single request.
+
+[Spring Cloud Sleuth](https://cloud.spring.io/spring-cloud-sleuth/) solves this problem by providing support for distributed tracing. It adds two types of IDs to the logging: traceId and spanId. The spanId represents a basic unit of work, for example sending an HTTP request. The traceId contains a set of spans forming a tree-like structure. For example, with a distributed big-data store, a trace might be formed by a PUT request. Using traceId and spanId for each operation we know when and where our application is as it processes a request, making reading our logs much easier. 
+
+The logs are as follows, notice the `[appname,traceId,spanId,exportable]` entries from the Slf4J MDC:
+
+```text
+2018-07-26 23:13:49.381  WARN [gateway,3216d0de1384bb4f,3216d0de1384bb4f,false] 2999 --- [nio-4000-exec-1] o.s.c.n.z.f.r.s.AbstractRibbonCommand    : The Hystrix timeout of 20000ms for the command account-service is set lower than the combination of the Ribbon read and connect timeout, 80000ms.
+2018-07-26 23:13:49.562  INFO [account-service,3216d0de1384bb4f,404ff09c5cf91d2e,false] 3079 --- [nio-6000-exec-1] c.p.account.service.AccountServiceImpl   : new account has been created: test
+```
+
+- *`appname`*: The name of the application that logged the span from the property `spring.application.name`
+- *`traceId`*: This is an ID that is assigned to a single request, job, or action
+- *`spanId`*: The ID of a specific operation that took place
+- *`exportable`*: Whether the log should be exported to [Zipkin](https://zipkin.io/)
+
 ## Security
 
 An advanced security configuration is beyond the scope of this proof-of-concept project. For a more realistic simulation of a real system, consider to use https, JCE keystore to encrypt Microservices passwords and Config server properties content (see [documentation](http://cloud.spring.io/spring-cloud-config/spring-cloud-config.html#_security) for details).

account-service/pom.xml

@@ -40,6 +40,10 @@
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-starter-sleuth</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-data-mongodb</artifactId>

auth-service/pom.xml

@@ -40,6 +40,10 @@
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
         </dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-starter-sleuth</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>

gateway/pom.xml

@@ -32,6 +32,10 @@
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-starter-sleuth</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>

notification-service/pom.xml

@@ -40,6 +40,10 @@
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-starter-sleuth</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-data-mongodb</artifactId>

statistics-service/pom.xml

@@ -40,6 +40,10 @@
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-starter-sleuth</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-data-mongodb</artifactId>