Spring & Spring Boot stuff

Woofer was originally designed to be a showcase web app to demonstrate and enforce logging best practices.

But actually it is also a quite advanced Spring Boot-based microservices project sample that could be used as a bootstrap to create a microservices application.

This page highlights Spring & Spring Boot modules used in Woofer.

Woofer's microservices

Woofer heavily relies on Spring Boot, and Spring Cloud to implement a microservices architecture.

It involves the following components:

Woofer's profiles

By default, when launching Woofer services locally with no profile, it will use a memory database (h2), output Java and Http logs to the console.

But Woofer has several Spring Boot profiles to adapt to several environments.

Profile Description Required environment variables
logstash used to ship Java and Http logs to a Logstash server in JSON native format $LOGSTASH_HOST, $LOGSTASH_PORT and optionally $MD_PROJECT (project ID metadata)
h2 uses h2 as database (mem or file) $H2_DATASOURCE_URL (default in memory), $H2_USER (default sa) and $H2_PASSWORD (default none)
mysql uses MySQL or MariaDB as database $MYSQL_DATASOURCE_URL (default on localhost), $MYSQL_USER (default root) and $MYSQL_PASSWORD (default none)
zipkin activates distributed tracing with a Zipkin server $ZIPKIN_URL and $ZIPKIN_SAMPLING (a ratio)
openshift adapts the Woofer configuration to an OpenShift v3 environment (work in progress) none
jmx exposes Spring Boot Actuator metrics through JMX none

Spring Data JPA

Spring Data JPA is used to implement our Object-Relational Mapping (ORM).

It allows creating Data Access Objects (called Respositories in Spring terminology) simply by annotations and interfaces.


Spring Data Rest

Spring Data Rest is used to build hypermedia-driven REST web services on top of Spring Data repositories.

Woofer also uses the Projections feature.


Spring Cloud Netflix

Spring Cloud Netflix is a great contribution from Netflix, that embeds several features to build cloud applications.


Eureka server & client provides a very cheap and robust way of implementing services registration and discovery in a microservices architecture (more info).

Its use is quite straightforward as it only requires adding the right dependency to your pom.xml, and a basic annotation to your Sprint Boot application (either @EnableEurekaClient or @EnableEurekaServer).


Feign allows implementing declarative REST clients (i.e. through interfaces & annotations).

It is used in woofer-webfront to implement the woofer-backend REST client.



Ribbon provides client side load balancer.

Its use is quite straightforward as it only requires adding the right dependency to your pom.xml.

Spring Boot Actuator

Spring Boot Actuator provides a set of tools to monitor and manage your application.

Apart from default management endpoints, woofer-webfront and woofer-backend publish some business metrics to count active sessions, woofs and subscriptions.


Spring REST Docs

Spring REST Docs is a tool for generating part of REST API documentation.

It is used in woofer-backend project to generate the reference API documentation.


Spring Cloud Sleuth

Spring Cloud Sleuth is used for distributed tracing & logs correlation (see Logging - Code page for more details).