Debugging Spring Rest endpoint from your IDE

Today I had trouble debugging a Rest endpoint in a Spring Boot application.

 

The Problem

To start the debugger from the IDE, I simply right-clicked the main method and ran the debugger:

Despite getting all the logs for the scheduled tasks and no error messages, I couldn’t hit the breakpoint in my endpoint method.

 

Realisation

Eventually I noticed that Tomcat wasn’t logging its initialisation. Therefore, I was missing this line from the logged messages:

INFO 4447 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8050 (http)

 

Solution

The plugin

It took just a few minutes googling to come across Spring Boot Maven Plugin.

 

In pom.xml

Add the plugin:

<plugin>
    <groupid>org.springframework.boot</groupid>
    <artifactid>spring-boot-maven-plugin</artifactid>
    <configuration>
        <jvmarguments>
            -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005
        </jvmarguments>
    </configuration>
</plugin>

In the console

To prepare the application for debugging, run:

mvn spring-boot:run

The app at this stage will halt execution until the debugger is attached to it:

[INFO] Attaching agents: []
Listening for transport dt_socket at address: 5005

In the IDE

Add a new remote debugger making sure of using the same port the plugin broadcasts on.

That is it. Now the endpoints are running on debug mode.

App version number in Java code with Maven and Spring Boot

This is an easy way to access the version number of your application version in Java using Spring Boot.

Environment

• Maven 3.3.3
• Spring Boot v1.3.1.RELEASE
• Java 1.7.0_80

Steps

• In you application.properties add a placeholder application.version.number that will be passed in from Maven.

version.number=@application.version.number@

• Added the placeholder as new property in you pom.xml

<application.version.number>${version}</application.version.number>

• Inject the new config into the Spring bean you need

@Value("${version.number}")
private String versionNumber;