A good practice, when building a spring application is to have few profiles. Usually everyone adds three common ones: dev, test, prod. Therefore each time you run you application with gradle using bootRun task you need to remeber to pass value for system property spring.profiles.active. However configuring the task to be run with predefined profile could be dangerous. Imagine what could happen if you service is run with profile dev on production. My idea is to create a separate task, that would initialize all properties for developing purposes.

Preconditions

The code below requires you to apply plugin spring-boot to your build process.

Creating a task in gradle that extends another

Creating a task in gradle that extends another one is terrbile simple. The following line would create newTask extending ExtendedClass:

  task newTask(type: ExtendedClass)

In our case we would like to extend task org.springframework.boot.gradle.run.BootRunTask that is part of the spring-boot-gradle-plugin. This task runs the project with support for auto-detecting main class and reloading static resources. Lets choose bootRunDev name for out new task. Therefore the line to be placed in in your build.gradle shoud be:

  task bootRunDev(type: org.springframework.boot.gradle.run.BootRunTask)

The attemp to use this command to start application results in error:

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':execute'.
> No main class specified

Executing building process before task execution

To be able to find a main class, we need to build an application beforehand. Therefore we should add dependency to build task. This changes our task definition into:

  task bootRunDev(type: org.springframework.boot.gradle.run.BootRunTask, dependsOn: 'build')

Configuring a task to set up main class name and classpath before execution

In our new task configuration we need to add additional behaviour before task is executed. We add this by calling method doFirst with following closure:

{
		main = project.mainClassName
		classpath = sourceSets.main.runtimeClasspath
}

The project property mainClassName was set up by one of the bootRun dependency the task findMainClass, that is a part of the spring-boot-gradle-plugin as well. If you take a look at lists of tasks executed before bootRun, this one will be there. In order to make the new task easy findable, you can assign it to the same predfined group as bootRun. To do his just add following line to the task configuration: group = 'Application'

Configuring a task to set up system properties before execution

The last thing, that is missing is seting up the active spring profiles. We achive it by adding systemProperty "spring.profiles.active", "dev" to closure passed to doFirst method. The final code generting new task should be like this:

task bootRunDev(type: org.springframework.boot.gradle.run.BootRunTask, dependsOn: 'build') {
	group = 'Application'
	doFirst() {
		main = project.mainClassName
		classpath = sourceSets.main.runtimeClasspath
		systemProperty 'spring.profiles.active', 'dev'
	}
}

Now when you command ./gradlew bootRunDev in your projects directory, your spring-boot application will be run with dev profile activated.

Source code of real life solution can be found here