Wiring up Spring Boot DevTools

The spring-boot-dev-tools module allows you to automatically restart your application whenever you make changes. It works by detecting changes to files on the classpath. To add devtools to a project just add the dependency to your build.gradle as shown below:

configurations {
    developmentOnly
    runtimeClasspath {
        extendsFrom developmentOnly
    }
}
dependencies {
    developmentOnly("org.springframework.boot:spring-boot-devtools")
}

If you are using Intellij IDE you can trigger a restart by building the project. When working with an IDE that continually compiles changes you can use a trigger file and restarts will only occur when that file changes.

spring.devtools.restart.trigger-file=.reloadTriggerFile

Gradle’s continuous build allows you to use devtools when you are not working with and IDE. Since it continuously runs a task you can use it to continuously build the project.

In the first terminal window, navigate to the project and run:

gradle build --continuous

In the second, navigate to the project and run the app

gradle bootRun

With this gradle will behave as if you have run gradle build when you save changes to files, this will in-turn trigger a restart.

You can find an example on github.