Spring Boot Devtools by Example

Question

According to the Spring Boot Devtools docs, devtools won't run in "production mode"; that is, if you execute your Spring Boot app with java -jar .., then it won't use devtools' built-in JVM magic. However, the Spring Boot starter docs only show you one way of running your Spring Boot application...via java -jar....

So first I'm wondering: How do I run my Spring Boot app in non-production mode? I know you can run your app with Spring Boot CLI (e.g. spring run), but is that the only way?

Also, the same devtools docs mention you can explicitly remove the devtools jar from your production binary by using some excludeDevtools option, but they never explain where/how to use this. Any examples/ideas here?

Answer 1

1) One example of running a Spring Boot app in non-production mode (i.e. not from the JAR) is from an IDE (most specifically Eclipse or IntelliJ), where you can launch the application from the main method, or using the Spring Boot launch support. This is the most practical use of Dev Tools as it allows to continuously watch the changes in your application without restarting.

2) excludeDevTools is an option of the Spring Boot Maven Plugin http://docs.spring.io/spring-boot/docs/current-SNAPSHOT/maven-plugin/repackage-mojo.html or the Gradle plugin - see http://docs.spring.io/spring-boot/docs/current/reference/html/build-tool-plugins-gradle-plugin.html#build-tool-plugins-gradle-repackage-configuration.

So in your case it would be bootRepackage { mainClass = 'demo.Application' excludeDevtools = true }