how to debug spring application with gradle

Question

I am working on spring app and need to step through a controller method to see how it works. I am working in eclipse and building my app with gradle bootRun command.

How to run it in debug mode?

i tried gradle bootRun --debug but it's just debug log, not debug mode

i tried gradle help --task bootRun -- this gives me info about task there i saw --debug-jvm option but when i run gradle bootRun --debug-jvm application doesn't start

Solution 1

After you run gradle bootRun --debug-jvm the application is suspended until you connect your debugger to the port it is listening on (port 5005).

Solution 2

As a response to dankdirkd's answer above: (compare)

gradle bootRun --debug-jvm

will make the gradle build run in debug mode. That probably is not what you want. What you want to achieve is that the springBoot task starts your application in debug mode.

The spring boot task extends the gradle JavaExec task. You can configure the bootRun task in your build.gradle file to add a debug configuration like this:

bootRun {
  jvmArgs=["-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=32323"]
}

For the build.gradle.kts this would look like this (with suspend mode disabled):

tasks {
    val bootRun by getting(BootRun::class) {
        jvmArgs=listOf("-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=32323")
    }
}

If your server is within a cloud and you want to debug from local machine, you need to make sure that it allows connections from outside. Use below configuration in that case

tasks {
val bootRun by getting(BootRun::class) {
    jvmArgs=listOf("-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=0.0.0.0:32323")
    }
}

Note that the address is now 0.0.0.0:port instead of just port

Solution 3

For build.gradle.kts file you can also simply use below:

tasks.withType<BootRun> {
    jvmArgs = listOf("-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=0.0.0.0:32323")
}

Solution 4

I personally prefer going under Gradle tasks and right-clicking on the bootRun. This is useful in the IDE compared to the terminal.

View more solutions

Comments

[Pete_ch]

having an issue running gradle bootRun --debug-jvm. hangs at Building 96% > :<project>:bootRun

[Neal.Shan]

this is the right answer, suspended means you need to click your remote debug button to connect to listener and then app start :P

[hariharan kumar]

By default, the debug port is 5005. How to start from a custom port say 5006?

[AlikElzin-kilaka]

Also, how to start without suspend?

[Jazzepi]

I don't believe that --debug-jvm debugs the main gradle process. The bootRun process is a subclass of JavaExec which starts a child process in debug mode when receiving the --debug-jvm flag. docs.gradle.org/current/dsl/…

[Lucas Basquerotto]

@hariharankumar I haven't tested with bootRun specifically, but the BootRun task extends JavaExec (github.com/spring-projects/spring-boot/blob/master/…), and I made it work with JavaExec passing jvmArgs to the task, so you could apply a similar logic: stackoverflow.com/a/53946140/4850646

[Nick Wills]

Thanks. This indeed can allow developer to leaverage on breakpoint and trace thru codes. However, is there a way to combine both steps (run apps and attach debugger) Ina single execution of command or a button click. Cos Everytime when we make java code change, we have to stop the above process. Then execute these 2 steps manually. Seem like a chores to me.

[Nick Wills]

But how do u use Gradle tasks to run an application in debug mode? I also don't like the idea of using temrinal

[Nick Wills]

So i just add bootRun { jvmArgs=["-agentlib:jdwp=transport=dt_socket,server=y,suspen‌​d=y,address=32323"] } into the build.gradle. And that's it?