SivaLabs

We all know how to run SpringBoot application in debug mode from our favorite IDEs(Eclipse/IntellijIDEA etc) and debug the code. Recently I had to debug a SpringBoot application which is running on a remote server.

There is already lot of information on the Internet on how to remote debug java applications, but some approaches didn’t work for me. So, here I would like to share my findings.

If application is running on localhost

Suppose you are running your application on localhost only and remote debug from your IDE.

$ export JAVA_OPTS='-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8787'
$ java $JAVA_OPTS -jar myapp.jar

You might have seen debug options specified as “-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8787”. But in the newer versions of Java the preferred approach is “-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8787”

Now from Intellij IDEA you can remote debug the application by creating remote debug configuration by Run -> Edit Configurations... -> Add New Configuration (Command + N) -> Enter Host and Port values

After creating debug configuration click on Debug, and you should see the following message:

Connected to the target VM, address: 'localhost:8787', transport: 'socket'

If application is running on remote host

Suppose you need to run the application on a remote host and debug from your localhost.

On Remote Server:

$ export JAVA_OPTS='-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8787'
$ java $JAVA_OPTS -jar myapp.jar

I followed the same approach as mentioned above and in debug configuration I gave the remote server’s IP address instead of localhost. But, when I click on Debug I got the following error:

unable to open debugger port (198.xxx.xxx.xx:8787): java.net.ConnectException "Connection refused"

After a bit of googling I finally resolved the issue by starting the application on remote server as follows:

$ export JAVA_OPTS='-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=0.0.0.0:8787'
$ java $JAVA_OPTS -jar myapp.jar

Note we gave the address as address=0.0.0.0:8787 instead of address=8787.

With this I am able to remote debug the application in the same way I did when I run it on localhost.

By the way, we can also run our SpringBoot application in debug mode as follows without creating jar file:

mvn spring-boot:run -Dspring-boot.run.jvmArguments="-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8787"

Happy debugging :-)