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To do so, the Java platform allows developer to attach a debugger to a running JVM.

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Passing the remote debugging JVM options 

The JVM you wish to attach the debugger to has to be started with a certain set of parameters for the remote debugging capability to be enabled.In particular, you should edit the startup script you use (either bin/yarn-session.sh for YARN or bin/flink-daemon.sh for the standalone scheduler) adding the following parameters to the java command:

-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005

The command specifies to open the the 5005 port  port (make sure your firewall poses no problem) and to suspend the process until a debugger is attached to the process. If you wish to allow remote debugging without having to attach a debugger before startup, simply set suspend=n.

Passing the JVM options via env.java.opts

In order to pass the remote debugging options to the JVM you can use Flink's env.java.opts configuration parameter. Simply set in the flink-conf.yaml the following line before starting your Flink cluster.

env.java.opts: "-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005"

Passing the JVM options as a dynamic property

When starting Flink in YARN mode via the bin/yarn-session.sh script you can also provide the JVM options via a dynamic property. Simply add the following option to your yarn-session.sh command.

bin/yarn-session.sh -Denv.java.opts="-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005"

Editing the start-up scripts

Alternatively, you can edit the startup scripts bin/yarn-session.sh (for YARN) or bin/flink-daemon.sh (for standalone cluster) to include the JVM options.

Attach a remote debugger with IntelliJ IDEA

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Attach a remote debugger with Eclipse

Similarly to IntelliJ, it is possible to debug a running Flink instance on a remote machine from Eclipse

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These are the required steps:

  1. Go to the menu 'Run' -> 'Debug configurations...'
  2. Create a new 'Remote Java Application'
  3. In the 'Connect' tab choose:
    1. the project to debug
    2. Connection type 'Standard (Socket Attach)'
    3. Connection properties, host (i.e. target hostname or IP address) and port (same port specified before, i.e.  5005)
  4. (Optional) If you have installed Scala IDE you could see the error 'Multiple launchers available'. Just click on 'Select one' and choose the proper debugger (e.g. Eclipse JDT Launcher)