Debugging a CorDapp

There are several ways to debug your CorDapp.

Using a MockNetwork

You can attach the IntelliJ IDEA debugger to a MockNetwork to debug your CorDapp:

  • Define your flow tests as per API: Testing

    • In your MockNetwork, ensure that threadPerNode is set to false
  • Set your breakpoints

  • Run the flow tests using the debugger. When the tests hit a breakpoint, execution will pause

Using the node driver

You can also attach the IntelliJ IDEA debugger to nodes running via the node driver to debug your CorDapp.

With the nodes in-process

  1. Define a network using the node driver as per Integration testing

    • In your DriverParameters, ensure that startNodesInProcess is set to true
  2. Run the driver using the debugger

  3. Set your breakpoints

  4. Interact with your nodes. When execution hits a breakpoint, execution will pause

    • The nodes’ webservers always run in a separate process, and cannot be attached to by the debugger

With remote debugging

  1. Define a network using the node driver as per Integration testing

    • In your DriverParameters, ensure that startNodesInProcess is set to false and isDebug is set to true
  2. Run the driver. The remote debug ports for each node will be automatically generated and printed to the terminal. For example:

[INFO ] 11:39:55,471 [driver-pool-thread-0] (DriverDSLImpl.kt:814) internal.DriverDSLImpl.startOutOfProcessNode -
    Starting out-of-process Node PartyA, debug port is 5008, jolokia monitoring port is not enabled {}
  1. Attach the debugger to the node of interest on its debug port:

    • In IntelliJ IDEA, create a new run/debug configuration of type Remote
    • Set the run/debug configuration’s Port to the debug port
    • Start the run/debug configuration in debug mode
  2. Set your breakpoints

  3. Interact with your node. When execution hits a breakpoint, execution will pause

    • The nodes’ webservers always run in a separate process, and cannot be attached to by the debugger