Last updated: 8 Jul 2026

feedback: Debugging in VS Code

If you want to debug within VS Code, you'll need the VSCode rdbg Ruby Debugger extension, and once that's installed, create a configuration file for it at .vscode/launch.json containing the following values

{
  // Use IntelliSense to learn about possible attributes.
  // Hover to view descriptions of existing attributes.
  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    {
      "type": "rdbg",
      "name": "Attach with rdbg",
      "request": "attach",
      "debugPort": "feedback.dev.gov.uk:12348",
      "localfsMap": "/:${userHome}"
    }
  ]
}

Then run govuk-docker-up, and use the Run and Debug tab and press the play button next to "Attach with rdbg", at which point you'll be able to set breakpoints in your code.

Note: the magic number in the debugPort setting should match the equivalent one in govuk-docker for feedback (by default the debug port creates itself at 12345, but to avoid clashes if running more than one app, we redirect that port to different numbers on the host)