Last updated: 6 Jul 2026

finder-frontend: 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": "finder-frontend.dev.gov.uk:12347",
      "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 finder-frontend (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)