Debugging in VSCode

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In debug with the debug gem, we can use the debugger command for debugging with Ruby 3.1.

If you restart the server, you will actually catch the debugger. This isn't super useful when using things like a Procfile.

With debug, you can use outline <class> to see all methods on a command.

We can use a tool rdbg that comes along with the new debug Gem. We can use the command rdbg -c -- bin/rails s that will launch whatever the command is but first pause and attach the debugger to it.

We can start adding in flags and commands to build this up a bit. rdbg -n -c -- bin/rails s won't run the initial pause.

We can also tell is what frontend to open by default rdbg -n --open=vscode -c -- bin/rails s .

By default, it won't work by default since there is no awareness of the debugger in VSCode.

We can amend this by installing the VSCode rdbg Ruby Debugger plugin written by the same guy who added in the bulk of the 3.1 debug work.

Once installed, we can run the command again and VSCode will hook in.

If we want to fold this into our application, we can wire this in as a launch configuration.

Make a new launch config in VSCode:

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "rdbg",
      "name": "Attach with rdbg",
      "request": "attach"
    }
  ]
}
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Now from the VSCode terminal, we can run rdbg -n --open=vscode -c -- bin/rails s and then we can run the Attach with rdbg configuration.

Once this is done, we can now remove the debugger statement and use the debugger breakpoint from selecting in VSCode. You may need to restart and reattach.

From this point, we can also use the stepper as we normally would.

Now we want to adjust things to just work from the bin/dev command on Rails 7. For that, we would just adjust the Procfile.dev so that the web command is prefixed with the rdbg command.