VSCode-如何使用启动配置调试启动其自己的调试器的Node程序？

Question

(Note : my specific use case may seem complex, but the underlying idea is not!)

I have a Gulp script that starts a Docker container, which itself contains and starts another Gulp script that use Nodemon to start a final Node script in debug mode! The Nodemon Gulp script ran inside the Docker container looks something like this :

nodemon({
    "script": `start.js`,
    "nodeArgs": [`--debug=0.0.0.0:5858`, "-nolazy"],
    "ext": "js",
    "restartable": true
});

I'd like to be able to press [F5] in Visual Studio Code, have the final script started and have VSCode's debugger attached to it!

What does work :

If I start the first Gulp script manually, in a terminal, the Docker container is started, the other embedded Gulp script with Nodemon is executed and the final script is started. I can then press [F5] in VSCode to start an attach launch configuration and I'm able to debug! The port 5858 is exposed by Docker and everything runs fine.

What I want :

I want to be able to skip the manual launching of the script in a terminal. I want a VSCode launch configuration that does everything by itself => launch the script in VSCode's integrated terminal and attach a debugger to the debug process started by the script itself.

I tried :

1. An "request": "attach" launch configuration with a preLaunchTask task. That task is launching the first Gulp script. The problem with this approach is that the preLaunchTask task never ends : it starts the first script in the terminal (The task has a : " "_runner": "terminal" ") but in the end the final script is listening and doesn't exit (it's actually listening for requests)... This seems to prevent the VSCode debugger to start because the preLaunchTask task never exit.

2. A "request": "launch" launch configuration that starts the first script. But here, even if it looks like it is going to work (the orange debugging bar appears), the debugging never actually work. If I understand correctly, this is because a launch launch configuration starts a Node debugger by itself (on the specified port) and therefore the debugger starts by Nodemon, inside the Docker container, will never be listened to.

In other words : I simply want to hit [F5] so a script is launched in the integrated terminal, without debugger, and then VSCode will attach a debugger to the resulting 127.0.0.1:5858 debug process, wathever how this process is actually started.

UPDATE : I also had a suggestion on Github about trying to use a compound launch configuration, but it also doesn't work: https://github.com/Microsoft/vscode/issues/36685

Answer 1

Your first try, an attach config with a preLaunchTask is correct. You probably just need one adjustment. By default, vscode will be waiting for the task to terminate, so you need to tell it that the task will run in the background, by adding "isBackground": true . Then you need to tell it which patterns to watch for in the task's output to know when the task is complete. This bit is a little annoying, because you have to do this with a problemMatcher, but this task should not contribute problems, so you need to give it a regex that won't match anything. eg:

"problemMatcher": {
    "pattern": {
        "regexp": "__________"
    },
    "background": {
        "activeOnStart": false,
        "beginsPattern": "Some pattern when the debugging process is about to start",
        "endsPattern": "Ready for attach"
    }
}

The task runner is watching the program output to match endsPattern - when some output matches, then it will know the program is ready for the debugger to attach. If your script isn't producing any output, you should add some console.log after invoking nodemon .

Usually the problemMatcher is for matching problems output by the build task, and the regex can match the filename, line, and error message. But here we are just using it for the "background" patterns, so we give it a dummy regex. Here's a thread describing this workaround and how it could be easier in the future by moving the "background" patterns out of the patternMatcher: https://github.com/Microsoft/vscode/issues/6209#issuecomment-289411630

And here is the documentation on watching tasks, for more details: https://code.visualstudio.com/docs/editor/tasks#_background-watching-tasks