Running a python program in debug mode

[ghost]

Can we use poethepoet to launch a python program in debug mode? I am trying to use it with VSCode debugger with following launch config.

{
    "name": "Python: Flask",
    "type": "python",
    "request": "launch",
    "module": "poethepoet",
    "args": ["start"],
    "justMyCode": true,
    "jinja": true
}

My task definition

[tool.poe.tasks]
start = { cmd = "python -m apps", help = "Start dev server (press F5 on VSCode)" }

It seems like poethepoet is running in debug mode, but the flask server isn't. I can debug my flask app without poethepoet using flask launch config provided by VSCode, but the can't debug it with poethepoet and take advantage of envfile feature built into it.

[nat-n]

That's an interesting question. I'm not really familiar with how the vscode debug mode works exactly, though I imagine that at least part of the problem is that the poethepoet process that you're attaching to is different than the python subprocess created to execute the apps module in this case.

In general poe runs tasks in subprocesses for a variety of reasons. The one exception to this rule is if you set use_exec = true on the cmd task as per the docs then it'll reuse the existing process.

I'm not sure if that'll help since although the task will run as the same process it's still a different python runtime. If that doesn't work then maybe there's some way to define the task to run the child process as the debug target, though I wouldn't know exactly how.

Let me know if you work it out!

[monim67]

I tested it with use_exec = true, doesn't work. Now I also think I need to define the task such that the python subprocess can connect to debugger. Don't know how yet.

[monim67]

Today I tested the same thing on Python 3.10 where it works just fine, but it doesn't work in 3.9. Is this a python related issue?

I was mistaken, it is not dependent on python version, rather depends on poethepoet version. The debugging only works in v0.16.1, doesn't work on the earlier or later version (v0.16.2). I wonder why it only works only on that version. Any idea?

Finally figured it out, if poethepoet executes the command the debugger works, if it executes the command with poetry run prefix the debugger doesn't work (don't know why). VSCode debugger activates poetry virtual environment by running the virtualenv activate script, so POETRY_ACTIVE environment variable is not set, so poethepoet executes the command with poetry run prefix, and thus the debugger doesn't work (doesn't stop at breakpoints).

The solution I came up with is very simple, just add the environment variable to vscode launch config (launch.json)

{
    "name": "Python: Flask",
    "type": "python",
    "request": "launch",
    "module": "poethepoet",
    "args": ["start"],
    "justMyCode": true,
    "jinja": true,
    "env": {
      "POETRY_ACTIVE": "1"
    }
}

[nat-n]

Thanks for reporting back on the solution!

I guess that makes sense, that using poetry run gets in the way, because then it is actually poetry running your task. My guess is that the debugger gets lost because it's probably a different python binary that runs poetry.

Regarding the versions.0.16.1 made some changes to how tasks are executed so poetry run is almost never used so that would explain the difference. Unfortunately I rolled back those changes in 0.16.2 because it caused issues on windows that I haven't gotten to the bottom of yet.