Check on debug launch configuration's `python` field prevents container debugging

[bwateratmsft]

The Docker extension resolves a Python debug configuration in order to support Python debugging. Included in that resolved debug configuration is the python field, with a value of just python3. This is because this is the command to use for launching Python in the container. However, validation of that field is done against the host, so if the host and container don't both have python3, debugging fails. We've tried changing it to python, which worked on Windows, but failed on Mac and Linux.

Is there a way to override this check to stop it from validating against the host when it should not be?

An additional strange thing we've noticed is that the error seems to only show up on Insiders. The code doesn't seem to be Insiders only so it's confusing why it would be doing this.

[bwateratmsft]

Downstream Docker extension bug: microsoft/vscode-containers#134

[karrtikr]

Can you provide us the full launch.json config for python that you're using? And in the case that it fails, please provide the logs:

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

XXX

[karrtikr]

Just to clarify, Python extension is running on the host, where "python" or "python3" does not exist, leading to the issue?

[bwateratmsft]

Here's the intermediate launch.json configuration--this is what the Docker extension takes as input and turns into a Python launch configuration. This is for a simple FastAPI project.

{
    "name": "Docker: Python - Fastapi",
    "type": "docker",
    "request": "launch",
    "preLaunchTask": "docker-run: debug",
    "python": {
        "pathMappings": [
            {
                "localRoot": "${workspaceFolder}",
                "remoteRoot": "/app"
            }
        ],
        "projectType": "fastapi"
    },
}

Here's the fully resolved debug configuration given to the Python extension's debug resolver:

{
    "name": "Docker: Python - Fastapi",
    "type": "python",
    "request": "launch",
    "preLaunchTask": "docker-run: debug",
    "python": "python3", // This is what is getting validated against the host improperly
    "__configurationTarget": 6,
    "pathMappings": [
        {
            "localRoot": "${workspaceFolder}",
            "remoteRoot": "/app"
        }
    ],
    "justMyCode": true,
    "django": false,
    "fastapi": true,
    "jinja": false,
    "dockerOptions": {
        "containerName": "fastapi-dev",
        "dockerServerReadyAction": {
            "containerName": "fastapi-dev",
            "pattern": "Uvicorn running on (https?://\\S+|[0-9]+)",
            "uriFormat": "%s://localhost:%s"
        }
    },
    "debugLauncherPath": "d:\\vscode-docker\\resources\\python\\launcher.py",
    "debugAdapterHost": "localhost",
    "console": "integratedTerminal",
    "internalConsoleOptions": "openOnSessionStart",
    "module": "uvicorn",
    "redirectOutput": true,
    "args": [
        "main:app",
        "--host",
        "0.0.0.0",
        "--port",
        "8000",
        "docker",
        "fastapi-dev"
    ],
    "cwd": ".",
    "debugAdapterPython": "${command:python.interpreterPath}",
    "debugLauncherPython": "${command:python.interpreterPath}"
}

This debug configuration will launch debugging against a container that is idling.

Just to clarify, Python extension is running on the host, where "python" or "python3" does not exist, leading to the issue?

Yes, the Python extension is running on the host, a Windows machine. Running python opens the Python 3 interpreter, but running python3 opens a Windows Store page to install Python as an app. As far as I know, this is a new behavior on Windows and I think it is why this problem only appeared now.

[bwateratmsft]

Here is the output from the Python output log with log level set to trace:

2024-02-07 09:32:41.405 [debug] Found cached env for C:\Python312\python.exe
2024-02-07 09:32:43.072 [debug] No cached env found for python3
2024-02-07 09:32:43.073 [warning] Failed to check if python3 is an executable [Error: ENOENT: no such file or directory, lstat 'C:\Users\bw\AppData\Local\Programs\Microsoft VS Code\python3'] {
  errno: -4058,
  code: 'ENOENT',
  syscall: 'lstat',
  path: 'C:\\Users\\bw\\AppData\\Local\\Programs\\Microsoft VS Code\\python3'
}
2024-02-07 09:32:43.075 [debug] Failed to get file info for python3 [Error: ENOENT: no such file or directory, lstat 'C:\Users\bw\AppData\Local\Programs\Microsoft VS Code\python3'] {
  errno: -4058,
  code: 'ENOENT',
  syscall: 'lstat',
  path: 'C:\\Users\\bw\\AppData\\Local\\Programs\\Microsoft VS Code\\python3'
}
2024-02-07 09:32:43.076 [debug] Environment resolver resolved python3 for {"name":"","location":"","kind":"unknown","executable":{"filename":"python3","sysPrefix":"","ctime":-1,"mtime":-1},"display":"Python","version":{"major":-1,"minor":-1,"micro":-1,"release":{"level":"final","serial":-1}},"arch":1,"distro":{"org":""},"source":[],"id":"PYTHON3","detailedDisplayName":"Python"} to undefined
2024-02-07 09:32:43.076 [debug] Resolved python3 using downstream locator
2024-02-07 09:32:43.076 [debug] Found cached env for C:\Python312\python.exe
2024-02-07 09:32:43.086 [debug] Activation Commands received undefined for shell cmd, resource d:\Sandbox\FastAPI and interpreter C:\Python312\python.exe
2024-02-07 09:32:43.090 [debug] No cached env found for python3
2024-02-07 09:32:43.091 [warning] Failed to check if python3 is an executable [Error: ENOENT: no such file or directory, lstat 'C:\Users\bw\AppData\Local\Programs\Microsoft VS Code\python3'] {
  errno: -4058,
  code: 'ENOENT',
  syscall: 'lstat',
  path: 'C:\\Users\\bw\\AppData\\Local\\Programs\\Microsoft VS Code\\python3'
}
2024-02-07 09:32:43.094 [debug] Failed to get file info for python3 [Error: ENOENT: no such file or directory, lstat 'C:\Users\bw\AppData\Local\Programs\Microsoft VS Code\python3'] {
  errno: -4058,
  code: 'ENOENT',
  syscall: 'lstat',
  path: 'C:\\Users\\bw\\AppData\\Local\\Programs\\Microsoft VS Code\\python3'
}
2024-02-07 09:32:43.095 [debug] Environment resolver resolved python3 for {"name":"","location":"","kind":"unknown","executable":{"filename":"python3","sysPrefix":"","ctime":-1,"mtime":-1},"display":"Python","version":{"major":-1,"minor":-1,"micro":-1,"release":{"level":"final","serial":-1}},"arch":1,"distro":{"org":""},"source":[],"id":"PYTHON3","detailedDisplayName":"Python"} to undefined
2024-02-07 09:32:43.095 [debug] Resolved python3 using downstream locator
2024-02-07 09:32:43.097 [error] Invalid Python Path 'python3'
2024-02-07 09:32:44.815 [debug] Clearing context for python dependencies not installed: ms-python.python.Python
2024-02-07 09:32:44.816 [debug] Found cached env for C:\Python312\python.exe

[karrtikr]

Thanks for that.

We do the validation yes, but I think this question is better suited for debugpy. We assume that the "python" specified contains a valid python binary in the host, but seems like that depends on the way launch config is specified?

If so, is there a way we can detect that, and thereby not do host validation in that case?

[bwateratmsft]

It seems like it has started occurring in non-Insiders builds as well now.

[bwateratmsft]

Thanks for that.

We do the validation yes, but I think this question is better suited for debugpy. We assume that the "python" specified contains a valid python binary in the host, but seems like that depends on the way launch config is specified?

If so, is there a way we can detect that, and thereby not do host validation in that case?

Perhaps if a custom debugLauncherPath is specified, the check should be skipped? Or a new flag could be added to override the check?

[karrtikr]

I think that could work, we should probably avoid adding a new flag though, unless absolutely needed.