I have a Python 3.11 Function App that runs locally. I'm developing on Windows 11, and VS Code, fwiw.

I have all of the Azure extensions; I have the Azure Tools extension pack, which includes the Functions extension, installed/enabled. It works great for other types of Function Apps and App Services we use.

func host start starts the application as expected. I am connected to a remote queue storage account -- I can drop messages onto the queue and see it get picked up by my locally-running app.

I'd love to be able to debug and step through the code when it processes a message. However, I have a breakpoint set right where I know code is getting executed, as well as other lines, and I never see them get hit. I know the debugger is not attached, because I don't see the debugger controls

So, I have the following launch.json:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Attach to Python Functions",
            "type": "debugpy",
            "request": "attach",
            "justMyCode": true,
            "connect": {
                "host": "localhost",
                "port": 7071
            },
            "preLaunchTask": "func: host start",
            "env": {
                "PYDEVD_DISABLE_FILE_VALIDATION": "1"
            }
        }
    ]
}

tasks.json:

{
    "version": "2.0.0",
    "tasks": [
        {
            "type": "func",
            "label": "func: host start",
            "command": "host start --port 7071 --enable-debugging",
            "problemMatcher": "$func-python-watch",
            "isBackground": true,
            "dependsOn": "pip install (functions)"
        },
        {
            "label": "pip install (functions)",
            "type": "shell",
            "osx": {
                "command": "${config:azureFunctions.pythonVenv}/bin/python -m pip install -r requirements.txt"
            },
            "windows": {
                "command": "${config:azureFunctions.pythonVenv}\\Scripts\\python -m pip install -r requirements.txt"
            },
            "linux": {
                "command": "${config:azureFunctions.pythonVenv}/bin/python -m pip install -r requirements.txt"
            },
            "problemMatcher": []
        }
    ]
}

My local.settings.json holds nothing exciting:

{
  "IsEncrypted": false,
  "Values": {
    "FUNCTIONS_WORKER_RUNTIME": "python",
    "AzureWebJobsStorage": "UseDevelopmentStorage=true"
  }
}

Here's a screenshot showing the app is running fine:

So what gives? Why, when pushing F5, the Function App spins up fine, but the debugger does not attach?

解决方案

To debug locally and hitting it with a break point, you have to use Start Debugging in Run as below:

Now add a break point and it will hit now, when you click on Start Debugging:

Even when I press F5 it is working with :

launch.json:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Attach to Python Functions",
            "type": "debugpy",
            "request": "attach",
            "connect": {
                "host": "localhost",
                "port": 9091
            },
            "preLaunchTask": "func: host start"
        }
    ]
}

tasks.json:

{
    "version": "2.0.0",
    "tasks": [
        {
            "type": "func",
            "label": "func: host start",
            "command": "host start",
            "problemMatcher": "$func-python-watch",
            "isBackground": true,
            "dependsOn": "pip install (functions)"
        },
        {
            "label": "pip install (functions)",
            "type": "shell",
            "osx": {
                "command": "${config:azureFunctions.pythonVenv}/bin/python -m pip install -r requirements.txt"
            },
            "windows": {
                "command": "${config:azureFunctions.pythonVenv}\\Scripts\\python -m pip install -r requirements.txt"
            },
            "linux": {
                "command": "${config:azureFunctions.pythonVenv}/bin/python -m pip install -r requirements.txt"
            },
            "problemMatcher": []
        }
    ]
}

Try installing the debugpy:

Firstly check if debugpy:

pip show debugpy

If not there install it:

pip install debugpy
pip show debugpy

Upgrade Azure Function Core Tools.

Alternatively, you can also check here:

For further information refer SO-Thread1 and SO-Thread2 and Microsoft-Document.