Debug port sometimes ignored

[danielniccoli]

I work with a multi-root workspace with one Azure Functions projects (mp_frontend) and one Azure Durable Functions project (mp_backend). I start both azure function hosts manually with the > Run Task palette command, instead of using F5. To run them concurrently, in project mp_backend I changed the ports of the http listener and debug server from the default 7071 to 7072, and the default 9091 to 9092 respectively. This mostly works.

However, from time to time the debug task of project mp_backend fails to start with error RuntimeError: Can't listen for client connections: [WinError 10048] Only one usage of each socket address (protocol/network address/port) is normally permitted. Whenever this happens, I triple-check that the ports 7072 and 9092 are not in use and I can confirm that they are not in use.

The error seems to be caused during the language worker startup and I assume that the Azure Functions extensions has troubles picking up the remote debug listen port (which is set to 9092 for project mp_backend) and so the language worker is trying to start on 9091, which is already used by the other project mp_frontend.

Task logs

*  Executing task in folder mp_backend: .venv\Scripts\python -m pip install -r requirements.txt 

Requirement already satisfied: azure-functions in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from -r requirements.txt (line 5)) (1.15.0)
Requirement already satisfied: azure-functions-durable in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from -r requirements.txt (line 6)) (1.2.4)
Requirement already satisfied: httpx in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from -r requirements.txt (line 7)) (0.24.1)
Requirement already satisfied: pydantic[email] in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from -r requirements.txt (line 8)) (2.1.1)
Requirement already satisfied: azure-identity in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from -r requirements.txt (line 9)) (1.14.0)
Requirement already satisfied: msgraph-sdk in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from -r requirements.txt (line 10)) (1.0.0a14)
Requirement already satisfied: aiohttp>=3.6.2 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from azure-functions-durable->-r requirements.txt (line 6)) (3.8.5)
Requirement already satisfied: requests==2.* in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from azure-functions-durable->-r requirements.txt (line 6)) (2.31.0)
Requirement already satisfied: python-dateutil>=2.8.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from azure-functions-durable->-r requirements.txt (line 6)) (2.8.2)
Requirement already satisfied: furl>=2.1.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from azure-functions-durable->-r requirements.txt (line 6)) (2.1.3)
Requirement already satisfied: charset-normalizer<4,>=2 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from requests==2.*->azure-functions-durable->-r requirements.txt (line 6)) (3.2.0)
Requirement already satisfied: idna<4,>=2.5 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from requests==2.*->azure-functions-durable->-r requirements.txt (line 6)) (3.4)
Requirement already satisfied: urllib3<3,>=1.21.1 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from requests==2.*->azure-functions-durable->-r requirements.txt (line 6)) (2.0.4)
Requirement already satisfied: certifi>=2017.4.17 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from requests==2.*->azure-functions-durable->-r requirements.txt (line 6)) (2023.7.22)
Requirement already satisfied: httpcore<0.18.0,>=0.15.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from httpx->-r requirements.txt (line 7)) (0.17.3)
Requirement already satisfied: sniffio in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages 
(from httpx->-r requirements.txt (line 7)) (1.3.0)
Requirement already satisfied: annotated-types>=0.4.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from pydantic[email]->-r requirements.txt (line 8)) (0.5.0)
Requirement already satisfied: pydantic-core==2.4.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from pydantic[email]->-r requirements.txt (line 8)) (2.4.0)
Requirement already satisfied: typing-extensions>=4.6.1 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from pydantic[email]->-r requirements.txt (line 8)) (4.7.1)
Requirement already satisfied: email-validator>=2.0.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from pydantic[email]->-r requirements.txt (line 8)) (2.0.0.post2)
Requirement already satisfied: azure-core<2.0.0,>=1.11.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from azure-identity->-r requirements.txt (line 9)) (1.29.2)
Requirement already satisfied: cryptography>=2.5 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from azure-identity->-r requirements.txt (line 9)) (41.0.3)
Requirement already satisfied: msal<2.0.0,>=1.20.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from azure-identity->-r requirements.txt (line 9)) (1.23.0)
Requirement already satisfied: msal-extensions<2.0.0,>=0.3.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from azure-identity->-r requirements.txt (line 9)) (1.0.0)
Requirement already satisfied: microsoft-kiota-abstractions<0.8,>=0.7 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from msgraph-sdk->-r requirements.txt (line 10)) (0.7.1)
Requirement already satisfied: microsoft-kiota-authentication-azure>=0.2 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from msgraph-sdk->-r requirements.txt (line 10)) (0.2.0)
Requirement already satisfied: microsoft-kiota-serialization-json<0.5,>=0.4 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from msgraph-sdk->-r requirements.txt (line 10)) (0.4.0)
Requirement already satisfied: microsoft-kiota-serialization-text>=0.2.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from msgraph-sdk->-r requirements.txt (line 10)) (0.2.1)
Requirement already satisfied: microsoft-kiota-http<0.6,>=0.5 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from msgraph-sdk->-r requirements.txt (line 10)) (0.5.0)
Requirement already satisfied: msgraph-core>=1.0.0a2 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from msgraph-sdk->-r requirements.txt (line 10)) (1.0.0a4)
Requirement already satisfied: attrs>=17.3.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from aiohttp>=3.6.2->azure-functions-durable->-r requirements.txt (line 6)) (23.1.0)
Requirement already satisfied: multidict<7.0,>=4.5 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from aiohttp>=3.6.2->azure-functions-durable->-r requirements.txt (line 6)) (6.0.4)
Requirement already satisfied: async-timeout<5.0,>=4.0.0a3 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from aiohttp>=3.6.2->azure-functions-durable->-r requirements.txt (line 6)) (4.0.2)
Requirement already satisfied: yarl<2.0,>=1.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from aiohttp>=3.6.2->azure-functions-durable->-r requirements.txt (line 6)) (1.9.2)
Requirement already satisfied: frozenlist>=1.1.1 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from aiohttp>=3.6.2->azure-functions-durable->-r requirements.txt (line 6)) (1.4.0)
Requirement already satisfied: aiosignal>=1.1.2 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from aiohttp>=3.6.2->azure-functions-durable->-r requirements.txt (line 6)) (1.3.1)
Requirement already satisfied: six>=1.11.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from azure-core<2.0.0,>=1.11.0->azure-identity->-r requirements.txt (line 9)) (1.16.0)
Requirement already satisfied: cffi>=1.12 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from cryptography>=2.5->azure-identity->-r requirements.txt (line 9)) (1.15.1)
Requirement already satisfied: dnspython>=2.0.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from email-validator>=2.0.0->pydantic[email]->-r requirements.txt (line 8)) (2.4.1)
Requirement already satisfied: orderedmultidict>=1.0.1 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from furl>=2.1.0->azure-functions-durable->-r requirements.txt (line 6)) (1.0.1)
Requirement already satisfied: h11<0.15,>=0.13 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from httpcore<0.18.0,>=0.15.0->httpx->-r requirements.txt (line 7)) (0.14.0)
Requirement already satisfied: anyio<5.0,>=3.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from httpcore<0.18.0,>=0.15.0->httpx->-r requirements.txt (line 7)) (3.7.1)
Requirement already satisfied: uritemplate>=4.1.1 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from microsoft-kiota-abstractions<0.8,>=0.7->msgraph-sdk->-r requirements.txt (line 10)) (4.1.1)
Requirement already satisfied: PyJWT[crypto]<3,>=1.0.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from msal<2.0.0,>=1.20.0->azure-identity->-r requirements.txt (line 9)) (2.8.0)
Requirement already satisfied: portalocker<3,>=1.6 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from msal-extensions<2.0.0,>=0.3.0->azure-identity->-r requirements.txt (line 9)) (2.7.0)
Requirement already satisfied: exceptiongroup in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from anyio<5.0,>=3.0->httpcore<0.18.0,>=0.15.0->httpx->-r requirements.txt (line 7)) (1.1.2)
Requirement already satisfied: pycparser in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from cffi>=1.12->cryptography>=2.5->azure-identity->-r requirements.txt (line 9)) (2.21)
Requirement already satisfied: h2<5,>=3 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from httpx->-r requirements.txt (line 7)) (4.1.0)
Requirement already satisfied: pywin32>=226 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from portalocker<3,>=1.6->msal-extensions<2.0.0,>=0.3.0->azure-identity->-r requirements.txt (line 9)) (306)
Requirement already satisfied: hyperframe<7,>=6.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from h2<5,>=3->httpx->-r requirements.txt (line 7)) (6.0.1)
Requirement already satisfied: hpack<5,>=4.0 in c:\users\niccodan\source\repos\multipass\mp_backend\.venv\lib\site-packages (from h2<5,>=3->httpx->-r requirements.txt (line 7)) (4.0.0)
*  Terminal will be reused by tasks, press any key to close it. 

*  Executing task in folder mp_backend: .venv\Scripts\activate ; func host start 

Found Python version 3.10.11 (py).

Azure Functions Core Tools
Core Tools Version:       4.0.5198 Commit hash: N/A  (64-bit)
Function Runtime Version: 4.21.1.20667

[2023-08-21T09:15:49.836Z] Language Worker Process exited. Pid=15036.
[2023-08-21T09:15:49.839Z] py exited with code 1 (0x1).     log.reraise_exception("{0}() failed:", func.__name__, level="info"),    raise RuntimeError(str(endpoints["error"])),RuntimeError: Can't listen for client connections: [WinError 10048] Only one usage of each socket address (protocol/network address/port) is normally permitted.
[2023-08-21T09:16:49.148Z] Starting worker process failed
[2023-08-21T09:16:49.150Z] Microsoft.Azure.WebJobs.Script.Grpc: The operation has timed out.
[2023-08-21T09:16:49.152Z] Failed to start language worker process for runtime: (null). workerId:61ccc680-7f3b-4af3-a289-89661b7cfac6
[2023-08-21T09:16:49.155Z] Removing errored webhost language worker channel for runtime: python workerId:61ccc680-7f3b-4af3-a289-89661b7cfac6  
[2023-08-21T09:16:49.156Z] Microsoft.Azure.WebJobs.Script.Grpc: The operation has timed out.
[2023-08-21T09:16:50.131Z] Traceback (most recent call last):
[2023-08-21T09:16:50.134Z]   File "C:\Users\niccodan\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 196, in _run_module_as_main   
[2023-08-21T09:16:50.136Z]     return _run_code(code, main_globals, None,
[2023-08-21T09:16:50.137Z]   File "C:\Users\niccodan\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 86, in _run_code
[2023-08-21T09:16:50.138Z]     exec(code, run_globals)
[2023-08-21T09:16:50.139Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy\__main__.py", line 39, in <module>
[2023-08-21T09:16:50.140Z]     cli.main()
[2023-08-21T09:16:50.141Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\cli.py", line 430, in main
[2023-08-21T09:16:50.142Z]     run()
[2023-08-21T09:16:50.142Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\cli.py", line 268, in run_file
[2023-08-21T09:16:50.144Z]     start_debugging(target)
[2023-08-21T09:16:50.145Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\cli.py", line 256, in start_debugging
[2023-08-21T09:16:50.146Z]     debugpy.listen(options.address)
[2023-08-21T09:16:50.147Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\public_api.py", line 31, in wrapper
[2023-08-21T09:16:50.149Z]     return wrapped(*args, **kwargs)
[2023-08-21T09:16:50.150Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\api.py", line 143, in debug
[2023-08-21T09:16:50.152Z]     log.reraise_exception("{0}() failed:", func.__name__, level="info")
[2023-08-21T09:16:50.153Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\api.py", line 141, in debug
[2023-08-21T09:16:50.154Z]     return func(address, settrace_kwargs, **kwargs)
[2023-08-21T09:16:50.156Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\api.py", line 262, in listen
[2023-08-21T09:16:50.157Z]     raise RuntimeError(str(endpoints["error"]))
[2023-08-21T09:16:50.159Z] RuntimeError: Can't listen for client connections: [WinError 10048] Only one usage of each socket address (protocol/network address/port) is normally permitted
[2023-08-21T09:16:51.092Z] Traceback (most recent call last):
[2023-08-21T09:16:51.094Z]   File "C:\Users\niccodan\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 196, in _run_module_as_main   
[2023-08-21T09:16:51.096Z]     return _run_code(code, main_globals, None,
[2023-08-21T09:16:51.097Z]   File "C:\Users\niccodan\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 86, in _run_code
[2023-08-21T09:16:51.098Z]     exec(code, run_globals)
[2023-08-21T09:16:51.099Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy\__main__.py", line 39, in <module>
[2023-08-21T09:16:51.100Z]     cli.main()
[2023-08-21T09:16:51.101Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\cli.py", line 430, in main
[2023-08-21T09:16:51.103Z]     run()
[2023-08-21T09:16:51.104Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\cli.py", line 268, in run_file
[2023-08-21T09:16:51.105Z]     start_debugging(target)
[2023-08-21T09:16:51.106Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\cli.py", line 256, in start_debugging
[2023-08-21T09:16:51.108Z]     debugpy.listen(options.address)
[2023-08-21T09:16:51.109Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\public_api.py", line 31, in wrapper
[2023-08-21T09:16:51.110Z]     return wrapped(*args, **kwargs)
[2023-08-21T09:16:51.111Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\api.py", line 143, in debug
[2023-08-21T09:16:51.112Z]     log.reraise_exception("{0}() failed:", func.__name__, level="info")
[2023-08-21T09:16:51.113Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\api.py", line 141, in debug
[2023-08-21T09:16:51.115Z]     return func(address, settrace_kwargs, **kwargs)
[2023-08-21T09:16:51.116Z]   File "c:\Users\niccodan\.vscode\extensions\ms-python.python-2023.14.0\pythonFiles\lib\python\debugpy/..\debugpy\server\api.py", line 262, in listen
[2023-08-21T09:16:51.117Z]     raise RuntimeError(str(endpoints["error"]))
[2023-08-21T09:16:51.119Z] RuntimeError: Can't listen for client connections: [WinError 10048] Only one usage of each socket address (protocol/network address/port) is normally permitted
[2023-08-21T09:16:51.130Z] Language Worker Process exited. Pid=25812.
[2023-08-21T09:16:51.132Z] py exited with code 1 (0x1).     log.reraise_exception("{0}() failed:", func.__name__, level="info"),    raise RuntimeError(str(endpoints["error"])),RuntimeError: Can't listen for client connections: [WinError 10048] Only one usage of each socket address (protocol/network address/port) is normally permitted.
[2023-08-21T09:16:51.141Z] Exceeded language worker restart retry count for runtime:python. Shutting down and proactively recycling the Functions Host to recover
[2023-08-21T09:17:50.200Z] Starting worker process failed
[2023-08-21T09:17:50.203Z] Microsoft.Azure.WebJobs.Script.Grpc: The operation has timed out.
[2023-08-21T09:17:50.204Z] Failed to start language worker process for runtime: (null). workerId:71e7699e-68b7-4e1f-99c3-365ba2dc801f
[2023-08-21T09:17:50.592Z] A host error has occurred during startup operation '968eb9f7-e015-42d4-aabd-f857725546c1'.
[2023-08-21T09:17:50.594Z] Microsoft.Azure.WebJobs.Script: Object reference not set to an instance of an object.
[2023-08-21T09:17:50.602Z] Failed to stop host instance 'ca441de7-d7af-4cee-9f94-a930b7fed513'.
[2023-08-21T09:17:50.604Z] Microsoft.Azure.WebJobs.Host: The host has not yet started.
Value cannot be null. (Parameter 'provider')
[2023-08-21T09:17:50.613Z] Host startup operation has been canceled

The tasks.json in both projects are identical and left unchanged.

PROJECT_ROOT\.vscode\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": []
    }
  ]
}

The launch.json in both projects are identical and left unchanged, except for mp_backend\.vscode\launch.json where I changed port from 9091 to 9092.

mp_backend\.vscode\tasks.json

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Attach to Python Functions",
      "type": "python",
      "request": "attach",
      "port": 9092,
      "preLaunchTask": "func: host start"
    }
  ]
}

The local.settings.json in both projects are identical, except for mp_backend\local.settings.json where I changed the LocalHttpPort from 7071 to 7072.

mp_backend\local.settings.json

{
  "IsEncrypted": false,
  "Values": {
  "FUNCTIONS_WORKER_RUNTIME": "python",
  "AzureWebJobsStorage": "UseDevelopmentStorage=true",
  "AzureWebJobsFeatureFlags": "EnableWorkerIndexing",
  "AZURE_TENANT_ID": "3817f61a-40c0-428b-8591-37b24bf6ceeb",
  "AZURE_CLIENT_ID": "da27fd11-a79b-4eb1-9d03-d92ccaa82fcb",
  "AZURE_CLIENT_SECRET": "UO98Q~iogInhqExbligFj8uEhu6k8bicHbqoBcz0"
  
  },
  "Host": {
  "LocalHttpPort": 7072
  }
}

[alexweininger]

Thank you for the detailed issue report. It's very odd that this happens inconsistently.

Can you provide the task logs for when it doesn't fail?

Does it still happen if you wait for the frontend task to finish completely before starting the backend task?

Also, from the task logs, the func host start command is failing. Does this reproduce without using tasks at all and instead running the func host start commands manually in each place? If so, the issue might be in Azure Functions Core Tools and not in the VS Code extension.

[danielniccoli]

Hi @alexweininger,

after more troubleshooting I finally found the reason why this happens. I was trying to change the port the Azure Functions Python Language Worker debug server listens to. As a workaround, @vrdmr suggested that the vscode-azurefunctions extension does some behind-the-scenes magic to pass the target port from launch.json to the language worker debug server listener.

The reason I had so many issues is that due to the facts that I use a multi-root environment together with the project-related launch.json files. And I cannot use F5 to to start both debuggers at the same time. Once the first debugger is launched, I must use the command palette to 1) manually launch the func host via Tasks: Run Task and 2) manually attach the debugger to the debug server. And not starting the debugging via F5, or the Debug: Start Debugging palette command does not trigger this extensions behind-the-scenes magic.

I'm still waiting for the language worker team to document how to explicitly change the listen port on the debug server, to skip the magic altogether. But may it be a good idea to do the same magic, too, when the task is run explicitly? I would open a feature request, if that makes sense.

[alexweininger]

Ok, that makes sense @danielniccoli. We can certainly make some changes to improve and fix the experience here. In the meantime I'm going to create a project that mimics the structure of your project and try to come up with some workarounds. I'll try my best to get back to you with my findings soon.

[alexweininger]

@danielniccoli

Specifying language worker debug port

not starting the debugging via F5, or the Debug: Start Debugging palette command does not trigger this extensions behind-the-scenes magic.

You're correct. The port property in the debug configuration (launch.json) is only respected when debugging (launching via F5 or the debug menu). When the task is run directly, this port property will not be used.

I'm still waiting for the language worker team to document how to explicitly change the listen port on the debug server, to skip the magic altogether.

You can pass arguments to the Python language worker via the languageWorkers__python__arguments environment variable. It's probably easiest to define it directly in the task like so:

"options": {
    "env": {
        "languageWorkers__python__arguments": "--port 9092"
    }
}

Specifying this should at least make the task always use the correct debug port.

Using the debug configurations

And I cannot use F5 to to start both debuggers at the same time.

I can attest that using F5 to start both debug configurations doesn't work. The first launches normally, however upon launching the second debug configuration, nothing runs and an error instantly appears: "connect ECONNREFUSED 127.0.0.1:9092".

The prelaunch task for the second debug configuration doesn't even launch. I think this is a VS Code bug that prevents the same task from being launched even though we're trying to launch them in separate workspace folders. The easiest workaround I found for this is to just modify the second prelaunch task by adding --port 7072 to the command property.

My modified launch.json (backend)

{
  "version": "2.0.0",
  "tasks": [
    {
      "type": "func",
      "label": "func: host start",
      "command": "host start --port 7072",
      "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": []
    }
  ]
}

This makes VS Code treat the tasks as unique and now I can launch both debug configurations using the debug menu at the same time without issues.

[alexweininger]

I've filed an issue on VS Code that once fixed should allow users to launch multiple debug configurations without having to create unique pre launch tasks.

microsoft/vscode#191949

[alexweininger]

@danielniccoli, a fix for microsoft/vscode#191949 has been released in the latest VS Code insiders bulid 1.83.0-insider.

This should allow you to launch both debug configurations at the same time without having to manually run any tasks. Please let me know if this works for you. I have it working locally, I'd be glad to help get it working for you.

[danielniccoli]

I don't use the insider and I trashed the multi-root repository, because it caused so many issues in so many different places. Multi-root support in VS Code and its extension is a buggy mess. So I won't be able to confirm and will close the issue. Many thanks for your time and contributions!