Fail to debug Python project on Linux

[v-mengwe]

OS: Linux
Build Version: 20200608.5

Repro Steps:

1. Open a Python project(Django/Flask) in VS Code.
2. F1 -> Docker: Add Docker Files to Workspace -> Python ->include docker compose files.
3. F5.

Expect:
Debug Python project successfully without any error.

Actual:
Fail to debug Python project.

More Info:
This issue does not reproduce on Windows and Mac.

[haniamr]

@v-mengwe I'm unable to repro this exact issue, however, for Flask apps I do get the same error as in this issue: #2048.

What app are you using here and can you share the output from "Docker" and "Python" terminals?
Also is that due to modifying any networking settings for the container?

[v-mengwe]

@haniamr Thanks for your sharing.
Verified on the latest build 20200609.5, this issue still reproduces. I am using the following apps:

• Flask: https://github.com/Microsoft/python-sample-vscode-flask-tutorial/tree/tutorial
• Django: https://github.com/Microsoft/python-sample-vscode-django-tutorial/tree/tutorial

Output logs:
"Docker" terminals:

Executing task: docker-build <

docker build --rm --pull -f "/home/serene/Downloads/python-sample-vscode-django-tutorial-tutorial/Dockerfile" --label "com.microsoft.created-by=visual-studio-code" -t "pythonsamplevscodedjangotutorialtutorial:latest" "/home/serene/Downloads/python-sample-vscode-django-tutorial-tutorial" <

Sending build context to Docker daemon 175.1kB
Step 1/12 : FROM python:3.8-slim-buster
3.8-slim-buster: Pulling from library/python
8559a31e96f4: Pulling fs layer
62e60f3ef11e: Pulling fs layer
93c8ae153782: Pulling fs layer
ea222f757df7: Pulling fs layer
e97d3933bbbe: Pulling fs layer
ea222f757df7: Waiting
e97d3933bbbe: Waiting
62e60f3ef11e: Verifying Checksum
62e60f3ef11e: Download complete
ea222f757df7: Verifying Checksum
ea222f757df7: Download complete
e97d3933bbbe: Verifying Checksum
e97d3933bbbe: Download complete
8559a31e96f4: Verifying Checksum
8559a31e96f4: Download complete
8559a31e96f4: Pull complete
62e60f3ef11e: Pull complete
93c8ae153782: Verifying Checksum
93c8ae153782: Download complete
93c8ae153782: Pull complete
ea222f757df7: Pull complete
e97d3933bbbe: Pull complete
Digest: sha256:938fd520a888e9dbac3de374b8ba495cc50fe96440030264a40f733052001895
Status: Downloaded newer image for python:3.8-slim-buster
---> 9d84edf35a0a
Step 2/12 : EXPOSE 8000
---> Running in 2b1d3b6caf70
Removing intermediate container 2b1d3b6caf70
---> a8a61234f693
Step 3/12 : ENV PYTHONDONTWRITEBYTECODE 1
---> Running in 2ae9ed978177
Removing intermediate container 2ae9ed978177
---> 7c7c72854e98
Step 4/12 : ENV PYTHONUNBUFFERED 1
---> Running in 63a8d5c666aa
Removing intermediate container 63a8d5c666aa
---> c59843e7a59e
Step 5/12 : ADD requirements.txt .
---> b33a94036121
Step 6/12 : RUN python -m pip install -r requirements.txt
---> Running in b98bfa542add
Collecting django==3.0.3
Downloading Django-3.0.3-py3-none-any.whl (7.5 MB)
Collecting gunicorn==20.0.4
Downloading gunicorn-20.0.4-py2.py3-none-any.whl (77 kB)
Collecting asgiref~=3.2
Downloading asgiref-3.2.7-py2.py3-none-any.whl (19 kB)
Collecting sqlparse>=0.2.2
Downloading sqlparse-0.3.1-py2.py3-none-any.whl (40 kB)
Collecting pytz
Downloading pytz-2020.1-py2.py3-none-any.whl (510 kB)
Requirement already satisfied: setuptools>=3.0 in /usr/local/lib/python3.8/site-packages (from gunicorn==20.0.4->-r requirements.txt (line 3)) (47.1.1)
Installing collected packages: asgiref, sqlparse, pytz, django, gunicorn
Successfully installed asgiref-3.2.7 django-3.0.3 gunicorn-20.0.4 pytz-2020.1 sqlparse-0.3.1
Removing intermediate container b98bfa542add
---> d8e42dec362b
Step 7/12 : WORKDIR /app
---> Running in 8792e7122e72
Removing intermediate container 8792e7122e72
---> 8aa0ad5555db
Step 8/12 : ADD . /app
---> 532375700579
Step 9/12 : RUN useradd appuser && chown -R appuser /app
---> Running in 787e960c7fcf
Removing intermediate container 787e960c7fcf
---> ec803ab093be
Step 10/12 : USER appuser
---> Running in f47522f077db
Removing intermediate container f47522f077db
---> 45ca7aaacaed
Step 11/12 : CMD ["gunicorn", "--bind", "0.0.0.0:8000", "pythonPath.to.wsgi"]
---> Running in 0f17b93f74b9
Removing intermediate container 0f17b93f74b9
---> 66084c1ca8cd
Step 12/12 : LABEL com.microsoft.created-by=visual-studio-code
---> Running in 572ba3c87859
Removing intermediate container 572ba3c87859
---> d12cb3768345
Successfully built d12cb3768345
Successfully tagged pythonsamplevscodedjangotutorialtutorial:latest

Terminal will be reused by tasks, press any key to close it.

Executing task: docker-run: debug <

docker run -dt -P --name "pythonsamplevscodedjangotutorialtutorial-dev" --label "com.microsoft.created-by=visual-studio-code" -v "/home/serene/.vscode/extensions/ms-python.python-2020.5.86398/pythonFiles/lib/python/debugpy/no_wheels:/pydbg:ro" --entrypoint "python" "pythonsamplevscodedjangotutorialtutorial:latest" <

c8625dc8498cbf1df1ab714ed509df46b21244f84166abdb4e6466b4235b74d8

Terminal will be reused by tasks, press any key to close it.

"Python" terminals:

serene@serene:~$ env /usr/bin/python3 /home/serene/.vscode/extensions/ms-azuretools.vscode-docker-1.3.0/resources/python/launcher.py 0.0.0.0:44737 -- manage.py runserver 0.0.0.0:8000 --nothreading --noreload pythonsamplevscodedjangotutorialtutorial-dev
docker exec -d pythonsamplevscodedjangotutorialtutorial-dev python /pydbg/debugpy/launcher 0.0.0.0:44737 -- manage.py runserver 0.0.0.0:8000 --nothreading --noreload

[haniamr]

After doing some investigation, turns out for some reason the "bridge" network does not have a "gateway" property, and we expect to find that so the launcher can connect back to VSCode.

The workaround is to restart Docker:

sudo systemctl daemon-reload
sudo systemctl stop docker
sudo systemctl start docker

Here is a link to the related issue in Docker's repo: moby/moby#26799

[bwateratmsft]

@haniamr Thanks for investigating! I guess we can resolve this one as external? Unless there's something reasonable we can do as a workaround.

[haniamr]

@bwateratmsft sure thing. I guess we can resolve it as external, there isn't any workaround that I can think of apart of restarting the daemon as mentioned above.