python debug with docker-compose in vscode: Error: Could not locate a Flask application. Use the 'flask --app' option, 'FLASK_APP' environment variable, or a 'wsgi.py' or 'app.py' file in the current directory

[yezhengli-Mr9]

Thanks @jamescurtin for steps in https://medium.com/@lassebenninga/how-to-debug-flask-running-in-docker-compose-in-vs-code-ef37f0f516ee
I try to follow steps there to get familiar with python debug with docker-compose in vscode j2eeexpert2015/springbootdebug#1

1. Add the debugpy library to your Dockerfile

EXPOSE 2992
EXPOSE 5000
++ RUN pip install debugpy
CMD [ "npm", "start"]

https://github.com/jamescurtin/demo-cookiecutter-flask/blob/ef61ca4503c9a9c4de338034d94ba385afc34958/Dockerfile#L54-L56

2. Add the debugpy command to the launch script

-- "start": "run-script-os",
++ "start": "python -m debugpy --wait-for-client --listen 0.0.0.0:5678 -m flask run --host=0.0.0.0"

in https://github.com/jamescurtin/demo-cookiecutter-flask/blob/ef61ca4503c9a9c4de338034d94ba385afc34958/package.json#L9

3. Add the “Python: Remote Attach” option to launch.json so result exact same file:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Remote Attach",
            "type": "python",
            "request": "attach",
            "connect": {
                "host": "localhost",
                "port": 5678
            },
            "pathMappings": [
                {
                    "localRoot": "${workspaceFolder}",
                    "remoteRoot": "."
                }
            ],
            "justMyCode": true
        }
    ]
}

4. Expose port 5678 in docker-compose.yml

services:
  flask-dev:
    build:
      context: .
      target: development
      args:
        <<: *build_args
    image: "my_flask_app-development"
    ports:
      - "8080:5000"
      - "2992:2992"
++    - "5678:5678"
    <<: *default_volumes

https://github.com/jamescurtin/demo-cookiecutter-flask/blob/ef61ca4503c9a9c4de338034d94ba385afc34958/docker-compose.yml#L13-L24

5. tart the container and debugger

docker-compose build
docker-compose build
Building flask-dev
[+] Building 56.2s (24/24) FINISHED                                                                                                                                                          docker:default
 => [internal] load .dockerignore                                                                                                                                                                      0.0s
 => => transferring context: 2B                                                                                                                                                                        0.0s
 => [internal] load build definition from Dockerfile                                                                                                                                                   0.0s
 => => transferring dockerfile: 1.78kB                                                                                                                                                                 0.0s
 => [internal] load metadata for docker.io/library/node:20-buster-slim                                                                                                                                 0.9s
 => [internal] load metadata for docker.io/library/python:3.11-slim-buster                                                                                                                             1.0s
 => [internal] load build context                                                                                                                                                                      0.0s
 => => transferring context: 95.11kB                                                                                                                                                                   0.0s
 => [builder  1/15] FROM docker.io/library/python:3.11-slim-buster@sha256:c46b0ae5728c2247b99903098ade3176a58e274d9c7d2efeaaab3e0621a53935                                                            21.7s
 => => resolve docker.io/library/python:3.11-slim-buster@sha256:c46b0ae5728c2247b99903098ade3176a58e274d9c7d2efeaaab3e0621a53935                                                                       0.0s
 => => sha256:c46b0ae5728c2247b99903098ade3176a58e274d9c7d2efeaaab3e0621a53935 988B / 988B                                                                                                             0.0s
 => => sha256:b94af75d4ff65c50bf1b2119bca6d0ba707037bacd0cb75314801a6953c03241 1.37kB / 1.37kB                                                                                                         0.0s
 => => sha256:db841a2e8ab326bf1101c5714186094fa05d3277c5b2dbcec943dade361b269f 6.83kB / 6.83kB                                                                                                         0.0s
 => => sha256:8b91b88d557765cd8c6802668755a3f6dc4337b6ce15a17e4857139e5fc964f3 27.14MB / 27.14MB                                                                                                      20.4s
 => => sha256:824416e234237961c9c5d4f41dfe5b295a3c35a671ee52889bfb08d8e257ec4c 2.78MB / 2.78MB                                                                                                         3.5s
 => => sha256:482d64d97d4e63625e51301e23ca7ff526afaf40710da26704d9ce2e1a6168fa 12.00MB / 12.00MB                                                                                                       2.9s
 => => sha256:c87b3089b2ed5584d9a52ddf02017556958f287dd63945476fbcd191954e6faf 244B / 244B                                                                                                             3.0s
 => => sha256:91bdacd599c69598dd6fbd7f97f7059b565f6f3015a04b6ab9e8db254a41652c 3.38MB / 3.38MB                                                                                                         3.7s
 => => extracting sha256:8b91b88d557765cd8c6802668755a3f6dc4337b6ce15a17e4857139e5fc964f3                                                                                                              0.6s
 => => extracting sha256:824416e234237961c9c5d4f41dfe5b295a3c35a671ee52889bfb08d8e257ec4c                                                                                                              0.1s
 => => extracting sha256:482d64d97d4e63625e51301e23ca7ff526afaf40710da26704d9ce2e1a6168fa                                                                                                              0.2s
 => => extracting sha256:c87b3089b2ed5584d9a52ddf02017556958f287dd63945476fbcd191954e6faf                                                                                                              0.0s
 => => extracting sha256:91bdacd599c69598dd6fbd7f97f7059b565f6f3015a04b6ab9e8db254a41652c                                                                                                              0.2s
 => [node 1/1] FROM docker.io/library/node:20-buster-slim@sha256:d0acb10d0062944abd19d56d79f4953de6bba167b04c961c6eba6054fbc4990c                                                                     19.6s
 => => resolve docker.io/library/node:20-buster-slim@sha256:d0acb10d0062944abd19d56d79f4953de6bba167b04c961c6eba6054fbc4990c                                                                           0.0s
 => => sha256:d0acb10d0062944abd19d56d79f4953de6bba167b04c961c6eba6054fbc4990c 549B / 549B                                                                                                             0.0s
 => => sha256:f31eeec1562e60912424355ef3b2dc082346c3c7f6a956f1337c6a234f1c06f3 1.37kB / 1.37kB                                                                                                         0.0s
 => => sha256:afe23aad037311e07c276229da35a987375fcb6023194877975c6d7e8e1a055a 7.62kB / 7.62kB                                                                                                         0.0s
 => => sha256:faac0b3889808c27af96e662a1082eef35772c35dcee1c7334f5f5a22b4149d7 27.19MB / 27.19MB                                                                                                      18.1s
 => => sha256:477d7c8346e1afefc9fa26c61e951b3dec17f8e40c17f13433da7486f5068e42 4.19kB / 4.19kB                                                                                                         3.8s
 => => sha256:9620175e3d55a49550c205e8a6123fb2601e00d5ed8f9121f2e73e8a5d8152c7 40.46MB / 40.46MB                                                                                                      13.0s
 => => sha256:5804f87db643f8da1d653309a98d35bfe9e842ab408b70343d7324dd6944d9a9 2.67MB / 2.67MB                                                                                                        13.5s
 => => sha256:e12b69f2ed72122d28c7b16ab7e0f32d4ce164641c23206ad45a9940b30f4af7 453B / 453B                                                                                                            13.7s
 => => extracting sha256:faac0b3889808c27af96e662a1082eef35772c35dcee1c7334f5f5a22b4149d7                                                                                                              0.6s
 => => extracting sha256:477d7c8346e1afefc9fa26c61e951b3dec17f8e40c17f13433da7486f5068e42                                                                                                              0.0s
 => => extracting sha256:9620175e3d55a49550c205e8a6123fb2601e00d5ed8f9121f2e73e8a5d8152c7                                                                                                              0.6s
 => => extracting sha256:5804f87db643f8da1d653309a98d35bfe9e842ab408b70343d7324dd6944d9a9                                                                                                              0.0s
 => => extracting sha256:e12b69f2ed72122d28c7b16ab7e0f32d4ce164641c23206ad45a9940b30f4af7                                                                                                              0.0s
 => [builder  2/15] WORKDIR /app                                                                                                                                                                       0.2s
 => [builder  3/15] COPY --from=node /usr/local/bin/ /usr/local/bin/                                                                                                                                   0.2s
 => [builder  4/15] COPY --from=node /usr/lib/ /usr/lib/                                                                                                                                               0.1s
 => [builder  5/15] RUN true                                                                                                                                                                           0.3s
 => [builder  6/15] COPY --from=node /usr/local/lib/node_modules /usr/local/lib/node_modules                                                                                                           0.1s
 => [builder  7/15] COPY requirements requirements                                                                                                                                                     0.0s
 => [builder  8/15] RUN pip install --no-cache -r requirements/prod.txt                                                                                                                                7.0s
 => [builder  9/15] COPY package.json ./                                                                                                                                                               0.0s
 => [builder 10/15] RUN npm install                                                                                                                                                                   10.3s
 => [builder 11/15] COPY webpack.config.js autoapp.py ./                                                                                                                                               0.1s 
 => [builder 12/15] COPY my_flask_app my_flask_app                                                                                                                                                     0.0s 
 => [builder 13/15] COPY assets assets                                                                                                                                                                 0.0s 
 => [builder 14/15] COPY .env.example .env                                                                                                                                                             0.0s 
 => [builder 15/15] RUN npm run-script build                                                                                                                                                           3.8s
 => [development 1/2] RUN pip install --no-cache -r requirements/dev.txt                                                                                                                               5.9s
 => [development 2/2] RUN pip install debugpy                                                                                                                                                          2.0s
 => exporting to image                                                                                                                                                                                 3.4s
 => => exporting layers                                                                                                                                                                                3.4s
 => => writing image sha256:42e85e68acea7d471b3960908bf8f28b0df18db81b1542b821be1df565c916b6                                                                                                           0.0s
 => => naming to docker.io/library/my_flask_app-development                                                                                                                                            0.0s
Building flask-prod
[+] Building 9.2s (30/30) FINISHED                                                                                                                                                           docker:default
 => [internal] load build definition from Dockerfile                                                                                                                                                   0.0s
 => => transferring dockerfile: 1.78kB                                                                                                                                                                 0.0s
 => [internal] load .dockerignore                                                                                                                                                                      0.0s
 => => transferring context: 2B                                                                                                                                                                        0.0s
 => [internal] load metadata for docker.io/library/python:3.11-slim-buster                                                                                                                             0.3s
 => [internal] load metadata for docker.io/library/node:20-buster-slim                                                                                                                                 0.3s
 => [internal] load build context                                                                                                                                                                      0.1s
 => => transferring context: 342.64kB                                                                                                                                                                  0.1s
 => [builder  1/15] FROM docker.io/library/python:3.11-slim-buster@sha256:c46b0ae5728c2247b99903098ade3176a58e274d9c7d2efeaaab3e0621a53935                                                             0.0s
 => [node 1/1] FROM docker.io/library/node:20-buster-slim@sha256:d0acb10d0062944abd19d56d79f4953de6bba167b04c961c6eba6054fbc4990c                                                                      0.0s
 => CACHED [builder  2/15] WORKDIR /app                                                                                                                                                                0.0s
 => [production  3/10] RUN useradd -m sid                                                                                                                                                              0.3s
 => CACHED [builder  3/15] COPY --from=node /usr/local/bin/ /usr/local/bin/                                                                                                                            0.0s
 => CACHED [builder  4/15] COPY --from=node /usr/lib/ /usr/lib/                                                                                                                                        0.0s
 => CACHED [builder  5/15] RUN true                                                                                                                                                                    0.0s
 => CACHED [builder  6/15] COPY --from=node /usr/local/lib/node_modules /usr/local/lib/node_modules                                                                                                    0.0s
 => CACHED [builder  7/15] COPY requirements requirements                                                                                                                                              0.0s
 => CACHED [builder  8/15] RUN pip install --no-cache -r requirements/prod.txt                                                                                                                         0.0s
 => CACHED [builder  9/15] COPY package.json ./                                                                                                                                                        0.0s
 => CACHED [builder 10/15] RUN npm install                                                                                                                                                             0.0s
 => CACHED [builder 11/15] COPY webpack.config.js autoapp.py ./                                                                                                                                        0.0s
 => CACHED [builder 12/15] COPY my_flask_app my_flask_app                                                                                                                                              0.0s
 => CACHED [builder 13/15] COPY assets assets                                                                                                                                                          0.0s
 => CACHED [builder 14/15] COPY .env.example .env                                                                                                                                                      0.0s
 => CACHED [builder 15/15] RUN npm run-script build                                                                                                                                                    0.0s
 => [production  4/10] RUN chown -R sid:sid /app                                                                                                                                                       0.3s
 => [production  5/10] COPY --from=builder --chown=sid:sid /app/my_flask_app/static /app/my_flask_app/static                                                                                           0.1s
 => [production  6/10] COPY requirements requirements                                                                                                                                                  0.0s
 => [production  7/10] RUN pip install --no-cache --user -r requirements/prod.txt                                                                                                                      7.2s
 => [production  8/10] COPY supervisord.conf /etc/supervisor/supervisord.conf                                                                                                                          0.1s
 => [production  9/10] COPY supervisord_programs /etc/supervisor/conf.d                                                                                                                                0.0s 
 => [production 10/10] COPY . .                                                                                                                                                                        0.0s 
 => exporting to image                                                                                                                                                                                 0.7s 
 => => exporting layers                                                                                                                                                                                0.7s 
 => => writing image sha256:3362d9c720d9bef018d60fde317688a382b64b02b220bf003fea2e8dd3cb8a7d                                                                                                           0.0s 
 => => naming to docker.io/library/my_flask_app-production                                                                                                                                             0.0s
Building manage
[+] Building 0.3s (24/24) FINISHED                                                                                                                                                           docker:default
 => [internal] load build definition from Dockerfile                                                                                                                                                   0.0s
 => => transferring dockerfile: 1.78kB                                                                                                                                                                 0.0s
 => [internal] load .dockerignore                                                                                                                                                                      0.0s
 => => transferring context: 2B                                                                                                                                                                        0.0s
 => [internal] load metadata for docker.io/library/node:20-buster-slim                                                                                                                                 0.3s
 => [internal] load metadata for docker.io/library/python:3.11-slim-buster                                                                                                                             0.3s
 => [internal] load build context                                                                                                                                                                      0.0s
 => => transferring context: 2.16kB                                                                                                                                                                    0.0s
 => [node 1/1] FROM docker.io/library/node:20-buster-slim@sha256:d0acb10d0062944abd19d56d79f4953de6bba167b04c961c6eba6054fbc4990c                                                                      0.0s
 => [builder  1/15] FROM docker.io/library/python:3.11-slim-buster@sha256:c46b0ae5728c2247b99903098ade3176a58e274d9c7d2efeaaab3e0621a53935                                                             0.0s
 => CACHED [builder  2/15] WORKDIR /app                                                                                                                                                                0.0s
 => CACHED [builder  3/15] COPY --from=node /usr/local/bin/ /usr/local/bin/                                                                                                                            0.0s
 => CACHED [builder  4/15] COPY --from=node /usr/lib/ /usr/lib/                                                                                                                                        0.0s
 => CACHED [builder  5/15] RUN true                                                                                                                                                                    0.0s
 => CACHED [builder  6/15] COPY --from=node /usr/local/lib/node_modules /usr/local/lib/node_modules                                                                                                    0.0s
 => CACHED [builder  7/15] COPY requirements requirements                                                                                                                                              0.0s
 => CACHED [builder  8/15] RUN pip install --no-cache -r requirements/prod.txt                                                                                                                         0.0s
 => CACHED [builder  9/15] COPY package.json ./                                                                                                                                                        0.0s
 => CACHED [builder 10/15] RUN npm install                                                                                                                                                             0.0s
 => CACHED [builder 11/15] COPY webpack.config.js autoapp.py ./                                                                                                                                        0.0s
 => CACHED [builder 12/15] COPY my_flask_app my_flask_app                                                                                                                                              0.0s
 => CACHED [builder 13/15] COPY assets assets                                                                                                                                                          0.0s
 => CACHED [builder 14/15] COPY .env.example .env                                                                                                                                                      0.0s
 => CACHED [builder 15/15] RUN npm run-script build                                                                                                                                                    0.0s
 => CACHED [development 1/2] RUN pip install --no-cache -r requirements/dev.txt                                                                                                                        0.0s
 => CACHED [development 2/2] RUN pip install debugpy                                                                                                                                                   0.0s
 => exporting to image                                                                                                                                                                                 0.0s
 => => exporting layers                                                                                                                                                                                0.0s
 => => writing image sha256:42e85e68acea7d471b3960908bf8f28b0df18db81b1542b821be1df565c916b6                                                                                                           0.0s
 => => naming to docker.io/library/my_flask_app-manage                                            

and then

docker-compose up flask-dev
Starting demo-cookiecutter-flask_flask-dev_1 ... done
Attaching to demo-cookiecutter-flask_flask-dev_1
flask-dev_1   | 
flask-dev_1   | > my_flask_app@1.0.0 start
flask-dev_1   | > python -m debugpy --wait-for-client --listen 0.0.0.0:5678 -m flask run --host=0.0.0.0
flask-dev_1   | 
flask-dev_1   | 0.00s - Debugger warning: It seems that frozen modules are being used, which may
flask-dev_1   | 0.00s - make the debugger miss breakpoints. Please pass -Xfrozen_modules=off
flask-dev_1   | 0.00s - to python to disable frozen modules.
flask-dev_1   | 0.00s - Note: Debugging will proceed. Set PYDEVD_DISABLE_FILE_VALIDATION=1 to disable this validation.
flask-dev_1   | Usage: python -m flask run [OPTIONS]
flask-dev_1   | Try 'python -m flask run --help' for help.
flask-dev_1   | 
flask-dev_1   | Error: Could not locate a Flask application. Use the 'flask --app' option, 'FLASK_APP' environment variable, or a 'wsgi.py' or 'app.py' file in the current directory.
demo-cookiecutter-flask_flask-dev_1 exited with code 2

Project configuration:

Option	Values
use_pipenv	yes no
python_version	3.11 3.10 3.9 3.8
node_version	20 18 node -v v12.22.9; npm -v 8.5.1
use_heroku	yes no
Are you using Docker to run the app?	yes no

[yezhengli-Mr9]

Step 1,2 are consistent with hints in https://code.visualstudio.com/docs/containers/docker-compose for python