I’m working inside a flask micro service which is running inside a docker container.

The app structure is

├── README.md
├── pricing-compose-dev.yml
├── pricing-compose.yml
└── pricing_gateway
    ├── Dockerfile-slim-bullseye-python312
    ├── app_pricing_gateway.py
    ├── debugger.py
    ├── pywsgi.py
    ├── requirements.txt
    .
    .
    .

Here, I use the pricing-compose-dev.yml to run my local environment. It seems like this

version: "3.8"

services:

  pricing_gateway:
    container_name: pricing_gateway
    init: true
    restart: unless-stopped
    ports:
      - "6062:3055"
      - "10001:10001"
    build:
      context: pricing_gateway
      dockerfile: Dockerfile-slim-bullseye-python312
    entrypoint: flask --app pywsgi.py run --debug
    env_file: .env
    volumes:
      - ./pricing_gateway:/app
    
  pricing_postgres:
    container_name: pricing_postgres
    image: postgres:14-alpine
    ports:
      - "6435:5432"
    expose:
      - "6435"
    volumes:
      - ~/pricing_app/postgres:/var/lib/postgresql/data 
    environment:
      - POSTGRES_PASSWORD=XXXX
      - POSTGRES_USER=XXXX
      - POSTGRES_DB=XXXX

The Dockerfile-slim-bullseye-python312 file contains

FROM python:3.12.0-slim-bullseye

WORKDIR /app

RUN apt-get update && apt-get install -y git
COPY . .
RUN pip3 install --no-cache-dir -r requirements.txt
RUN pip3 install debugpy

EXPOSE 3054

The entrypoint run the code inside pywsgi.py, that is

from gevent import monkey
monkey.patch_all()
from geventwebsocket.handler import WebSocketHandler
from gevent.pywsgi import WSGIServer
from app_pricing_gateway import app
import os

os.environ.update()
server = WSGIServer( ("0.0.0.0", 3054), app, handler_class=WebSocketHandler,)
server.serve_forever()

And it runs the code inside app_pricing_gateway

from flask import Flask, Blueprint
from graphql_server.flask import GraphQLView
from schemas.schema_protected import schema_protected
from system_setup import api as private_api
from carecart_pricing_ctx_database_sqlalchemy_14.models.base import db_session
from debugger import initialize_flask_server_debugger_if_needed

initialize_flask_server_debugger_if_needed()

app = Flask(__name__)

api_public = Blueprint('public_api', __name__)
app.register_blueprint(private_api, url_prefix='/protected/pricing')

app.add_url_rule('/protected/pricing/gateway_graphql', view_func=GraphQLView.as_view(
   'graphqlProtected',
   schema=schema_protected,
   graphiql=True,
))

@app.teardown_appcontext
def shutdown_session(exception=None):
    db_session.remove()

if __name__ == '__main__':
    app.run()

It use the function initialize_flask_server_debugger_if_needed which is defined in debugger.py

from os import getenv

def initialize_flask_server_debugger_if_needed():
    if getenv("DEBUGGER") == "True":
        import multiprocessing
         
        if multiprocessing.current_process().pid > 1:
            import debugpy

            debugpy.listen(("0.0.0.0", 10001))
            print("⏳ VS Code debugger can now be attached, press F5 in VS Code ⏳", flush=True)
            debugpy.wait_for_client()
            print("???? VS Code debugger attached, enjoy debugging ????", flush=True)

At least, to debug my application I use this configuration in my launch.json

    {
      "name": "Attach to Pricing",
      "type": "debugpy",
      "request": "attach",
      "connect": {
        "host": "127.0.0.1",
        "port": 10001
      },
      "pathMappings": [
        {
          "localRoot": "${workspaceFolder}/Pricing-Context-CareCart/pricing_gateway",
          "remoteRoot": "/app"
        }
      ]
    },

P.D: my requirements.txt file have the following libs

Flask = 2.3.3
.
.
.
debug-py

Everything works well. I can run my container, attach my debugger and debug without any problems my endpoints.

The problem happens when I change something in the code. I want it to automatically reload, and not need to make the build again manually.

I read that with the option --debug should be enough, but it doesn’t seems to work.

I also tried adding the environment variables

FLASK_DEBUG=1
FLASK_ENV=development