Debugging python in docker container using debugpy and vs code results in timeout/connection refused - python-3.x

Question

I'm trying to setup native debugging for a python script running in docker for Visual Studio Code using debugpy. Ideally I'd like to just F5 and be on my way (including a build phase if needed). Currently I'm bouncing between a timeout caused from debugpy.listen(5678) inlined within the VS code editor itself (Exception has occurred: RuntimeError timed out waiting for adapter to connect) or a connection refused.
I created a launch.json from the documentation provided by microsoft:
launch.json
{
"version": "0.2.0",
"configurations": [
{
"name": "Attach to Integration (test)",
"type": "python",
"request": "attach",
"pathMappings": [
{
"localRoot": "${workspaceFolder}/test",
"remoteRoot": "/test"
}
],
"port": 5678,
"host": "127.0.0.1"
}
]
}
building the image looks like this so far:
Dockerfile
FROM python:3.7-slim-buster as base
RUN apt-get -y update; apt-get install -y vim git cmake
WORKDIR /
RUN mkdir .cache src in out config log
COPY requirements.txt .
RUN pip install -r requirements.txt; rm requirements.txt
#! TODO: config folder needs to be a mapped volume so they can change creds without rebuild
WORKDIR /src
COPY test ../test
COPY config ../config
COPY src/ .
#? D E B U G I M A G E
FROM base as debug
RUN pip install debugpy
CMD python -m debugpy --listen 0.0.0.0:5678 ../test/edu.employer._test.py
#! P R O D U C T I O N I M A G E
# FROM base as prod
# CMD [ "python", "/test/edu.employer._test.py" ]
Some examples I found try to simply things with a docker-compose.yaml, but I'm unsure if i need one at this point.
docker-compose.yaml
services:
tester:
container_name: tester
image: employer/test:1.0.0
build:
context: .
target: debug
dockerfile: test/edu.employer._test.Dockerfile
volumes:
- ./out:/out
- ./.cache:/.cache
- ./log:/log
ports:
- 5678:5678
which I based off a the CLI command: docker run -it -v $(pwd)/out:/out -v $(pwd)/.cache:/.cache -v $(pwd)/log:/log employer/test:1.0.0;
"critical" parts of my script just listen and wait for the bugger:
from __future__ import absolute_import
# Standard
import os
import sys
# 3rd Party
import debugpy
debugpy.listen(5678)
debugpy.wait_for_client()
# 1st Party. NOTE: All source files are in /src, so we can add that path here for testing
# and batch import all integrations files. Not very clean however
sys.path.insert(0, os.path.join('/', 'src'))
import integrations as ints

Answer 1

You have to configure the debugger with: debugpy.listen(("0.0.0.0", 5678)).
This happens because, by default, debugpy is listening on localhost. If you have your docker container on another host you have to add 0.0.0.0.

Answer 2

Turns out I needed to create a tasks.json file and provide the details on running the image...
tasks.json
{
// See https://go.microsoft.com/fwlink/?LinkId=733558
// for the documentation about the tasks.json format
"version": "2.0.0",
"tasks": [
{
"type": "docker-run",
"label": "docker-run: debug",
"dependsOn": ["docker-build"],
"dockerRun": {
"image": "employer/test:1.0.0"
// "env": {
// "FLASK_APP": "path_to/flask_entry_point.py"
// }
},
"python": {
"args": [],
"file": "/test/edu.employer._test.py"
}
}
]
}
and define a preLaunchTask:
{
"name": "Docker: Python",
"type": "docker",
"request": "launch",
"preLaunchTask": "docker-run: debug",
"python": {
"pathMappings": [
{
"localRoot": "${workspaceFolder}/test",
"remoteRoot": "/test"
}
],
//"projectType": "django"
}
}