[FIXED] why volumes not working correctly in docker whene i try to dockerize django app?

Issue

The issue arises when I attempt to proceed without using volumes; everything works correctly. However, when volumes are included, I get the following error:

django_app  | python: can't open file '/app/manage.py': [Errno 2] No such file or directory

docker-compose :

version: '3.8'
services:
  app:
    build: .
    volumes:
      - ./django:/app // the problem is here
    ports:
      - "8000:8000"
    image: app:django
    container_name: django_app
    command: python manage.py runserver 0.0.0.0:8000
    

dockerfile :

FROM python:3.12.1-slim

 
ENV PYTHONUNBUFFERED=1 

WORKDIR /app

COPY requirements.txt requirements.txt

RUN pip3 install -r requirements.txt

COPY . .

the commands that i use to build and run :

docker-compose build
docker-compose up

Solution

When I attempt to proceed without using volumes; everything works correctly.

Perfect. Do that.

More specifically, delete this block:

    volumes:
      - ./django:/app // the problem is here

This hides everything in the /app directory in the image, and replaces it with whatever happens to be in the django subdirectory of the directory containing the docker-compose.yml file. If different hosts have different versions of the application checked out, you'll get inconsistent results – this reintroduces the "works on my machine" problem that Docker frequently tries to avoid.

If the Dockerfile does any sort of rearrangement or manipulation of the source file, the bind mount will also hide this. I've seen Dockerfiles that try to correct DOS line endings or file permissions, for example, and the bind mount will hide those changes.

The more specific disconnect here seems to be that you're COPY . . the current directory into /app into the image, but then the bind mount hides that and replaces it with a ./django subdirectory. Bind-mounting a different subdirectory means that the container filesystem looks totally different from what's in the image. The command: override tries to run the script that's in ./django/manage.py on the host system. If the script is actually in the top-level directory, the bind mount hides the copy that's in the image.

Answered By - David Maze