Django failed in build. Not found in env

Question

Hi im using dockerfile to deploy my app.
My Dockerfile
> # Use an official Python runtime as a parent image
> FROM python:3.11.9
> 
> # Set environment variables
> ENV PYTHONDONTWRITEBYTECODE 1
> ENV PYTHONUNBUFFERED 1
> 
> # Set work directory
> WORKDIR /usr/src/app
> 
> # install system dependencies
> RUN apt-get update && apt-get upgrade -y && apt-get install -y netcat-openbsd gcc && apt-get clean
> 
> # Copy file
> COPY . /usr/src/app/
> RUN pip install -r requirements/production.txt
> 
> # Collect static files and migrate
> RUN python manage.py collectstatic --noinput --settings=config.settings.production
> RUN python manage.py migrate --settings=config.settings.production
> 
> # Run the application
> CMD ["gunicorn", "--workers=3", "config.wsgi"]

It failed here
>  File "/usr/src/app/config/settings/production.py", line 14, in 
> 
>     SECRET_KEY = env("DJANGO_SECRET_KEY")
> 
>                  ^^^^^^^^^^^^^^^^^^^^^^^^
> 
>   File "/usr/local/lib/python3.11/site-packages/environ/environ.py", line 199, in __call__
> 
>     return self.get_value(
> 
>            ^^^^^^^^^^^^^^^
> 
>   File "/usr/local/lib/python3.11/site-packages/environ/environ.py", line 392, in get_value
> 
>     raise ImproperlyConfigured(error_msg) from exc
> 
> django.core.exceptions.ImproperlyConfigured: Set the DJANGO_SECRET_KEY environment variable

I already put the variables in the project