Dockerfile

# Dockerfile
FROM python:3.11-slim

ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONUNBUFFERED=1

WORKDIR /app

# Install system deps so pg_isready and psycopg2 can work
RUN apt-get update && apt-get install -y \
    gcc \
    libpq-dev \
    postgresql-client \
  && rm -rf /var/lib/apt/lists/*

# Python deps
COPY requirements.txt /app/
RUN pip install --no-cache-dir -r requirements.txt

# Copy project
COPY . /app/

# sensible defaults (can be overridden by docker-compose env)
ENV DATABASE_HOST=db
ENV DATABASE_PORT=5432
ENV POSTGRES_DB=mydb
ENV POSTGRES_USER=postgres
ENV POSTGRES_PASSWORD=123

# Wait for DB, run migrations, then start server
CMD ["sh", "-c", "until pg_isready -h \"$DATABASE_HOST\" -p \"$DATABASE_PORT\"; do echo 'Waiting for DB...'; sleep 1; done; python manage.py migrate --noinput; python manage.py runserver 0.0.0.0:8000"]