Docker packages your app and its dependencies into a container.

Benefits:

• consistent environments
• easier deploys
• simpler CI/CD

Minimal Dockerfile (example)

FROM python:3.12-slim
 
WORKDIR /app
 
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
 
COPY . .
 
ENV PORT=8000
 
CMD ["gunicorn", "wsgi:app", "--bind", "0.0.0.0:8000"]

FROM python:3.12-slim
 
WORKDIR /app
 
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
 
COPY . .
 
ENV PORT=8000
 
CMD ["gunicorn", "wsgi:app", "--bind", "0.0.0.0:8000"]

Notes

• Use Gunicorn inside the container (not flask runflask run)
• Expose port via platform settings
• Store secrets via environment variables, not baked into the image

Common improvements

• add a non-root user
• use multi-stage builds
• add health checks
• pin dependencies