Docker Best Practices for Python Applications

Containerizing Python apps requires attention to image size, build time, and security.

Multi-Stage Builds

# Build stage
FROM python:3.11-slim as builder
WORKDIR /app
RUN pip install poetry
COPY pyproject.toml poetry.lock ./
RUN poetry export -f requirements.txt > requirements.txt

# Runtime stage
FROM python:3.11-slim
WORKDIR /app
COPY --from=builder /app/requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
CMD ["python", "-m", "uvicorn", "main:app", "--host", "0.0.0.0"]

Layer Caching

Order your Dockerfile commands from least to most frequently changing:

1. Base image selection
2. System dependencies
3. Python dependencies
4. Application code

Security Hardening

• Run as non-root user
• Use specific image tags, not latest
• Scan images for vulnerabilities
• Minimize installed packages