Docker Best Practices

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Dockerfile Best Practices(DOCUMENTATION)

Introduction

Following Docker best practices ensures secure, efficient, and reproducible containers.

Key Practices

Run as Non-Root User

dockerfile
RUN adduser --disabled-password appuser
RUN chown -R appuser:appuser /app
USER appuser

Use .dockerignore

.git
.env*
*.pyc
__pycache__
media/*
staticfiles/*

Pin Dependencies

dockerfile
FROM python:3.11.6-slim  # Specific version
RUN pip install django==6.0.1  # Pinned versions

Minimize Layers

dockerfile
# Bad: Multiple RUN commands
RUN apt-get update
RUN apt-get install -y gcc
RUN apt-get clean

# Good: Combined
RUN apt-get update && \
    apt-get install -y gcc && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

Environment Variables

dockerfile
ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONUNBUFFERED=1

Best Practices

  1. Non-root user: Security best practice.
  2. Multi-stage builds: Smaller, more secure images.
  3. Pin versions: Reproducible builds.
  4. Use .dockerignore: Faster builds, smaller context.

Summary

Build secure Docker images by running as non-root, using multi-stage builds, pinning versions, and minimizing layers. Always use .dockerignore to exclude unnecessary files.

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