Docker Security

Container Security Best Practices

• Use trusted base images from official repositories
• Minimize images — only include necessary binaries and files
• Run containers as non-root users
• Keep images and dependencies up to date
• Apply the principle of least privilege in all configurations

Managing User Permissions

By default, containers run as root, which can be a security risk. To run as a non-root user:

FROM node:18
RUN useradd -m appuser
USER appuser
CMD ["node", "app.js"]

Also, avoid adding users to the docker group unnecessarily on the host system.

Scanning Images for Vulnerabilities

Use tools to scan your Docker images before deployment:

• Docker Scout: Integrated into Docker Desktop and CLI
• Trivy (by Aqua): Lightweight, fast scanner
• Snyk: CLI and GitHub integration for CI scanning

Example: Scan with Trivy

trivy image myapp:latest

Securing Network Communication

• Use internal Docker networks for container communication
• Limit open ports and expose only what's needed
• Use TLS for communication with private registries
• Encrypt sensitive environment variables or use Docker secrets

Implementing Role-Based Access Control (RBAC)

When using Docker with tools like Portainer, Kubernetes, or hosted registries, enable RBAC to limit actions:

• Define roles (admin, dev, ops) with scoped access
• Limit registry access to specific teams or namespaces
• Audit container usage and changes

A secure Docker workflow includes hardened images, proper access control, ongoing vulnerability scanning, and least-privilege practices. Proactive security is essential for DevOps and production deployments.