Docker Container Security Best Practices
Image Security
Start with minimal base images like Alpine or distroless. Scan images for vulnerabilities using tools like Trivy or Snyk. Never run containers as root — use USER directive in Dockerfiles.
Build Security
Use multi-stage builds to minimize the attack surface. Pin base image versions with SHA256 digests. Never embed secrets in images — use Docker secrets or environment variables at runtime.
Runtime Security
Apply resource limits (CPU, memory) to prevent denial of service. Use read-only file systems where possible. Drop unnecessary Linux capabilities with --cap-drop=ALL and add only what is needed.
Network Security
Use Docker networks to isolate containers. Never expose unnecessary ports. Use TLS for inter-container communication in production environments.
Monitoring
Implement runtime security monitoring with Falco or Sysdig. Log container activity and set up alerts for suspicious behavior. Regularly audit container configurations.