Docker Container Security Best Practices

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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.