Container Security: Docker and Kubernetes Best Practices
Containers (Docker) and container orchestration (Kubernetes) have transformed software deployment — but they introduce their own security considerations. Misconfigured containers are a leading cause of cloud infrastructure compromise.
Container Image Security
- Minimal base images: Use minimal base images (distroless, Alpine) to reduce the attack surface — fewer installed packages means fewer vulnerabilities
- No root processes: Run container processes as a non-root user — limits the impact if the container is compromised
- Image scanning: Scan images for known CVEs (Trivy, Snyk Container) before and after build — integrate into CI/CD pipeline
- Image signing: Sign images and verify signatures before deployment to prevent tampering
- Immutable images: Container images should not be modified after build — updates require building and deploying a new image
Runtime Security
- Read-only filesystems: Mount container filesystems as read-only where possible — applications that need to write use specific mounted volumes
- Resource limits: Set CPU and memory limits to prevent one compromised container from affecting others
- Network policies: Kubernetes network policies control which pods can communicate — implement least-privilege network access
- Secrets management: Use Kubernetes Secrets (encrypted at rest) or an external secrets manager — do not embed secrets in environment variables defined in manifests
Kubernetes-Specific Practices
- Enable RBAC and use minimal permissions for service accounts
- Use Pod Security Standards to enforce security constraints on workloads
- Enable audit logging on the API server
- Regularly update Kubernetes and node OS