TL;DR
Docker provides container runtime security while Kubernetes adds orchestration security features. Docker alone is simpler but lacks built-in secrets management, network policies, and RBAC. Kubernetes provides comprehensive security controls but adds complexity and requires expertise. For production deployments, Kubernetes (or managed Kubernetes) provides better security primitives; Docker alone works for development and simple deployments.
Docker and Kubernetes serve different purposes: Docker is a container runtime, while Kubernetes orchestrates containers at scale. The comparison is really about running Docker alone versus running Docker under Kubernetes. Understanding their security models helps you choose the right approach for your vibe-coded applications.
Security Feature Comparison
| Security Feature | Docker Alone | Kubernetes |
|---|---|---|
| Secrets Management | Basic (env vars) | Native Secrets + External integrations |
| Network Policies | Manual iptables | Declarative policies |
| RBAC | Not available | Built-in |
| Pod Security | N/A | Pod Security Standards |
| Image Scanning | Manual tooling | Admission controllers |
| Service Mesh | Not built-in | Istio, Linkerd integration |
| Audit Logging | Basic | Comprehensive |
| Complexity | Lower | Higher |
Secrets Management
Docker Secrets
Standalone Docker often uses environment variables for secrets, which isn't ideal (visible in process listings, logs). Docker Swarm has a secrets feature, but most production deployments use Kubernetes or external secret managers. Without orchestration, secrets management requires additional tooling.
Kubernetes Secrets
Kubernetes provides native Secrets objects with encryption at rest (when configured). External secrets operators can integrate with Vault, AWS Secrets Manager, or other providers. Secrets are mounted as files or environment variables with proper access controls through RBAC.
Network Security
Docker Networking
Docker provides basic network isolation through bridge networks. Fine-grained network policies require manual iptables rules or additional tools. Container-to-container communication within a network is typically unrestricted by default.
Kubernetes Network Policies
Kubernetes Network Policies provide declarative, pod-level traffic control. You can restrict ingress and egress traffic based on labels, namespaces, and IP blocks. This enables zero-trust networking where pods can only communicate with explicitly allowed services.
Choose Docker Alone When: You're running development environments, simple single-host deployments, or have limited orchestration needs. Docker's simplicity reduces configuration mistakes. Best for learning, prototypes, or applications where Kubernetes complexity isn't justified.
Choose Kubernetes When: You need production-grade security features like RBAC, network policies, and secrets management. Kubernetes provides comprehensive security primitives that would require significant tooling to replicate with Docker alone. Best for production deployments, multi-tenant environments, or applications requiring enterprise security.
Access Control
Kubernetes RBAC
Kubernetes Role-Based Access Control restricts what users and service accounts can do. You can limit who can deploy containers, access secrets, or modify configurations. This granularity is essential for enterprise environments with multiple teams sharing clusters.
Best Practices
- Use minimal base images and scan for vulnerabilities
- Never run containers as root
- Enable Kubernetes Pod Security Standards
- Implement network policies to restrict traffic
- Use external secrets managers for production
- Enable audit logging and monitor for anomalies
- Regularly update and patch container images
Should I use managed Kubernetes for security?
Managed Kubernetes (EKS, GKE, AKS) handles control plane security, updates, and often provides better defaults. For most organizations, managed Kubernetes reduces security burden compared to self-managed clusters.
Is Docker less secure than Kubernetes?
Docker provides solid container isolation. Kubernetes adds orchestration-level security features. A well-configured Docker deployment can be secure, but Kubernetes provides more built-in security primitives for complex environments.
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