As a platform engineer working with microservices, I recently faced a common but tricky challenge, implimenting the right TLS configuration for NATS messaging in our Kubernetes clusters. The main question was whether to terminate TLS at the ingress or implement end-to-end encryption, especially when dealing with both internal and external service communication.
Our Challenge
Our setup involved:
- Multiple Kubernetes clusters
- Microservices communicating via NATS
- Both internal (same cluster) and external (cross-cluster) communication
- Need for secure communication throughout
Understanding the Options
After some research and experimentation, I discovered three primary patterns for implementing TLS with NATS in Kubernetes:
1. Ingress-Only TLS Termination
- TLS terminates at ingress
- Plain traffic inside the cluster
- Internal clients connect directly without TLS
- Simplest setup, but less secure
2. Double TLS Termination
- TLS terminates at ingress
- New TLS connection from ingress to NATS cluster
- Internal clients must use TLS
- Balance of security and complexity
3. TLS Passthrough
- TLS traffic passes through ingress
- Terminates directly at NATS servers
- Most secure option
- Internal clients connect with TLS directly to NATS
Our Solution
We opted for the second approach (Double TLS Termination) because:
- It provided adequate security for our use case
- Maintained consistency in how services connect to NATS
- Simplified certificate management compared to end-to-end TLS
- Allowed for easier debugging at the ingress level
Key Learnings
- TLS configuration isn’t one-size-fits-all
- Consider your security requirements carefully
- Internal cluster traffic might have different security needs than external traffic
- NATS flexibility allows for various security patterns
Implementation Tips
- Use Kubernetes secrets for certificate management
- Consider using cert-manager for certificate automation
- Document your TLS architecture clearly
- Monitor TLS certificate expiration
References
- NATS Official Documentation on TLS Configuration
- Kubernetes Ingress TLS Documentation
- NATS Security Documentation
This article is written by Ajay from Pegasus Solutions, and is based on NATS 2.x and Kubernetes 1.25+
