Most Kubernetes clusters rely on NetworkPolicies for security. While NetworkPolicies are useful, they only control which pods can talk to which pods at the network level. They do not verify identity, encrypt traffic, or enforce fine-grained authorization. A compromised pod in an allowed namespace can impersonate any service.
What Zero Trust Means for Kubernetes
Zero trust in Kubernetes means every pod has a verifiable cryptographic identity (not just a service account token), all pod-to-pod communication is encrypted with mutual TLS, authorization decisions are based on verified identity and context (not just namespace or label), and identities are short-lived and automatically rotated.
The Stack: SPIRE + Envoy + OPA
- SPIRE: Issues cryptographic identities (X.509-SVIDs) to every pod via the SPIFFE Workload API
- Envoy (sidecar proxy): Handles mTLS transparently — applications do not need to implement TLS themselves
- OPA (Open Policy Agent): Enforces fine-grained authorization policies based on SPIFFE IDs
Why NetworkPolicies Are Not Enough
| Feature | NetworkPolicy | SPIRE + mTLS + OPA |
|---|---|---|
| Identity verification | No | Cryptographic (X.509) |
| Encryption | No | mTLS (automatic) |
| Authorization granularity | Namespace/label | Per-service, per-method |
| Works across clusters | No | Yes (SPIFFE federation) |
| Audit trail | Limited | Full (identity + policy logs) |
Learn Zero Trust Kubernetes
Module 5 of our free course deploys SPIRE on Kubernetes, registers workloads, and retrieves SVIDs inside pods. Modules 7-8 add Envoy integration and OPA policy enforcement for a complete zero trust stack.