Interview › Istio & Service Mesh
How does Istio enable a Zero Trust posture inside the cluster?
Istio & Service Mesh · Intermediate level
Answer
Istio enables zero trust by giving workloads strong identities, encrypting service-to-service traffic with mTLS, enforcing explicit authorization policies, validating request credentials, and producing audit-friendly telemetry for every service edge.
Technical explanation
Zero trust means the network location is not enough to trust a caller; identity and policy must be verified on each request path.
Istio can enforce service-account based access instead of relying only on pod IPs or flat cluster networking.
It should be combined with Kubernetes RBAC, NetworkPolicy, secret management, image security, and admission controls for a complete posture.
Hands-on example
Zero-trust rollout:
1. Standardize service accounts per workload.
2. Enable mTLS STRICT.
3. Create default-deny AuthorizationPolicy per namespace.
4. Add explicit ALLOW policies for known service edges.
5. Monitor denied traffic and fix legitimate flows through Git-reviewed policy changes.
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