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How does Istio handle multi-cluster service discovery at a high level?
Istio & Service Mesh · Intermediate level
Answer
At a high level, Istio multi-cluster service discovery lets workloads in one cluster discover and securely call services in another cluster. It uses shared or federated trust, endpoint discovery, east-west gateways where needed, and mesh configuration that understands multiple networks and clusters.
Technical explanation
Multi-cluster designs vary by network reachability, trust model, and control-plane topology.
A flat network is simpler; separate networks commonly require east-west gateways.
Operational concerns include identity, DNS, failover, locality, certificate trust, gateway capacity, and config ownership.
Hands-on example
Validation checklist:
1. Confirm clusters share trust or have configured trust bundles.
2. Confirm remote secrets or discovery integration.
3. Deploy sample service in cluster A and caller in cluster B.
4. Verify mTLS identity across clusters.
5. Test failover and locality by draining one cluster's endpoints.
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