implementing-service-mesh

Install a mesh such as Istio Ambient, Linkerd, or Cilium, then enable mTLS namespace-wide. For Istio, apply a PeerAuthentication resource with mode STRICT; Linkerd enables automatic mTLS by default once the namespace is annotated for injection.

Istio Ambient suits enterprise multi-cluster needs with about 8% latency overhead. Linkerd offers the simplest operation with 33% overhead, ideal for smaller teams. Cilium provides eBPF kernel-level enforcement for advanced networking but with higher latency overhead.

Define subsets in a DestinationRule for each version, then set traffic weights in a VirtualService, such as 90% to v1 and 10% to v2. For automated analysis and rollback, use Flagger with metric thresholds on success rate and latency.

Yes, Istio Ambient handles L4 mTLS through per-node ztunnel proxies and adds optional per-namespace waypoint proxies for L7 HTTP routing. This avoids per-pod sidecars while retaining routing capabilities where needed.

Common causes include namespaces not labeled or annotated for mesh injection, PERMISSIVE mode accepting plaintext silently, or mismatched authorization policies. Verify with istioctl authn tls-check, linkerd edges, or cilium bpf auth list depending on your mesh.

Avoid a mesh for simple single-cluster applications with few services, where the operational overhead outweighs benefits. Also avoid migrating between mesh implementations mid-project, as running parallel meshes is complex and error-prone.