Part 9
2 chapters
Observability, Mesh & Load Balancing
Trace an RPC across the REST to gRPC seam and run gRPC correctly behind Kubernetes.
Chapter 21
Observability
OpenTelemetry tracing and Micrometer/Prometheus metrics riding across the REST-to-gRPC seam in call metadata, plus the library's own grpc.health.v1.Health check — no contract change, no manual propagation code
Chapter 22
Load balancing & service mesh
The L4 single-connection problem behind a plain Kubernetes Service, the client-side (headless + round_robin) and mesh (Istio/Envoy) fixes, and STRICT mTLS + retries/timeouts — run by hand on minikube.