feat: automatic HTTP/gRPC request metrics#4
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…dleware seam The prometheus bundle exposed RecordHTTPRequest/RecordGRPCRequest but nothing called them outside the example, so "automatic metrics" weren't automatic. Add a bundle-time extension seam on framework.App — AddUnaryInterceptor, AddStreamInterceptor, and AddHTTPMiddleware — that bundles can call from Initialize (which always runs before the gRPC/HTTP servers are built), with safe no-ops if called after server construction. AddHTTPMiddleware wraps the full handler built by startHTTPServer (health, metrics, pprof, and user HTTPRegistrar routes). Wire the prometheus bundle's Initialize to register a gRPC interceptor pair (status derived from google.golang.org/grpc/status) and an HTTP middleware that records duration/status against RecordGRPCRequest/RecordHTTPRequest for every call, with no per-handler code required. The HTTP endpoint label prefers the low-cardinality r.Pattern (Go 1.22+ ServeMux route template), falling back to the raw path only for unmatched requests. Manual RecordHTTPRequest/RecordGRPCRequest calls remain fully supported.
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Closes the review's "automatic metrics aren't automatic" gap (M4). Adding the prometheus bundle now records request metrics with zero per-handler code.
New framework seam
Bundles receive
*AppinInitialize(which runs before servers are built) but previously had no way to add interceptors or middleware post-construction. Added:AddUnaryInterceptor/AddStreamInterceptor— append to the gRPC interceptor chainsAddHTTPMiddleware(func(http.Handler) http.Handler)— ordered middleware applied around the HTTP mux (health, metrics, pprof, and user routes)All three are no-ops if called after the relevant server is built, and append under the app lock.
Prometheus wiring
Initializeregisters a gRPC unary+stream interceptor (status label fromstatus.Code(err).String()) whenEnableGRPCMetrics, and an HTTP middleware whenEnableHTTPMetrics. ManualRecordHTTPRequest/RecordGRPCRequeststill work — purely additive.Cardinality: the HTTP endpoint label uses
r.Pattern(Go 1.22+ matched route template, e.g.GET /users/{id}), falling back to the raw path only for unmatched 404s.Tests
New framework seam tests (real gRPC call + real HTTP request through seam-added interceptor/middleware; no-op-after-build) and prometheus wiring tests (end-to-end counter increments via prometheus testutil, status derivation, pattern-vs-path labeling).
Full
-racesuite green, lint 0 issues.Note: a follow-up docs pass will document this new API and the now-true automatic-metrics claims.
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