fix(telemetry): record route patterns instead of request paths on HTTP metrics (#12557)

# Which Problems Are Solved - The `uri` label of `http.server.request_count` and `http.server.return_code_counter` holds the concrete request path, so every object ID served over a REST path becomes its own metric series. On our v4.16.2 instance `/debug/metrics` exposes 8,000 series, 4,467 of which (56%) belong to `http_server_return_code_counter_total` alone, spread over 4,390 distinct `uri` values such as `/v2/sessions/385063742120926058`. The set only grows with the number of objects the installation has served. - Paths matching no route are recorded verbatim, so unauthenticated scanner traffic (`/wp-json/`, `/login.php`, …) keeps adding series. - The grpc-gateway answers `405 Method Not Allowed` without going through the configured `errorHandler`, so those responses never reported a route pattern, not even before the regression. This is a regression, first shipped in v4.11.0; v4.10.1 is unaffected. #9286 introduced the mechanism, #9523 extended it to unknown paths, and #11435 removed it while reorganising the middleware packages: > Removed setting of URI to context in metric middleware. There were only setters and no getters. (Unused value) The getter was `*recorder.RequestURI` in `RegisterRequestCounter` / `RegisterRequestCodeCounter`, which the same PR replaced with `baseURI(r)`. Both ends went at once, so nothing failed. # How the Problems Are Solved - `metrics.WithRequestURIPattern` / `metrics.SetRequestURIPattern` are back, and `metrics.RequestURI` is now the single place deciding what to label with: the pattern a router reported, or the requested path if none did. `UnknownPath` moved to the metrics package so every surface shares one constant. - The HTTP metrics middleware prepares the context before passing the request on, which is the half that got dropped. - `setRequestURIPattern` in the grpc-gateway reports the pattern to metrics again, not only to tracing, and is now also called on the `405` branch. - Requests routed by chi (the OIDC endpoints) fall back to the pattern chi matched. That covers the RFC 7592 client configuration routes added in #12315 (`/oauth/v2/register/{client_id}`), which are templated on the client ID, and collapses unknown paths below the OIDC prefixes to `UNKNOWN_PATH` as well. Against the metrics dump from our instance, `http_server_return_code_counter_total` drops from 4,467 series to roughly 35, and the endpoint as a whole from 8,000 to about 3,570. # Additional Changes - Regression tests, which were missing and are the reason the revert went unnoticed: - `metrics`: resolution of the `uri` label, including that a pattern set on a derived context reaches the middleware. - `gateway`: every way the gateway can answer — success, error, unroutable path, wrong method. - `middleware`: both routing styles, i.e. a router reporting its own pattern and a chi routed request. - A doc comment on `SetRequestURIPattern` explaining that it is written by routers and read back by the middleware through the context, so it does not read as an unused setter again. # Additional Context - Closes #12556 - Restores #9286 and #9523 - Regressed in #11435 Co-authored-by: Cursor <[email protected]>
2026-11-06 22:32:16 +00:00 · 2026-08-07 17:23:56 +02:00
parent 9fa0cad9d9
commit 83854e80e0
6 changed files with 362 additions and 7 deletions
@@ -3,6 +3,7 @@ package middleware
 import (
 	"net/http"

+	"github.com/go-chi/chi/v5"
 	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"

 	"github.com/zitadel/zitadel/backend/v3/instrumentation"
@@ -37,7 +38,14 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	recorder := newStatusWriter(w)
+	// Requested paths contain object IDs and are therefore unbounded, so the router below
+	// gets the opportunity to report the route pattern it served the request with instead.
+	ctx := metrics.WithRequestURIPattern(r.Context())
+	r = r.WithContext(ctx)
 	h.handler.ServeHTTP(recorder, r)
+	if pattern := chiRoutePattern(r); pattern != "" {
+		metrics.SetRequestURIPattern(ctx, pattern)
+	}
 	if h.containsMetricsMethod(metrics.MetricTypeRequestCount) {
 		metrics.RegisterRequestCounter(recorder, r)
 	}
@@ -49,6 +57,24 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 }

+// chiRoutePattern returns the route pattern chi matched the request against, e.g.
+// "/oauth/v2/register/{client_id}", or [metrics.UnknownPath] if chi routed the request but
+// found no route for it. Routers that are not chi based report their pattern themselves
+// through [metrics.SetRequestURIPattern]; for those an empty string is returned.
+//
+// chi only knows the pattern once it routed the request, so this must be called after the
+// wrapped handler returned.
+func chiRoutePattern(r *http.Request) string {
+	routeCtx := chi.RouteContext(r.Context())
+	if routeCtx == nil {
+		return ""
+	}
+	if pattern := routeCtx.RoutePattern(); pattern != "" {
+		return pattern
+	}
+	return metrics.UnknownPath
+}
+
 func (h *Handler) containsMetricsMethod(method metrics.MetricType) bool {
 	for _, m := range h.methods {
 		if m == method {
@@ -0,0 +1,125 @@
+package middleware
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/zitadel/zitadel/backend/v3/instrumentation/metrics"
+)
+
+// TestMetricsHandler_reportedPattern covers routers that report their route pattern
+// themselves, such as the grpc-gateway. Without the context prepared by the handler their
+// report is lost and the requested path is recorded, which adds a metric series per object.
+func TestMetricsHandler_reportedPattern(t *testing.T) {
+	tests := []struct {
+		name    string
+		pattern string
+		want    string
+	}{
+		{
+			name: "router reports no pattern, path is recorded",
+			want: "/v2/sessions/385063742120926058",
+		},
+		{
+			name:    "router reports a pattern, pattern is recorded",
+			pattern: "/v2/sessions/{session_id}",
+			want:    "/v2/sessions/{session_id}",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var served *http.Request
+			handler := MetricsHandler([]metrics.MetricType{metrics.MetricTypeStatusCode})(
+				http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+					served = r
+					if tt.pattern != "" {
+						metrics.SetRequestURIPattern(r.Context(), tt.pattern)
+					}
+					w.WriteHeader(http.StatusNoContent)
+				}),
+			)
+
+			handler.ServeHTTP(httptest.NewRecorder(), httptest.NewRequest(http.MethodDelete, "/v2/sessions/385063742120926058", nil))
+
+			require.NotNil(t, served)
+			assert.Equal(t, tt.want, metrics.RequestURI(served))
+		})
+	}
+}
+
+// TestMetricsHandler_chiRoutePattern covers the routers that leave the pattern to chi, such
+// as the OIDC endpoints. Their client configuration endpoints are templated on the client
+// ID and any unknown path below their prefixes ends up here as well.
+func TestMetricsHandler_chiRoutePattern(t *testing.T) {
+	tests := []struct {
+		name       string
+		method     string
+		requestURI string
+		want       string
+	}{
+		{
+			name:       "static endpoint",
+			method:     http.MethodPost,
+			requestURI: "/oauth/v2/token",
+			want:       "/oauth/v2/token",
+		},
+		{
+			name:       "static endpoint with query",
+			method:     http.MethodGet,
+			requestURI: "/oauth/v2/authorize?client_id=1234&state=abcd",
+			want:       "/oauth/v2/authorize",
+		},
+		{
+			name:       "client configuration endpoint",
+			method:     http.MethodGet,
+			requestURI: "/oauth/v2/register/307534931347210241",
+			want:       "/oauth/v2/register/{client_id}",
+		},
+		{
+			name:       "unknown path",
+			method:     http.MethodGet,
+			requestURI: "/oauth/v2/junk",
+			want:       metrics.UnknownPath,
+		},
+		{
+			name:       "known path, unsupported method",
+			method:     http.MethodDelete,
+			requestURI: "/oauth/v2/token",
+			want:       metrics.UnknownPath,
+		},
+	}
+
+	// served is the request as the routed handler saw it. Reading the recorded URI from it
+	// after the router returned gives the value the metrics handler recorded, because the
+	// two share the context the metrics handler prepared.
+	var served *http.Request
+	respond := func(w http.ResponseWriter, r *http.Request) {
+		served = r
+		w.WriteHeader(http.StatusNoContent)
+	}
+
+	// Mirrors how the OIDC server nests its routes in the metrics handler.
+	router := chi.NewRouter()
+	router.Use(MetricsHandler([]metrics.MetricType{metrics.MetricTypeStatusCode}))
+	router.Post("/oauth/v2/token", respond)
+	router.Get("/oauth/v2/authorize", respond)
+	router.Get("/oauth/v2/register/{client_id}", respond)
+	router.NotFound(respond)
+	router.MethodNotAllowed(respond)
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			served = nil
+
+			router.ServeHTTP(httptest.NewRecorder(), httptest.NewRequest(tt.method, tt.requestURI, nil))
+
+			require.NotNil(t, served)
+			assert.Equal(t, tt.want, metrics.RequestURI(served))
+		})
+	}
+}