Label HTTP metrics with the chi route pattern (closes #254)

internal/middleware/middleware.go

@@ -13,9 +13,6 @@ import (
 	"github.com/go-chi/chi"
 	"github.com/go-chi/chi/middleware"
 	"github.com/go-chi/cors"
-	metrics "github.com/slok/go-http-metrics/metrics/prometheus"
-	ghmm "github.com/slok/go-http-metrics/middleware"
-	"github.com/slok/go-http-metrics/middleware/std"
 	"go.uber.org/fx"
 	"sneak.berlin/go/webhooker/internal/config"
 	"sneak.berlin/go/webhooker/internal/globals"
@@ -29,10 +26,15 @@ const (
 	// preflight response can be cached.
 	corsMaxAge = 300
 
-	// unmatchedRoute is logged in the access log's url field when a
-	// redirected or rejected request matched no route pattern at
-	// all. Every byte of such a path is client-chosen, so none of it
-	// is logged.
+	// unmatchedRoute stands in for a request that matched no route
+	// pattern at all. Every byte of such a path is client-chosen, so
+	// none of it is kept.
+	//
+	// It is the access log's url field on a redirected or rejected
+	// request, and it is the metrics `handler` label on the same
+	// request; see metrics.go. Both surfaces are written once per
+	// request from a path the client picks, so both have to collapse
+	// the unmatched case into one fixed value.
 	unmatchedRoute = "(unmatched)"
 
 	// redactedQuery stands in for the query string on the access log
@@ -438,17 +440,6 @@ func (s *Middleware) RequireAuth() func(http.Handler) http.Handler {
 	}
 }
 
-// Metrics returns middleware that records Prometheus HTTP metrics.
-func (s *Middleware) Metrics() func(http.Handler) http.Handler {
-	mdlw := ghmm.New(ghmm.Config{
-		Recorder: metrics.NewRecorder(metrics.Config{}),
-	})
-
-	return func(next http.Handler) http.Handler {
-		return std.Handler("", mdlw, next)
-	}
-}
-
 // MetricsAuth returns middleware that protects metrics endpoints
 // with basic auth.
 func (s *Middleware) MetricsAuth() func(http.Handler) http.Handler {