fix: avoid creating a new endpoint in prometheus for each urls

middleware/metrics.go

@@ -1,19 +1,31 @@
 package middleware
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/gin-gonic/gin"
 	"github.com/prometheus/client_golang/prometheus"
 )
 
+type RouteKey struct{}
+
+func Route(route string) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		c.Request = c.Request.WithContext(context.WithValue(c.Request.Context(), RouteKey{}, route))
+		c.Next()
+	}
+}
+
 func Metrics(c *gin.Context) {
 	c.Next()
-	customMetrics.histogram.WithLabelValues(
-		c.Request.Method,
-		c.Request.URL.String(),
-		fmt.Sprint(c.Writer.Status()))
-
+	route, ok := c.Request.Context().Value(RouteKey{}).(string)
+	if ok {
+		customMetrics.histogram.WithLabelValues(
+			c.Request.Method,
+			route,
+			fmt.Sprint(c.Writer.Status()))
+	}
 }
 
 var customMetrics = newMetrics()

server/http.go

@@ -53,16 +53,19 @@ func (s *HTTPServer) Init() error {
 				pattern: "redirect",
 				handler: failure.Handle(handlers.redirect),
 				method:  router.GET,
+				route:   "redirect",
 			},
 			{
 				pattern: "display",
 				handler: failure.Handle(handlers.display),
 				method:  router.GET,
+				route:   "display",
 			},
 			{
 				pattern: "get",
 				handler: failure.Handle(handlers.get),
 				method:  router.GET,
+				route:   "get",
 			},
 		}
 	)
@@ -146,6 +149,7 @@ func (s *HTTPServer) Init() error {
 			middleware.URLParser(s.config.Options.MimetypeDetector, s.processor),
 			middleware.OperationParser(),
 			middleware.RestrictSizes(s.config.Options.AllowedSizes),
+			middleware.Route(e.route),
 			e.handler,
 		}
 

server/types.go

@@ -7,4 +7,5 @@ type endpoint struct {
 	handler gin.HandlerFunc
 	method  handlerMethod
 	pattern string
+	route   string
 }