feat: add metrics

internal/prometheus.go

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2024 Jonas Kaninda
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package pkg
+
+import (
+	"github.com/gorilla/mux"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"net/http"
+	"strconv"
+)
+
+type PrometheusRoute struct {
+	name string
+	path string
+}
+
+var totalRequests = prometheus.NewCounterVec(
+	prometheus.CounterOpts{
+		Name: "http_requests_total",
+		Help: "Number of get requests.",
+	},
+	[]string{"path"},
+)
+
+var responseStatus = prometheus.NewCounterVec(
+	prometheus.CounterOpts{
+		Name: "response_status",
+		Help: "Status of HTTP response",
+	},
+	[]string{"status"},
+)
+
+var httpDuration = promauto.NewHistogramVec(prometheus.HistogramOpts{
+	Name: "http_response_time_seconds",
+	Help: "Duration of HTTP requests.",
+}, []string{"path"})
+
+func prometheusMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		route := mux.CurrentRoute(r)
+		path, _ := route.GetPathTemplate()
+		timer := prometheus.NewTimer(httpDuration.WithLabelValues(path))
+
+		responseStatus.WithLabelValues(strconv.Itoa(http.StatusOK)).Inc()
+		totalRequests.WithLabelValues(path).Inc()
+
+		timer.ObserveDuration()
+		next.ServeHTTP(w, r)
+	})
+
+}

internal/proxy.go

@@ -29,7 +29,7 @@ import (
 // ProxyHandler proxies requests to the backend
 func (proxyRoute ProxyRoute) ProxyHandler() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
-		logger.Info("%s %s %s %s", r.Method, getRealIP(r), r.URL, r.UserAgent())
+		logger.Info("%s %s %s %s", r.Method, getRealIP(r), r.URL.Path, r.UserAgent())
 		// Check Method if is allowed
 		if len(proxyRoute.methods) > 0 {
 			if !slices.Contains(proxyRoute.methods, r.Method) {

internal/route.go

@@ -20,9 +20,17 @@ import (
 	"github.com/jkaninda/goma-gateway/internal/middleware"
 	"github.com/jkaninda/goma-gateway/pkg/logger"
 	"github.com/jkaninda/goma-gateway/util"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"time"
 )
 
+func init() {
+	_ = prometheus.Register(totalRequests)
+	_ = prometheus.Register(responseStatus)
+	_ = prometheus.Register(httpDuration)
+}
+
 // Initialize the routes
 func (gatewayServer GatewayServer) Initialize() *mux.Router {
 	gateway := gatewayServer.gateway
@@ -32,11 +40,18 @@ func (gatewayServer GatewayServer) Initialize() *mux.Router {
 		DisableRouteHealthCheckError: gateway.DisableRouteHealthCheckError,
 		Routes:                       gateway.Routes,
 	}
+	if gateway.EnableMetrics {
+		// Prometheus endpoint
+		r.Path("/metrics").Handler(promhttp.Handler())
+		r.Use(prometheusMiddleware)
+	}
+
 	// Routes health check
 	if !gateway.DisableHealthCheckStatus {
 		r.HandleFunc("/healthz", heath.HealthCheckHandler).Methods("GET")
 		r.HandleFunc("/health/routes", heath.HealthCheckHandler).Methods("GET")
 	}
+
 	// Health check
 	r.HandleFunc("/health/live", heath.HealthReadyHandler).Methods("GET")
 	r.HandleFunc("/readyz", heath.HealthReadyHandler).Methods("GET")
@@ -223,6 +238,7 @@ func (gatewayServer GatewayServer) Initialize() *mux.Router {
 			} else {
 				router.PathPrefix("").Handler(proxyRoute.ProxyHandler())
 			}
+
 		} else {
 			logger.Error("Error, path is empty in route %s", route.Name)
 			logger.Error("Route path ignored: %s", route.Path)

internal/types.go

@@ -196,6 +196,7 @@ type Gateway struct {
 	DisableDisplayRouteOnStart bool `yaml:"disableDisplayRouteOnStart"`
 	// DisableKeepAlive allows enabling and disabling KeepALive server
 	DisableKeepAlive bool `yaml:"disableKeepAlive"`
+	EnableMetrics    bool `yaml:"enableMetrics"`
 	// InterceptErrors holds the status codes to intercept the error from backend
 	InterceptErrors []int `yaml:"interceptErrors"`
 	// Cors holds proxy global cors