feat(metrics): integrate Prometheus metrics into router and main

- /metrics endpoint via promhttp.Handler
- actionHandler: request counter, bytes counter, latency histogram, errors
- Gauge updater: queues/messages count per tenant every 15s
- All metrics labeled by tenant and/or operation

app/cmd/goaws.go

@@ -16,6 +16,7 @@ import (
 	"shared-sqs/app/billing"
 	"shared-sqs/app/conf"
 	"shared-sqs/app/gosqs"
+	"shared-sqs/app/metrics"
 	"shared-sqs/app/models"
 	"shared-sqs/app/persistence"
 	"shared-sqs/app/router"
@@ -136,6 +137,9 @@ func main() {
 	quit := make(chan bool)
 	go gosqs.PeriodicTasks(1*time.Second, quit)
 
+	// Metrics: gauge updater — пересчёт очередей/сообщений per tenant каждые 15 секунд
+	metrics.StartGaugeUpdater(15*time.Second, quit)
+
 	// HTTP сервер с таймаутами
 	srv := &http.Server{
 		Addr:         "0.0.0.0:" + port,

app/router/router.go

@@ -11,15 +11,19 @@ import (
 	"net/http"
 	"strings"
 
+	"time"
+
 	"shared-sqs/app/admin"
 	"shared-sqs/app/auth"
 	"shared-sqs/app/billing"
 	sqs "shared-sqs/app/gosqs"
 	"shared-sqs/app/interfaces"
+	"shared-sqs/app/metrics"
 	"shared-sqs/app/tenant"
 	"shared-sqs/app/ui"
 
 	"github.com/gorilla/mux"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	log "github.com/sirupsen/logrus"
 )
 
@@ -34,6 +38,9 @@ func New(tenantStore *tenant.TenantStore, adminToken string) http.Handler {
 	// /health — публичный, без auth
 	r.HandleFunc("/health", health).Methods("GET")
 
+	// /metrics — Prometheus endpoint для Victoria Metrics scrape
+	r.Handle("/metrics", promhttp.Handler()).Methods("GET")
+
 	// Admin API — Bearer token auth, регистрируется через AdminHandler
 	adminHandler := admin.NewHandler(tenantStore, adminToken)
 	adminHandler.RegisterRoutes(r)
@@ -124,6 +131,7 @@ func health(w http.ResponseWriter, req *http.Request) {
 
 func actionHandler(w http.ResponseWriter, req *http.Request) {
 	action := extractAction(req)
+	start := time.Now()
 	log.WithFields(log.Fields{
 		"action": action,
 		"url":    req.URL,
@@ -132,7 +140,11 @@ func actionHandler(w http.ResponseWriter, req *http.Request) {
 	if ok {
 		statusCode, responseBody := jsonFn(req)
 		encodeResponse(w, req, statusCode, responseBody)
-		// Billing: записываем каждую успешную SQS-операцию (async, no-op если billing выключен)
+
+		// Metrics: latency гистограмма для каждой операции
+		duration := time.Since(start).Seconds()
+		metrics.RequestDuration.WithLabelValues(action).Observe(duration)
+
 		if statusCode < 400 {
 			if t, _ := req.Context().Value(auth.TenantContextKey).(*tenant.Tenant); t != nil {
 				msgBytes := req.ContentLength
@@ -144,8 +156,15 @@ func actionHandler(w http.ResponseWriter, req *http.Request) {
 				if queueName == "" {
 					queueName = req.FormValue("QueueName")
 				}
+				// Billing: запись в PostgreSQL (async, no-op если billing выключен)
 				billing.RecordUsage(t.ID, action, queueName, 1, msgBytes)
+				// Prometheus counters: requests + bytes
+				metrics.RequestsTotal.WithLabelValues(t.ID, action).Inc()
+				metrics.RequestBytesTotal.WithLabelValues(t.ID, action).Add(float64(msgBytes))
 			}
+		} else {
+			// Prometheus: счётчик ошибок
+			metrics.ErrorsTotal.WithLabelValues(action).Inc()
 		}
 		return
 	}