feat: add basic prometheus metrics integration

internal/admin/server.go

@@ -16,6 +16,7 @@ import (
 	"github.com/go-chi/chi/v5/middleware"
 	"github.com/go-chi/cors"
 	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"gitlab.com/wpetit/goweb/logger"
 )
 
@@ -101,6 +102,25 @@ func (s *Server) run(parentCtx context.Context, addrs chan net.Addr, errs chan e
 
 	router.Use(corsMiddleware.Handler)
 
+	if s.serverConfig.Metrics.Enabled {
+		metrics := s.serverConfig.Metrics
+
+		logger.Info(ctx, "enabling metrics", logger.F("endpoint", metrics.Endpoint))
+
+		router.Group(func(r chi.Router) {
+			if metrics.BasicAuth != nil {
+				logger.Info(ctx, "enabling authentication on metrics endpoint")
+
+				r.Use(middleware.BasicAuth(
+					"metrics",
+					metrics.BasicAuth.CredentialsMap(),
+				))
+			}
+
+			r.Handle(string(metrics.Endpoint), promhttp.Handler())
+		})
+	}
+
 	router.Route("/api/v1", func(r chi.Router) {
 		r.Group(func(r chi.Router) {
 			r.Use(auth.Middleware(