feat: add /metrics endpoint handler for Prometheus monitoring (#269)

On-behalf-of: @SAP [email protected]

Signed-off-by: Angel Kafazov <[email protected]>

Author: akafazov

cmd/gateway.go

@@ -10,6 +10,7 @@ import (
 	openmfpcontext "github.com/openmfp/golang-commons/context"
 	"github.com/openmfp/golang-commons/sentry"
 	"github.com/openmfp/golang-commons/traces"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/spf13/cobra"
 	ctrl "sigs.k8s.io/controller-runtime"
 	restCfg "sigs.k8s.io/controller-runtime/pkg/client/config"
@@ -85,6 +86,9 @@ var gatewayCmd = &cobra.Command{
 		// Set up HTTP handler
 		http.Handle("/", managerInstance)
 
+		// Replace the /metrics endpoint handler
+		http.Handle("/metrics", promhttp.Handler())
+
 		// Start HTTP server with context
 		server := &http.Server{
 			Addr:    fmt.Sprintf(":%s", appCfg.Gateway.Port),