diff --git a/pkg/extensions/monitoring/common.go b/pkg/extensions/monitoring/common.go
index a31fca56..3636ed8e 100644
--- a/pkg/extensions/monitoring/common.go
+++ b/pkg/extensions/monitoring/common.go
@@ -1,7 +1,6 @@
 package monitoring
 
 import (
-	"fmt"
 	"os"
 	"path/filepath"
 )
@@ -28,5 +27,5 @@ func getDirSize(path string) (int64, error) {
 		return err
 	})
 
-	return size, fmt.Errorf("getDirSize: %w", err)
+	return size, err
 }
diff --git a/pkg/extensions/monitoring/monitoring_test.go b/pkg/extensions/monitoring/monitoring_test.go
new file mode 100644
index 00000000..edaa6ce6
--- /dev/null
+++ b/pkg/extensions/monitoring/monitoring_test.go
@@ -0,0 +1,126 @@
+//go:build extended
+// +build extended
+
+package monitoring_test
+
+import (
+	"context"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"path"
+	"testing"
+	"time"
+
+	. "github.com/smartystreets/goconvey/convey"
+	"gopkg.in/resty.v1"
+	"zotregistry.io/zot/pkg/api"
+	"zotregistry.io/zot/pkg/api/config"
+	extconf "zotregistry.io/zot/pkg/extensions/config"
+	"zotregistry.io/zot/pkg/extensions/monitoring"
+	. "zotregistry.io/zot/test"
+)
+
+func TestExtensionMetrics(t *testing.T) {
+	Convey("Make a new controller with explicitly enabled metrics", t, func() {
+		port := GetFreePort()
+		baseURL := GetBaseURL(port)
+		conf := config.New()
+		conf.HTTP.Port = port
+
+		rootDir, err := ioutil.TempDir("", "metrics-test")
+		if err != nil {
+			panic(err)
+		}
+		defer os.RemoveAll(rootDir)
+
+		conf.Storage.RootDirectory = rootDir
+		conf.Extensions = &extconf.ExtensionConfig{}
+		conf.Extensions.Metrics = &extconf.MetricsConfig{
+			Enable:     true,
+			Prometheus: &extconf.PrometheusConfig{Path: "/metrics"},
+		}
+
+		ctlr := api.NewController(conf)
+		So(ctlr, ShouldNotBeNil)
+
+		go startServer(ctlr)
+		defer stopServer(ctlr)
+		WaitTillServerReady(baseURL)
+
+		// improve code coverage
+		ctlr.Metrics.SendMetric(baseURL)
+		ctlr.Metrics.ForceSendMetric(baseURL)
+
+		So(ctlr.Metrics.IsEnabled(), ShouldBeTrue)
+		So(ctlr.Metrics.ReceiveMetrics(), ShouldBeNil)
+
+		monitoring.ObserveHTTPRepoLatency(ctlr.Metrics,
+			"/v2/alpine/blobs/uploads/299148f0-0e32-4830-90d2-a3fa744137d9", time.Millisecond)
+		monitoring.IncDownloadCounter(ctlr.Metrics, "alpine")
+		monitoring.IncUploadCounter(ctlr.Metrics, "alpine")
+
+		err = CopyFiles("../../../test/data/zot-test", path.Join(rootDir, "alpine"))
+		if err != nil {
+			panic(err)
+		}
+		monitoring.SetStorageUsage(ctlr.Metrics, rootDir, "alpine")
+
+		monitoring.ObserveStorageLockLatency(ctlr.Metrics, time.Millisecond, rootDir, "RWLock")
+
+		resp, err := resty.R().Get(baseURL + "/metrics")
+		So(err, ShouldBeNil)
+		So(resp, ShouldNotBeNil)
+		So(resp.StatusCode(), ShouldEqual, http.StatusOK)
+
+		respStr := string(resp.Body())
+		So(respStr, ShouldContainSubstring, "zot_repo_downloads_total{repo=\"alpine\"} 1")
+		So(respStr, ShouldContainSubstring, "zot_repo_uploads_total{repo=\"alpine\"} 1")
+		So(respStr, ShouldContainSubstring, "zot_repo_storage_bytes{repo=\"alpine\"}")
+		So(respStr, ShouldContainSubstring, "zot_storage_lock_latency_seconds_bucket")
+		So(respStr, ShouldContainSubstring, "zot_storage_lock_latency_seconds_sum")
+		So(respStr, ShouldContainSubstring, "zot_storage_lock_latency_seconds_bucket")
+	})
+	Convey("Make a new controller with disabled metrics extension", t, func() {
+		port := GetFreePort()
+		baseURL := GetBaseURL(port)
+		conf := config.New()
+		conf.HTTP.Port = port
+
+		rootDir, err := ioutil.TempDir("", "metrics-test")
+		if err != nil {
+			panic(err)
+		}
+		defer os.RemoveAll(rootDir)
+
+		conf.Storage.RootDirectory = rootDir
+		conf.Extensions = &extconf.ExtensionConfig{}
+		conf.Extensions.Metrics = &extconf.MetricsConfig{Enable: false}
+
+		ctlr := api.NewController(conf)
+		So(ctlr, ShouldNotBeNil)
+
+		go startServer(ctlr)
+		defer stopServer(ctlr)
+		WaitTillServerReady(baseURL)
+
+		So(ctlr.Metrics.IsEnabled(), ShouldBeFalse)
+
+		resp, err := resty.R().Get(baseURL + "/metrics")
+		So(err, ShouldBeNil)
+		So(resp, ShouldNotBeNil)
+		So(resp.StatusCode(), ShouldEqual, http.StatusNotFound)
+	})
+}
+
+func startServer(c *api.Controller) {
+	// this blocks
+	if err := c.Run(); err != nil {
+		return
+	}
+}
+
+func stopServer(c *api.Controller) {
+	ctx := context.Background()
+	_ = c.Server.Shutdown(ctx)
+}