Support for namespace in grpc prometheus counter and histogram metrics (#718)

* Support for namespace in grpc prometheus counter and histogram metrics

* Update providers/prometheus/options.go

Co-authored-by: Johan Brandhorst-Satzkorn <[email protected]>

---------

Co-authored-by: Johan Brandhorst-Satzkorn <[email protected]>

Author: hyungi

providers/prometheus/client_test.go

@@ -114,3 +114,17 @@ func (s *ClientInterceptorTestSuite) TestWithSubsystem() {
 	requireSubsystemName(s.T(), "subsystem1", clientMetrics.clientStartedCounter.WithLabelValues("unary", testpb.TestServiceFullName, "dummy"))
 	requireHistSubsystemName(s.T(), "subsystem1", clientMetrics.clientHandledHistogram.WithLabelValues("unary", testpb.TestServiceFullName, "dummy"))
 }
+
+func (s *ClientInterceptorTestSuite) TestWithNamespace() {
+	counterOpts := []CounterOption{
+		WithNamespace("namespace1"),
+	}
+	histOpts := []HistogramOption{
+		WithHistogramNamespace("namespace1"),
+	}
+	clientCounterOpts := WithClientCounterOptions(counterOpts...)
+	clientMetrics := NewClientMetrics(clientCounterOpts, WithClientHandlingTimeHistogram(histOpts...))
+
+	requireNamespaceName(s.T(), "namespace1", clientMetrics.clientStartedCounter.WithLabelValues("unary", testpb.TestServiceFullName, "dummy"))
+	requireHistNamespaceName(s.T(), "namespace1", clientMetrics.clientHandledHistogram.WithLabelValues("unary", testpb.TestServiceFullName, "dummy"))
+}

providers/prometheus/options.go

@@ -46,6 +46,13 @@ func WithSubsystem(subsystem string) CounterOption {
 	}
 }
 
+// WithNamespace allows you to add a Namespace to Counter metrics.
+func WithNamespace(namespace string) CounterOption {
+	return func(o *prometheus.CounterOpts) {
+		o.Namespace = namespace
+	}
+}
+
 // A HistogramOption lets you add options to Histogram metrics using With*
 // funcs.
 type HistogramOption func(*prometheus.HistogramOpts)
@@ -95,6 +102,13 @@ func WithHistogramSubsystem(subsystem string) HistogramOption {
 	}
 }
 
+// WithHistogramNamespace allows you to add a Namespace to histograms metrics.
+func WithHistogramNamespace(namespace string) HistogramOption {
+	return func(o *prometheus.HistogramOpts) {
+		o.Namespace = namespace
+	}
+}
+
 func typeFromMethodInfo(mInfo *grpc.MethodInfo) grpcType {
 	if !mInfo.IsClientStream && !mInfo.IsServerStream {
 		return Unary

providers/prometheus/server_test.go

@@ -259,6 +259,18 @@ func requireSubsystemName(t *testing.T, expect string, c prometheus.Collector) {
 	t.Fail()
 }
 
+func requireNamespaceName(t *testing.T, expect string, c prometheus.Collector) {
+	t.Helper()
+	metricFullName := reflect.ValueOf(*c.(prometheus.Metric).Desc()).FieldByName("fqName").String()
+
+	if strings.Split(metricFullName, "_")[0] == expect {
+		return
+	}
+
+	t.Errorf("expected %s value to start with %s; ", metricFullName, expect)
+	t.Fail()
+}
+
 func requireValue(t *testing.T, expect int, c prometheus.Collector) {
 	t.Helper()
 	v := int(testutil.ToFloat64(c))
@@ -283,6 +295,18 @@ func requireHistSubsystemName(t *testing.T, expect string, o prometheus.Observer
 	t.Fail()
 }
 
+func requireHistNamespaceName(t *testing.T, expect string, o prometheus.Observer) {
+	t.Helper()
+	metricFullName := reflect.ValueOf(*o.(prometheus.Metric).Desc()).FieldByName("fqName").String()
+
+	if strings.Split(metricFullName, "_")[0] == expect {
+		return
+	}
+
+	t.Errorf("expected %s value to start with %s; ", metricFullName, expect)
+	t.Fail()
+}
+
 func requireValueHistCount(t *testing.T, expect int, o prometheus.Observer) {
 	t.Helper()
 	v := int(toFloat64HistCount(o))