config: add support for with_resource_constant_labels option

This provides users the ability to apply labels for resource attributes to prometheus exported metrics.

Signed-off-by: Alex Boten <223565+codeboten@users.noreply.github.com>

config/metric.go

@@ -230,6 +230,22 @@ func prometheusReader(ctx context.Context, prometheusConfig *Prometheus) (sdkmet
 	if prometheusConfig.WithoutUnits != nil && *prometheusConfig.WithoutUnits {
 		opts = append(opts, otelprom.WithoutUnits())
 	}
+	if prometheusConfig.WithResourceConstantLabels != nil {
+		if prometheusConfig.WithResourceConstantLabels.Included != nil {
+			var keys []attribute.Key
+			for _, val := range prometheusConfig.WithResourceConstantLabels.Included {
+				keys = append(keys, attribute.Key(val))
+			}
+			otelprom.WithResourceAsConstantLabels(attribute.NewAllowKeysFilter(keys...))
+		}
+		if prometheusConfig.WithResourceConstantLabels.Excluded != nil {
+			var keys []attribute.Key
+			for _, val := range prometheusConfig.WithResourceConstantLabels.Included {
+				keys = append(keys, attribute.Key(val))
+			}
+			otelprom.WithResourceAsConstantLabels(attribute.NewDenyKeysFilter(keys...))
+		}
+	}
 
 	reg := prometheus.NewRegistry()
 	opts = append(opts, otelprom.WithRegisterer(reg))
@@ -246,9 +262,6 @@ func prometheusReader(ctx context.Context, prometheusConfig *Prometheus) (sdkmet
 	}
 	addr := fmt.Sprintf("%s:%d", *prometheusConfig.Host, *prometheusConfig.Port)
 
-	// TODO: add support for constant label filter
-	// 	otelprom.WithResourceAsConstantLabels(attribute.NewDenyKeysFilter()),
-	// )
 	reader, err := otelprom.New(opts...)
 	if err != nil {
 		return nil, fmt.Errorf("error creating otel prometheus exporter: %w", err)

config/metric_test.go

@@ -148,8 +148,15 @@ func TestReader(t *testing.T) {
 				Pull: &PullMetricReader{
 					Exporter: MetricExporter{
 						Prometheus: &Prometheus{
-							Host: ptr("localhost"),
-							Port: ptr(8888),
+							Host:              ptr("localhost"),
+							Port:              ptr(8888),
+							WithoutScopeInfo:  ptr(true),
+							WithoutUnits:      ptr(true),
+							WithoutTypeSuffix: ptr(true),
+							WithResourceConstantLabels: &IncludeExclude{
+								Included: []string{"include"},
+								Excluded: []string{"exclude"},
+							},
 						},
 					},
 				},