Fix: Skip SUMMARY and other unsupported metric types in ParsePrometheusMetrics

The OpenTelemetry Prometheus exporter exports additional metric types like
SUMMARY (e.g., go_gc_duration_seconds) that were not handled by the parser.
Instead of returning an error for unsupported types, we now skip them since
NPD only cares about its own COUNTER and GAUGE metrics.

Co-authored-by: MartinForReal <[email protected]>

Author: Copilot

pkg/util/metrics/helpers.go

@@ -66,6 +66,7 @@ func getAttributeKeysFromNames(tagNames []string) []attribute.Key {
 // ParsePrometheusMetrics parses Prometheus formatted metrics into metrics under Float64MetricRepresentation.
 //
 // Note: Prometheus's go library stores all counter/gauge-typed metric values under float64.
+// Note: Only COUNTER and GAUGE metric types are parsed. Other types (SUMMARY, HISTOGRAM, UNTYPED) are skipped.
 func ParsePrometheusMetrics(metricsText string) ([]Float64MetricRepresentation, error) {
 	var metrics []Float64MetricRepresentation
 
@@ -90,8 +91,9 @@ func ParsePrometheusMetrics(metricsText string) ([]Float64MetricRepresentation,
 			case pcm.MetricType_GAUGE:
 				value = *metric.Gauge.Value
 			default:
-				return metrics, fmt.Errorf("unexpected MetricType %s for metric %s",
-					pcm.MetricType_name[int32(*metricFamily.Type)], *metricFamily.Name)
+				// Skip unsupported metric types (SUMMARY, HISTOGRAM, UNTYPED, GAUGE_HISTOGRAM)
+				// These are typically Go runtime metrics and not NPD-specific metrics
+				continue
 			}
 
 			metrics = append(metrics, Float64MetricRepresentation{*metricFamily.Name, labels, value})