don't use monitorID dimension if matching meta value

pkg/receiver/smartagentreceiver/converter/metrics.go

@@ -24,6 +24,10 @@ import (
 	"go.uber.org/zap"
 )
 
+const (
+	monitorIDDim = "monitorID"
+)
+
 var (
 	errUnsupportedMetricTypeTimestamp = fmt.Errorf("unsupported metric type timestamp")
 )
@@ -72,6 +76,15 @@ func setDataTypeAndPoints(datapoint *sfx.Datapoint, ms pmetric.MetricSlice, time
 		return fmt.Errorf("unsupported value type %T: %v", datapoint.Value, datapoint.Value)
 	}
 
+	// isolated collectd plugins will set the "monitorID" dimension. We need to
+	// delete this dimension if it matches the meta value to prevent high cardinality values
+	// (especially a concern with receiver creator that uses endpoint IDs).
+	if mmID, metaSet := datapoint.Meta[monitorIDDim]; metaSet {
+		if dmID, dimSet := datapoint.Dimensions[monitorIDDim]; dimSet && dmID == mmID {
+			delete(datapoint.Dimensions, monitorIDDim)
+		}
+	}
+
 	switch sfxMetricType {
 	case sfx.Gauge, sfx.Enum, sfx.Rate:
 		m = ms.AppendEmpty()

pkg/receiver/smartagentreceiver/converter/metrics_test.go

@@ -246,6 +246,32 @@ func TestDatapointsToPDataMetrics(t *testing.T) {
 			}(),
 			expectedMetrics: pdataMetrics(pmetric.MetricTypeGauge, 13, now),
 		},
+		{
+			name: "undesired monitorID dimension",
+			datapoints: func() []*sfx.Datapoint {
+				pt := sfxDatapoint()
+				pt.Meta = map[any]any{"monitorID": "undesired.value"}
+				pt.Dimensions["monitorID"] = "undesired.value"
+				return []*sfx.Datapoint{pt}
+			}(),
+			expectedMetrics: func() pmetric.Metrics {
+				return pdataMetrics(pmetric.MetricTypeGauge, 13, now)
+			}(),
+		},
+		{
+			name: "desired monitorID dimension",
+			datapoints: func() []*sfx.Datapoint {
+				pt := sfxDatapoint()
+				pt.Meta = map[any]any{"monitorID": "undesired.value"}
+				pt.Dimensions["monitorID"] = "desired.value"
+				return []*sfx.Datapoint{pt}
+			}(),
+			expectedMetrics: func() pmetric.Metrics {
+				md := pdataMetrics(pmetric.MetricTypeGauge, 13, now)
+				md.ResourceMetrics().At(0).ScopeMetrics().At(0).Metrics().At(0).Gauge().DataPoints().At(0).Attributes().PutStr("monitorID", "desired.value")
+				return md
+			}(),
+		},
 	}
 
 	for _, test := range tests {