Put metric before label value in the "label value too long" error mes… (#4018)

* Put metric before label value in the "label value too long" error message (#1582)

Signed-off-by: ChinYing-Li <[email protected]>

Fix wrong message

* Fix the Pull Request number in CHANGELOG.md

Signed-off-by: ChinYing-Li <[email protected]>

Co-authored-by: Peter Štibraný <[email protected]>

Author: ChinYing-Li

CHANGELOG.md

@@ -21,6 +21,7 @@
 * [ENHANCEMENT] Querier / ruler: some optimizations to PromQL query engine. #3934 #3989
 * [ENHANCEMENT] Ingester: reduce CPU and memory when an high number of errors are returned by the ingester on the write path with the blocks storage. #3969 #3971 #3973
 * [ENHANCEMENT] Distributor: reduce CPU and memory when an high number of errors are returned by the distributor on the write path. #3990
+* [ENHANCEMENT] Put metric before label value in the "label value too long" error message. #4018
 * [BUGFIX] Ruler-API: fix bug where `/api/v1/rules/<namespace>/<group_name>` endpoint return `400` instead of `404`. #4013
 * [BUGFIX] Distributor: reverted changes done to rate limiting in #3825. #3948
 * [BUGFIX] Ingester: Fix race condition when opening and closing tsdb concurrently. #3959

pkg/util/validation/errors.go

@@ -34,11 +34,21 @@ func newLabelNameTooLongError(series []cortexpb.LabelAdapter, labelName string)
 	}
 }
 
+// labelValueTooLongError is a customized ValidationError, in that the cause and the series are
+// are formatted in different order in Error.
+type labelValueTooLongError struct {
+	labelValue string
+	series     []cortexpb.LabelAdapter
+}
+
+func (e *labelValueTooLongError) Error() string {
+	return fmt.Sprintf("label value too long for metric: %.200q label value: %.200q", formatLabelSet(e.series), e.labelValue)
+}
+
 func newLabelValueTooLongError(series []cortexpb.LabelAdapter, labelValue string) ValidationError {
-	return &genericValidationError{
-		message: "label value too long: %.200q metric %.200q",
-		cause:   labelValue,
-		series:  series,
+	return &labelValueTooLongError{
+		labelValue: labelValue,
+		series:     series,
 	}
 }