elasticsearch.events.retried: Add retry dimension (#209)

This commit adds a new dimension to the `elasticsearch.events.retried`
metric called `greatest_retry`. It represents the greatest observed
retry count for a bulk request. This is useful to understand how many
times documents in a bulk request have been retried.

Signed-off-by: Marc Lopez Rubio <[email protected]>

appender.go

@@ -449,7 +449,9 @@ func (a *Appender) flush(ctx context.Context, bulkIndexer *BulkIndexer) error {
 	}
 	if resp.RetriedDocs > 0 {
 		// docs are scheduled to be retried but not yet failed due to retry limit
-		a.addCount(resp.RetriedDocs, nil, a.metrics.docsRetried)
+		a.addCount(resp.RetriedDocs, nil, a.metrics.docsRetried,
+			metric.WithAttributes(attribute.Int("greatest_retry", resp.GreatestRetry)),
+		)
 	}
 	if docsIndexed > 0 {
 		a.addCount(docsIndexed, &a.docsIndexed,

appender_test.go

@@ -329,7 +329,11 @@ loop:
 		case "elasticsearch.events.processed":
 			assertProcessedCounter(m, indexerAttrs)
 		case "elasticsearch.events.retried":
-			assertCounter(m, 1, indexerAttrs)
+			assertCounter(m, 1, attribute.NewSet(
+				attribute.String("a", "b"),
+				attribute.String("c", "d"),
+				attribute.Int("greatest_retry", 1),
+			))
 		case "elasticsearch.bulk_requests.available":
 			assertCounter(m, stats.AvailableBulkRequests, indexerAttrs)
 		case "elasticsearch.flushed.bytes":
@@ -1046,7 +1050,9 @@ func TestAppenderRetryDocument(t *testing.T) {
 			docappendertest.AssertOTelMetrics(t, rm.ScopeMetrics[0].Metrics, func(m metricdata.Metrics) {
 				switch m.Name {
 				case "elasticsearch.events.retried":
-					assertCounter(m, 5, *attribute.EmptySet())
+					assertCounter(m, 5, attribute.NewSet(
+						attribute.Int("greatest_retry", 1),
+					))
 				}
 			})
 			assert.Equal(t, int64(1), asserted.Load())
@@ -1064,7 +1070,9 @@ func TestAppenderRetryDocument(t *testing.T) {
 			docappendertest.AssertOTelMetrics(t, rm.ScopeMetrics[0].Metrics, func(m metricdata.Metrics) {
 				switch m.Name {
 				case "elasticsearch.events.retried":
-					assertCounter(m, 5, *attribute.EmptySet())
+					assertCounter(m, 5, attribute.NewSet(
+						attribute.Int("greatest_retry", 2),
+					))
 				}
 			})
 			assert.Equal(t, int64(2), asserted.Load())

bulk_indexer.go

@@ -101,9 +101,15 @@ type BulkIndexer struct {
 }
 
 type BulkIndexerResponseStat struct {
-	Indexed     int64
+	// Indexed contains the total number of successfully indexed documents.
+	Indexed int64
+	// RetriedDocs contains the total number of retried documents.
 	RetriedDocs int64
-	FailedDocs  []BulkIndexerResponseItem
+	// GreatestRetry contains the greatest observed retry count in the entire
+	// bulk request.
+	GreatestRetry int
+	// FailedDocs contains the failed documents.
+	FailedDocs []BulkIndexerResponseItem
 }
 
 // BulkIndexerResponseItem represents the Elasticsearch response item.
@@ -483,6 +489,9 @@ func (b *BulkIndexer) Flush(ctx context.Context) (BulkIndexerResponseStat, error
 					tmp = append(tmp, res)
 					continue
 				}
+				if resp.GreatestRetry < count {
+					resp.GreatestRetry = count
+				}
 
 				// Since some items may have succeeded, counter positions need
 				// to be updated to match the next current buffer position.