From 3dbe261cb24ead17dc7f01d811a467b067183fa8 Mon Sep 17 00:00:00 2001
From: Salva Corts <salva.corts@grafana.com>
Date: Mon, 16 Oct 2023 11:34:25 +0200
Subject: [PATCH] loki.process: enable structured_metadata labels conversion
 (loki/#10752) (#5481)

---
 CHANGELOG.md                                  |  3 ++
 .../process/stages/structured_metadata.go     | 22 ++++++++++++-
 .../stages/structured_metadata_test.go        | 32 +++++++++++++++++++
 3 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ffebace935a1..d5163a871356 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -42,6 +42,9 @@ Main (unreleased)
 
 - Update Prometheus dependency to v2.47.2. (@tpaschalis)
 
+- Allow converting labels to structured metadata with Loki's structured_metadata stage. (@gonzalesraul)
+
+
 v0.37.1 (2023-10-10)
 -----------------
 
diff --git a/component/loki/process/stages/structured_metadata.go b/component/loki/process/stages/structured_metadata.go
index 2c752ac5017c..abaee55245b8 100644
--- a/component/loki/process/stages/structured_metadata.go
+++ b/component/loki/process/stages/structured_metadata.go
@@ -32,6 +32,26 @@ func (s *structuredMetadataStage) Run(in chan Entry) chan Entry {
 		processLabelsConfigs(s.logger, e.Extracted, s.cfgs, func(labelName model.LabelName, labelValue model.LabelValue) {
 			e.StructuredMetadata = append(e.StructuredMetadata, logproto.LabelAdapter{Name: string(labelName), Value: string(labelValue)})
 		})
-		return e
+		return s.extractFromLabels(e)
 	})
 }
+
+func (s *structuredMetadataStage) extractFromLabels(e Entry) Entry {
+	labels := e.Labels
+	foundLabels := []model.LabelName{}
+
+	for lName, lSrc := range s.cfgs.Values {
+		labelKey := model.LabelName(*lSrc)
+		if lValue, ok := labels[labelKey]; ok {
+			e.StructuredMetadata = append(e.StructuredMetadata, logproto.LabelAdapter{Name: lName, Value: string(lValue)})
+			foundLabels = append(foundLabels, labelKey)
+		}
+	}
+
+	// Remove found labels, do this after append to structure metadata
+	for _, fl := range foundLabels {
+		delete(labels, fl)
+	}
+	e.Labels = labels
+	return e
+}
diff --git a/component/loki/process/stages/structured_metadata_test.go b/component/loki/process/stages/structured_metadata_test.go
index e5a858584872..33a62fe25f69 100644
--- a/component/loki/process/stages/structured_metadata_test.go
+++ b/component/loki/process/stages/structured_metadata_test.go
@@ -71,6 +71,26 @@ stage.labels {
 }
 `
 
+var pipelineStagesStructuredMetadataFromStaticLabels = `
+stage.static_labels {
+	values = {"component" = "querier", "pod" = "loki-querier-664f97db8d-qhnwg"}
+}
+
+stage.structured_metadata {
+	values = {"pod" = ""}
+}
+`
+
+var pipelineStagesStructuredMetadataFromStaticLabelsDifferentKey = `
+stage.static_labels {
+	values = {"component" = "querier", "pod" = "loki-querier-664f97db8d-qhnwg"}
+}
+
+stage.structured_metadata {
+	values = {"pod_name" = "pod"}
+}
+`
+
 func Test_StructuredMetadataStage(t *testing.T) {
 	tests := map[string]struct {
 		pipelineStagesYaml         string
@@ -104,6 +124,18 @@ func Test_StructuredMetadataStage(t *testing.T) {
 			expectedStructuredMetadata: push.LabelsAdapter{push.LabelAdapter{Name: "app", Value: "loki"}},
 			expectedLabels:             model.LabelSet{model.LabelName("component"): model.LabelValue("ingester")},
 		},
+		"expected structured metadata and regular labels to be extracted with static labels stage and to be added to entry": {
+			pipelineStagesYaml:         pipelineStagesStructuredMetadataFromStaticLabels,
+			logLine:                    `sample log line`,
+			expectedStructuredMetadata: push.LabelsAdapter{push.LabelAdapter{Name: "pod", Value: "loki-querier-664f97db8d-qhnwg"}},
+			expectedLabels:             model.LabelSet{model.LabelName("component"): model.LabelValue("querier")},
+		},
+		"expected structured metadata and regular labels to be extracted with static labels stage using different structured key": {
+			pipelineStagesYaml:         pipelineStagesStructuredMetadataFromStaticLabelsDifferentKey,
+			logLine:                    `sample log line`,
+			expectedStructuredMetadata: push.LabelsAdapter{push.LabelAdapter{Name: "pod_name", Value: "loki-querier-664f97db8d-qhnwg"}},
+			expectedLabels:             model.LabelSet{model.LabelName("component"): model.LabelValue("querier")},
+		},
 	}
 	for name, test := range tests {
 		t.Run(name, func(t *testing.T) {