loki.source.api: fix a bug where structured metadata is not passed do…

…wnstream (#6508)

CHANGELOG.md

@@ -7,6 +7,13 @@ This document contains a historical list of changes between releases. Only
 changes that impact end-user behavior are listed; changes to documentation or
 internal API changes are not present.
 
+v0.40.3 (2024-03-14)
+--------------------
+
+### Bugfixes
+
+- Fix a bug where structured metadata and parsed field are not passed further in `loki.source.api` (@marchellodev)
+
 v0.40.2 (2024-03-05)
 --------------------
 

component/loki/source/api/internal/lokipush/push_api_server.go

@@ -185,7 +185,9 @@ func (s *PushAPIServer) handleLoki(w http.ResponseWriter, r *http.Request) {
 			e := loki.Entry{
 				Labels: filtered.Clone(),
 				Entry: logproto.Entry{
-					Line: entry.Line,
+					Line:               entry.Line,
+					StructuredMetadata: entry.StructuredMetadata,
+					Parsed:             entry.Parsed,
 				},
 			}
 			if keepTimestamp {

component/loki/source/api/internal/lokipush/push_api_server_test.go

@@ -23,6 +23,7 @@ import (
 	frelabel "github.com/grafana/agent/component/common/relabel"
 	"github.com/grafana/dskit/flagext"
 	"github.com/grafana/loki/pkg/logproto"
+	"github.com/grafana/loki/pkg/push"
 	"github.com/grafana/river"
 	"github.com/phayes/freeport"
 	"github.com/prometheus/client_golang/prometheus"
@@ -79,6 +80,10 @@ regex = "dropme"
 			Entry: logproto.Entry{
 				Timestamp: time.Unix(int64(i), 0),
 				Line:      "line" + strconv.Itoa(i),
+				StructuredMetadata: push.LabelsAdapter{
+					{Name: "i", Value: strconv.Itoa(i)},
+					{Name: "anotherMetaData", Value: "val"},
+				},
 			},
 		}
 	}
@@ -98,9 +103,18 @@ regex = "dropme"
 		"pushserver": "pushserver1",
 		"stream":     "stream1",
 	}
+
+	expectedStructuredMetadata := push.LabelsAdapter{
+		{Name: "i", Value: strconv.Itoa(0)},
+		{Name: "anotherMetaData", Value: "val"},
+	}
+
 	// Spot check the first value in the result to make sure relabel rules were applied properly
 	require.Equal(t, expectedLabels, eh.Received()[0].Labels)
 
+	// Spot check the first value in the result to make sure structured metadata was received properly
+	require.Equal(t, expectedStructuredMetadata, eh.Received()[0].StructuredMetadata)
+
 	// With keep timestamp enabled, verify timestamp
 	require.Equal(t, time.Unix(99, 0).Unix(), eh.Received()[99].Timestamp.Unix())