From 8d1bf60bce18acecf64d2f29bd5ace9239f94c7e Mon Sep 17 00:00:00 2001
From: Sven Rebhan <36194019+srebhan@users.noreply.github.com>
Date: Mon, 23 Oct 2023 15:47:55 +0200
Subject: [PATCH] fix(serializers.json): Append newline for batch-serialization
 (#14150)

---
 plugins/serializers/json/json.go      | 2 ++
 plugins/serializers/json/json_test.go | 6 +++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/plugins/serializers/json/json.go b/plugins/serializers/json/json.go
index 8a90e5605..3923aec96 100644
--- a/plugins/serializers/json/json.go
+++ b/plugins/serializers/json/json.go
@@ -103,6 +103,8 @@ func (s *Serializer) SerializeBatch(metrics []telegraf.Metric) ([]byte, error) {
 	if err != nil {
 		return []byte{}, err
 	}
+	serialized = append(serialized, '\n')
+
 	return serialized, nil
 }
 
diff --git a/plugins/serializers/json/json_test.go b/plugins/serializers/json/json_test.go
index 3c7894903..34ea8dea6 100644
--- a/plugins/serializers/json/json_test.go
+++ b/plugins/serializers/json/json_test.go
@@ -197,7 +197,7 @@ func TestSerializeBatch(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(
 		t,
-		[]byte(`{"metrics":[{"fields":{"value":42},"name":"cpu","tags":{},"timestamp":0},{"fields":{"value":42},"name":"cpu","tags":{},"timestamp":0}]}`),
+		[]byte(`{"metrics":[{"fields":{"value":42},"name":"cpu","tags":{},"timestamp":0},{"fields":{"value":42},"name":"cpu","tags":{},"timestamp":0}]}`+"\n"),
 		buf,
 	)
 }
@@ -219,7 +219,7 @@ func TestSerializeBatchSkipInf(t *testing.T) {
 	require.NoError(t, s.Init())
 	buf, err := s.SerializeBatch(metrics)
 	require.NoError(t, err)
-	require.Equal(t, []byte(`{"metrics":[{"fields":{"time_idle":42},"name":"cpu","tags":{},"timestamp":0}]}`), buf)
+	require.Equal(t, []byte(`{"metrics":[{"fields":{"time_idle":42},"name":"cpu","tags":{},"timestamp":0}]}`+"\n"), buf)
 }
 
 func TestSerializeBatchSkipInfAllFields(t *testing.T) {
@@ -238,7 +238,7 @@ func TestSerializeBatchSkipInfAllFields(t *testing.T) {
 	require.NoError(t, s.Init())
 	buf, err := s.SerializeBatch(metrics)
 	require.NoError(t, err)
-	require.Equal(t, []byte(`{"metrics":[{"fields":{},"name":"cpu","tags":{},"timestamp":0}]}`), buf)
+	require.Equal(t, []byte(`{"metrics":[{"fields":{},"name":"cpu","tags":{},"timestamp":0}]}`+"\n"), buf)
 }
 
 func TestSerializeTransformationNonBatch(t *testing.T) {