feat(inputs.kafka_consumer): Allow to select the metric time source

plugins/inputs/kafka_consumer/README.md

@@ -70,6 +70,13 @@ to use them.
   ## option, it will be excluded from the msg_headers_as_tags list.
   # msg_header_as_metric_name = ""
 
+  ## Set metric(s) timestamp using the given source.
+  ## Available options are:
+  ##   metric -- do not modify the metric timestamp
+  ##   inner  -- use the inner message timestamp (Kafka v0.10+)
+  ##   outer  -- use the outer (compressed) block timestamp (Kafka v0.10+)
+  # timestamp_source = "metric"
+
   ## Optional Client id
   # client_id = "Telegraf"
 

plugins/inputs/kafka_consumer/kafka_consumer.go

@@ -49,6 +49,7 @@ type KafkaConsumer struct {
 	TopicTag                             string          `toml:"topic_tag"`
 	MsgHeadersAsTags                     []string        `toml:"msg_headers_as_tags"`
 	MsgHeaderAsMetricName                string          `toml:"msg_header_as_metric_name"`
+	TimestampSource                      string          `toml:"timestamp_source"`
 	ConsumerFetchDefault                 config.Size     `toml:"consumer_fetch_default"`
 	ConnectionStrategy                   string          `toml:"connection_strategy"`
 	ResolveCanonicalBootstrapServersOnly bool            `toml:"resolve_canonical_bootstrap_servers_only"`
@@ -108,6 +109,14 @@ func (k *KafkaConsumer) Init() error {
 		k.ConsumerGroup = defaultConsumerGroup
 	}
 
+	switch k.TimestampSource {
+	case "":
+		k.TimestampSource = "metric"
+	case "metric", "inner", "outer":
+	default:
+		return fmt.Errorf("invalid timestamp source %q", k.TimestampSource)
+	}
+
 	cfg := sarama.NewConfig()
 
 	// Kafka version 0.10.2.0 is required for consumer groups.
@@ -334,6 +343,7 @@ func (k *KafkaConsumer) Start(acc telegraf.Accumulator) error {
 				}
 			}
 			handler.MsgHeadersToTags = msgHeadersMap
+			handler.TimestampSource = k.TimestampSource
 
 			// We need to copy allWantedTopics; the Consume() is
 			// long-running and we can easily deadlock if our
@@ -399,6 +409,7 @@ type ConsumerGroupHandler struct {
 	TopicTag              string
 	MsgHeadersToTags      map[string]bool
 	MsgHeaderToMetricName string
+	TimestampSource       string
 
 	acc    telegraf.TrackingAccumulator
 	sem    semaphore
@@ -495,12 +506,11 @@ func (h *ConsumerGroupHandler) Handle(session sarama.ConsumerGroupSession, msg *
 		})
 	}
 
-	headerKey := ""
 	// Check if any message header should override metric name or should be pass as tag
 	if len(h.MsgHeadersToTags) > 0 || h.MsgHeaderToMetricName != "" {
 		for _, header := range msg.Headers {
 			//convert to a string as the header and value are byte arrays.
-			headerKey = string(header.Key)
+			headerKey := string(header.Key)
 			if _, exists := h.MsgHeadersToTags[headerKey]; exists {
 				// If message header should be pass as tag then add it to the metrics
 				for _, metric := range metrics {
@@ -523,6 +533,18 @@ func (h *ConsumerGroupHandler) Handle(session sarama.ConsumerGroupSession, msg *
 		}
 	}
 
+	// Do override the metric timestamp if required
+	switch h.TimestampSource {
+	case "inner":
+		for _, metric := range metrics {
+			metric.SetTime(msg.Timestamp)
+		}
+	case "outer":
+		for _, metric := range metrics {
+			metric.SetTime(msg.BlockTimestamp)
+		}
+	}
+
 	h.mu.Lock()
 	id := h.acc.AddTrackingMetricGroup(metrics)
 	h.undelivered[id] = Message{session: session, message: msg}

plugins/inputs/kafka_consumer/kafka_consumer_test.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/config"
+	"github.com/influxdata/telegraf/metric"
 	"github.com/influxdata/telegraf/plugins/common/kafka"
 	"github.com/influxdata/telegraf/plugins/common/tls"
 	"github.com/influxdata/telegraf/plugins/outputs"
@@ -549,6 +550,81 @@ func TestKafkaRoundTripIntegration(t *testing.T) {
 	}
 }
 
+func TestKafkaTimestampSourceIntegration(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping integration test in short mode")
+	}
+
+	metrics := []telegraf.Metric{
+		metric.New(
+			"test",
+			map[string]string{},
+			map[string]interface{}{"value": 42},
+			time.Unix(1704067200, 0),
+		),
+	}
+
+	for _, source := range []string{"metric", "inner", "outer"} {
+		t.Run(source, func(t *testing.T) {
+			ctx := context.Background()
+			kafkaContainer, err := kafkacontainer.Run(ctx, "confluentinc/confluent-local:7.5.0")
+			require.NoError(t, err)
+			defer kafkaContainer.Terminate(ctx) //nolint:errcheck // ignored
+
+			brokers, err := kafkaContainer.Brokers(ctx)
+			require.NoError(t, err)
+
+			// Make kafka output
+			creator := outputs.Outputs["kafka"]
+			output, ok := creator().(*kafkaOutput.Kafka)
+			require.True(t, ok)
+
+			s := &influxSerializer.Serializer{}
+			require.NoError(t, s.Init())
+			output.SetSerializer(s)
+			output.Brokers = brokers
+			output.Topic = "Test"
+			output.Log = &testutil.Logger{}
+
+			require.NoError(t, output.Init())
+			require.NoError(t, output.Connect())
+			defer output.Close()
+
+			// Make kafka input
+			input := KafkaConsumer{
+				Brokers:                brokers,
+				Log:                    testutil.Logger{},
+				Topics:                 []string{"Test"},
+				MaxUndeliveredMessages: 1,
+			}
+			parser := &influx.Parser{}
+			require.NoError(t, parser.Init())
+			input.SetParser(parser)
+			require.NoError(t, input.Init())
+
+			var acc testutil.Accumulator
+			require.NoError(t, input.Start(&acc))
+			defer input.Stop()
+
+			// Send the metrics and check that we got it back
+			sendTimestamp := time.Now().Unix()
+			require.NoError(t, output.Write(metrics))
+			require.Eventually(t, func() bool { return acc.NMetrics() > 0 }, 5*time.Second, 100*time.Millisecond)
+			actual := acc.GetTelegrafMetrics()
+			testutil.RequireMetricsEqual(t, metrics, actual, testutil.IgnoreTime())
+
+			// Check the timestamp
+			m := actual[0]
+			switch source {
+			case "metric":
+				require.EqualValues(t, 1704067200, m.Time().Unix())
+			case "inner", "outer":
+				require.GreaterOrEqual(t, sendTimestamp, m.Time().Unix())
+			}
+		})
+	}
+}
+
 func TestExponentialBackoff(t *testing.T) {
 	var err error
 

plugins/inputs/kafka_consumer/sample.conf

@@ -33,6 +33,13 @@
   ## option, it will be excluded from the msg_headers_as_tags list.
   # msg_header_as_metric_name = ""
 
+  ## Set metric(s) timestamp using the given source.
+  ## Available options are:
+  ##   metric -- do not modify the metric timestamp
+  ##   inner  -- use the inner message timestamp (Kafka v0.10+)
+  ##   outer  -- use the outer (compressed) block timestamp (Kafka v0.10+)
+  # timestamp_source = "metric"
+
   ## Optional Client id
   # client_id = "Telegraf"