feat(serializers.influx): Add option to omit timestamp

fixes: influxdata#15219

plugins/serializers/influx/README.md

@@ -30,6 +30,12 @@ for interoperability.
   ## integer values.  Enabling this option will result in field type errors if
   ## existing data has been written.
   influx_uint_support = false
+
+  ## When true, Telegraf will omit the timestamp on data to allow InfluxDB
+  ## to set the timestamp of the data during ingestion. This is generally NOT
+  ## what you want as it can lead to data points captured at different times
+  ## getting omitted due to similar data.
+  # influx_omit_timestamp = true
 ```
 
 ## Metrics

plugins/serializers/influx/influx.go

@@ -46,9 +46,10 @@ func (e FieldError) Error() string {
 
 // Serializer is a serializer for line protocol.
 type Serializer struct {
-	MaxLineBytes int  `toml:"influx_max_line_bytes"`
-	SortFields   bool `toml:"influx_sort_fields"`
-	UintSupport  bool `toml:"influx_uint_support"`
+	MaxLineBytes  int  `toml:"influx_max_line_bytes"`
+	SortFields    bool `toml:"influx_sort_fields"`
+	UintSupport   bool `toml:"influx_uint_support"`
+	OmitTimestamp bool `toml:"influx_omit_timestamp"`
 
 	bytesWritten int
 
@@ -153,8 +154,10 @@ func (s *Serializer) buildHeader(m telegraf.Metric) error {
 
 func (s *Serializer) buildFooter(m telegraf.Metric) {
 	s.footer = s.footer[:0]
-	s.footer = append(s.footer, ' ')
-	s.footer = strconv.AppendInt(s.footer, m.Time().UnixNano(), 10)
+	if !s.OmitTimestamp {
+		s.footer = append(s.footer, ' ')
+		s.footer = strconv.AppendInt(s.footer, m.Time().UnixNano(), 10)
+	}
 	s.footer = append(s.footer, '\n')
 }
 

plugins/serializers/influx/influx_test.go

@@ -497,6 +497,24 @@ func TestSerializer(t *testing.T) {
 	}
 }
 
+func TestOmitTimestamp(t *testing.T) {
+	m := metric.New(
+		"cpu",
+		map[string]string{},
+		map[string]interface{}{
+			"value": 42.0,
+		},
+		time.Unix(1519194109, 42),
+	)
+
+	serializer := &Serializer{
+		OmitTimestamp: true,
+	}
+	output, err := serializer.Serialize(m)
+	require.NoError(t, err)
+	require.Equal(t, []byte("cpu value=42\n"), output)
+}
+
 func BenchmarkSerializer(b *testing.B) {
 	for _, tt := range tests {
 		b.Run(tt.name, func(b *testing.B) {

plugins/serializers/registry.go

@@ -94,6 +94,9 @@ type Config struct {
 	// Support unsigned integer output; influx format only
 	InfluxUintSupport bool `toml:"influx_uint_support"`
 
+	// Omit timestamp from output; influx format only
+	InfluxOmitTimestamp bool `toml:"influx_omit_timestamp"`
+
 	// Prefix to add to all measurements, only supports Graphite
 	Prefix string `toml:"prefix"`