Add line protocol uint64 support (#3946)

plugins/serializers/influx/influx.go

@@ -237,6 +237,8 @@ func (s *Serializer) writeMetric(w io.Writer, m telegraf.Metric) error {
 
 func appendFieldValue(buf []byte, value interface{}) ([]byte, error) {
 	switch v := value.(type) {
+	case uint64:
+		return appendUintField(buf, v), nil
 	case int64:
 		return appendIntField(buf, v), nil
 	case float64:
@@ -257,6 +259,10 @@ func appendFieldValue(buf []byte, value interface{}) ([]byte, error) {
 	return buf, ErrInvalidFieldType
 }
 
+func appendUintField(buf []byte, value uint64) []byte {
+	return append(strconv.AppendUint(buf, value, 10), 'u')
+}
+
 func appendIntField(buf []byte, value int64) []byte {
 	return append(strconv.AppendInt(buf, value, 10), 'i')
 }

plugins/serializers/influx/influx_test.go

@@ -11,12 +11,20 @@ import (
 )
 
 func MustMetric(v telegraf.Metric, err error) telegraf.Metric {
+	// Force uint support to be enabled for testing.
+	metric.EnableUintSupport()
 	if err != nil {
 		panic(err)
 	}
 	return v
 }
 
+const (
+	Uint64Overflow uint64 = 9223372036854775808
+	Uint64Max      uint64 = 18446744073709551615
+	Uint64Test     uint64 = 42
+)
+
 var tests = []struct {
 	name     string
 	maxBytes int
@@ -128,6 +136,48 @@ var tests = []struct {
 		),
 		output: []byte("cpu value=42i 0\n"),
 	},
+	{
+		name: "uint field",
+		input: MustMetric(
+			metric.New(
+				"cpu",
+				map[string]string{},
+				map[string]interface{}{
+					"value": Uint64Test,
+				},
+				time.Unix(0, 0),
+			),
+		),
+		output: []byte("cpu value=42u 0\n"),
+	},
+	{
+		name: "uint field int64 overflow",
+		input: MustMetric(
+			metric.New(
+				"cpu",
+				map[string]string{},
+				map[string]interface{}{
+					"value": Uint64Overflow,
+				},
+				time.Unix(0, 0),
+			),
+		),
+		output: []byte("cpu value=9223372036854775808u 0\n"),
+	},
+	{
+		name: "uint field uint64 max",
+		input: MustMetric(
+			metric.New(
+				"cpu",
+				map[string]string{},
+				map[string]interface{}{
+					"value": Uint64Max,
+				},
+				time.Unix(0, 0),
+			),
+		),
+		output: []byte("cpu value=18446744073709551615u 0\n"),
+	},
 	{
 		name: "bool field",
 		input: MustMetric(