Fix bool serialization when using carbon2

plugins/serializers/carbon2/carbon2.go

@@ -57,7 +57,7 @@ func (s *Serializer) createObject(metric telegraf.Metric) []byte {
 	metricsFormat := s.getMetricsFormat()
 
 	for fieldName, fieldValue := range metric.Fields() {
-		if !isNumeric(fieldValue) {
+		if isString(fieldValue) {
 			continue
 		}
 
@@ -86,7 +86,7 @@ func (s *Serializer) createObject(metric telegraf.Metric) []byte {
 			m.WriteString(" ")
 		}
 		m.WriteString(" ")
-		m.WriteString(fmt.Sprintf("%v", fieldValue))
+		m.WriteString(formatValue(fieldValue))
 		m.WriteString(" ")
 		m.WriteString(strconv.FormatInt(metric.Time().Unix(), 10))
 		m.WriteString("\n")
@@ -126,11 +126,33 @@ func serializeMetricIncludeField(name, fieldName string) string {
 	)
 }
 
-func isNumeric(v interface{}) bool {
+func formatValue(fieldValue interface{}) string {
+	switch v := fieldValue.(type) {
+	case bool:
+		// Print bools as 0s and 1s
+		return fmt.Sprintf("%d", bool2int(v))
+	default:
+		return fmt.Sprintf("%v", v)
+	}
+}
+
+func isString(v interface{}) bool {
 	switch v.(type) {
 	case string:
-		return false
-	default:
 		return true
+	default:
+		return false
+	}
+}
+
+func bool2int(b bool) int {
+	// Slightly more optimized than a usual if ... return ... else return ... .
+	// See: https://0x0f.me/blog/golang-compiler-optimization/
+	var i int
+	if b {
+		i = 1
+	} else {
+		i = 0
 	}
+	return i
 }

plugins/serializers/carbon2/carbon2_test.go

@@ -209,6 +209,63 @@ func TestSerializeMetricString(t *testing.T) {
 	}
 }
 
+func TestSerializeMetricBool(t *testing.T) {
+	requireMetric := func(t *testing.T, tim time.Time, value bool) telegraf.Metric {
+		tags := map[string]string{
+			"tag_name": "tag_value",
+		}
+		fields := map[string]interface{}{
+			"java_lang_GarbageCollector_Valid": value,
+		}
+
+		m, err := metric.New("cpu", tags, fields, tim)
+		require.NoError(t, err)
+
+		return m
+	}
+
+	now := time.Now()
+
+	testcases := []struct {
+		metric   telegraf.Metric
+		format   string
+		expected string
+	}{
+		{
+			metric:   requireMetric(t, now, false),
+			format:   Carbon2FormatFieldSeparate,
+			expected: fmt.Sprintf("metric=cpu field=java_lang_GarbageCollector_Valid tag_name=tag_value  0 %d\n", now.Unix()),
+		},
+		{
+			metric:   requireMetric(t, now, false),
+			format:   Carbon2FormatMetricIncludesField,
+			expected: fmt.Sprintf("metric=cpu_java_lang_GarbageCollector_Valid tag_name=tag_value  0 %d\n", now.Unix()),
+		},
+		{
+			metric:   requireMetric(t, now, true),
+			format:   Carbon2FormatFieldSeparate,
+			expected: fmt.Sprintf("metric=cpu field=java_lang_GarbageCollector_Valid tag_name=tag_value  1 %d\n", now.Unix()),
+		},
+		{
+			metric:   requireMetric(t, now, true),
+			format:   Carbon2FormatMetricIncludesField,
+			expected: fmt.Sprintf("metric=cpu_java_lang_GarbageCollector_Valid tag_name=tag_value  1 %d\n", now.Unix()),
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.format, func(t *testing.T) {
+			s, err := NewSerializer(tc.format)
+			require.NoError(t, err)
+
+			buf, err := s.Serialize(tc.metric)
+			require.NoError(t, err)
+
+			assert.Equal(t, tc.expected, string(buf))
+		})
+	}
+}
+
 func TestSerializeBatch(t *testing.T) {
 	m := MustMetric(
 		metric.New(