added json serializer

closes #878

plugins/serializers/json/json.go

@@ -0,0 +1,27 @@
+package json
+
+import (
+	ejson "encoding/json"
+
+	"github.com/influxdata/telegraf"
+)
+
+type JsonSerializer struct {
+}
+
+func (s *JsonSerializer) Serialize(metric telegraf.Metric) ([]string, error) {
+	out := []string{}
+
+	m := make(map[string]interface{})
+	m["tags"] = metric.Tags()
+	m["fields"] = metric.Fields()
+	m["name"] = metric.Name()
+	m["timestamp"] = metric.UnixNano() / 1000000000
+	serialized, err := ejson.Marshal(m)
+	if err != nil {
+		return []string{}, err
+	}
+	out = append(out, string(serialized))
+
+	return out, nil
+}

plugins/serializers/json/json_test.go

@@ -0,0 +1,87 @@
+package json
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/influxdata/telegraf"
+)
+
+func TestSerializeMetricFloat(t *testing.T) {
+	now := time.Now()
+	tags := map[string]string{
+		"cpu": "cpu0",
+	}
+	fields := map[string]interface{}{
+		"usage_idle": float64(91.5),
+	}
+	m, err := telegraf.NewMetric("cpu", tags, fields, now)
+	assert.NoError(t, err)
+
+	s := JsonSerializer{}
+	mS, err := s.Serialize(m)
+	assert.NoError(t, err)
+	expS := []string{fmt.Sprintf("{\"fields\":{\"usage_idle\":91.5},\"name\":\"cpu\",\"tags\":{\"cpu\":\"cpu0\"},\"timestamp\":%d}", now.Unix())}
+	assert.Equal(t, expS, mS)
+}
+
+func TestSerializeMetricInt(t *testing.T) {
+	now := time.Now()
+	tags := map[string]string{
+		"cpu": "cpu0",
+	}
+	fields := map[string]interface{}{
+		"usage_idle": int64(90),
+	}
+	m, err := telegraf.NewMetric("cpu", tags, fields, now)
+	assert.NoError(t, err)
+
+	s := JsonSerializer{}
+	mS, err := s.Serialize(m)
+	assert.NoError(t, err)
+
+	expS := []string{fmt.Sprintf("{\"fields\":{\"usage_idle\":90},\"name\":\"cpu\",\"tags\":{\"cpu\":\"cpu0\"},\"timestamp\":%d}", now.Unix())}
+	assert.Equal(t, expS, mS)
+}
+
+func TestSerializeMetricString(t *testing.T) {
+	now := time.Now()
+	tags := map[string]string{
+		"cpu": "cpu0",
+	}
+	fields := map[string]interface{}{
+		"usage_idle": "foobar",
+	}
+	m, err := telegraf.NewMetric("cpu", tags, fields, now)
+	assert.NoError(t, err)
+
+	s := JsonSerializer{}
+	mS, err := s.Serialize(m)
+	assert.NoError(t, err)
+
+	expS := []string{fmt.Sprintf("{\"fields\":{\"usage_idle\":\"foobar\"},\"name\":\"cpu\",\"tags\":{\"cpu\":\"cpu0\"},\"timestamp\":%d}", now.Unix())}
+	assert.Equal(t, expS, mS)
+}
+
+func TestSerializeMultiFields(t *testing.T) {
+	now := time.Now()
+	tags := map[string]string{
+		"cpu": "cpu0",
+	}
+	fields := map[string]interface{}{
+		"usage_idle":  int64(90),
+		"usage_total": 8559615,
+	}
+	m, err := telegraf.NewMetric("cpu", tags, fields, now)
+	assert.NoError(t, err)
+
+	s := JsonSerializer{}
+	mS, err := s.Serialize(m)
+	assert.NoError(t, err)
+
+	expS := []string{fmt.Sprintf("{\"fields\":{\"usage_idle\":90,\"usage_total\":8559615},\"name\":\"cpu\",\"tags\":{\"cpu\":\"cpu0\"},\"timestamp\":%d}", now.Unix())}
+	assert.Equal(t, expS, mS)
+}

plugins/serializers/registry.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/influxdata/telegraf/plugins/serializers/graphite"
 	"github.com/influxdata/telegraf/plugins/serializers/influx"
+	"github.com/influxdata/telegraf/plugins/serializers/json"
 )
 
 // SerializerOutput is an interface for output plugins that are able to
@@ -40,10 +41,16 @@ func NewSerializer(config *Config) (Serializer, error) {
 		serializer, err = NewInfluxSerializer()
 	case "graphite":
 		serializer, err = NewGraphiteSerializer(config.Prefix)
+	case "json":
+		serializer, err = NewJsonSerializer()
 	}
 	return serializer, err
 }
 
+func NewJsonSerializer() (Serializer, error) {
+	return &json.JsonSerializer{}, nil
+}
+
 func NewInfluxSerializer() (Serializer, error) {
 	return &influx.InfluxSerializer{}, nil
 }