telegraf/outputs/librato/librato.go

package librato

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log"
	"net/http"

	"github.com/influxdb/influxdb/client/v2"
	"github.com/influxdb/telegraf/duration"
	"github.com/influxdb/telegraf/outputs"
)

type Librato struct {
	ApiUser   string
	ApiToken  string
	SourceTag string
	Timeout   duration.Duration

	apiUrl string
	client *http.Client
}

var sampleConfig = `
  # Librator API Docs
  # http://dev.librato.com/v1/metrics-authentication

  # Librato API user
  api_user = "telegraf@influxdb.com" # required.

  # Librato API token
  api_token = "my-secret-token" # required.

  # Tag Field to populate source attribute (optional)
  # This is typically the _hostname_ from which the metric was obtained.
  source_tag = "hostname"

  # Connection timeout.
  # timeout = "5s"
`

type Metrics struct {
	Gauges []*Gauge `json:"gauges"`
}

type Gauge struct {
	Name        string  `json:"name"`
	Value       float64 `json:"value"`
	Source      string  `json:"source"`
	MeasureTime int64   `json:"measure_time"`
}

const librato_api = "https://metrics-api.librato.com/v1/metrics"

func NewLibrato(apiUrl string) *Librato {
	return &Librato{
		apiUrl: apiUrl,
	}
}

func (l *Librato) Connect() error {
	if l.ApiUser == "" || l.ApiToken == "" {
		return fmt.Errorf("api_user and api_token are required fields for librato output")
	}
	l.client = &http.Client{
		Timeout: l.Timeout.Duration,
	}
	return nil
}

func (l *Librato) Write(points []*client.Point) error {
	if len(points) == 0 {
		return nil
	}
	metrics := Metrics{}
	var tempGauges = make([]*Gauge, len(points))
	var acceptablePoints = 0
	for _, pt := range points {
		if gauge, err := l.buildGauge(pt); err == nil {
			tempGauges[acceptablePoints] = gauge
			acceptablePoints += 1
		} else {
			log.Printf("unable to build Gauge for %s, skipping\n", pt.Name())
		}
	}
	metrics.Gauges = make([]*Gauge, acceptablePoints)
	copy(metrics.Gauges, tempGauges[0:])
	metricsBytes, err := json.Marshal(metrics)
	if err != nil {
		return fmt.Errorf("unable to marshal Metrics, %s\n", err.Error())
	}
	req, err := http.NewRequest("POST", l.apiUrl, bytes.NewBuffer(metricsBytes))
	if err != nil {
		return fmt.Errorf("unable to create http.Request, %s\n", err.Error())
	}
	req.Header.Add("Content-Type", "application/json")
	req.SetBasicAuth(l.ApiUser, l.ApiToken)

	resp, err := l.client.Do(req)
	if err != nil {
		return fmt.Errorf("error POSTing metrics, %s\n", err.Error())
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		return fmt.Errorf("received bad status code, %d\n", resp.StatusCode)
	}

	return nil
}

func (l *Librato) SampleConfig() string {
	return sampleConfig
}

func (l *Librato) Description() string {
	return "Configuration for Librato API to send metrics to."
}

func (l *Librato) buildGauge(pt *client.Point) (*Gauge, error) {
	gauge := &Gauge{
		Name:        pt.Name(),
		MeasureTime: pt.Time().Unix(),
	}
	if err := gauge.setValue(pt.Fields()["value"]); err != nil {
		return gauge, fmt.Errorf("unable to extract value from Fields, %s\n", err.Error())
	}
	if l.SourceTag != "" {
		if source, ok := pt.Tags()[l.SourceTag]; ok {
			gauge.Source = source
		} else {
			return gauge, fmt.Errorf("undeterminable Source type from Field, %s\n", l.SourceTag)
		}
	}
	return gauge, nil
}

func (g *Gauge) setValue(v interface{}) error {
	switch d := v.(type) {
	case int:
		g.Value = float64(int(d))
	case int32:
		g.Value = float64(int32(d))
	case int64:
		g.Value = float64(int64(d))
	case float32:
		g.Value = float64(d)
	case float64:
		g.Value = float64(d)
	default:
		return fmt.Errorf("undeterminable type %+v", d)
	}
	return nil
}

func (l *Librato) Close() error {
	return nil
}

func init() {
	outputs.Add("librato", func() outputs.Output {
		return NewLibrato(librato_api)
	})
}