one_exporter.go

// Prometheus exporter for OpenNebula.
package main

import (
	"net/http"
	"os"
	"path"
	"strconv"
	"strings"

	"github.com/go-kit/kit/log"
	"github.com/go-kit/kit/log/level"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/spf13/viper"
	"gopkg.in/alecthomas/kingpin.v2"
)

type config struct {
	user     string
	password string
	endpoint string
	interval int
	host     string
	port     int
	path     string
}

func newConfig(fileName string, logger log.Logger) (config, error) {

	viper.SetDefault("endpoint", "") // "" will be set to "http://localhost:2633/RPC2" by goca
	viper.SetDefault("interval", 60)
	viper.SetDefault("path", "/metrics")
	viper.SetDefault("port", 9621)


	viper.SetConfigType("yaml")
	viper.AddConfigPath(".")

	if fileName != "" {
		level.Info(logger).Log("msg", "using provided configuration file", "file", fileName)

		dir, file := path.Split(fileName)
		viper.SetConfigName(file)
		viper.AddConfigPath(dir)
	}

	err := viper.ReadInConfig()
	if err != nil {
		return config{}, err
	}

	return config{
		user:     viper.Get("user").(string),
		password: viper.Get("password").(string),
		endpoint: viper.Get("endpoint").(string),
		interval: viper.Get("interval").(int),
		host:     viper.Get("host").(string),
		port:     viper.Get("port").(int),
		path:     viper.Get("path").(string),
	}, nil
}

func allowedLevel(logLevel string) level.Option {

	switch strings.ToLower(logLevel) {
	case "error":
		return level.AllowError()
	case "debug":
		return level.AllowDebug()
	default:
		return level.AllowInfo()
	}
}

func main() {

	logger := log.NewLogfmtLogger(log.NewSyncWriter(os.Stderr))
	logger = log.With(logger, "ts", log.DefaultTimestampUTC, "caller", log.DefaultCaller)

	cfgFile  := kingpin.Flag("config", "config file for one_exporter").Short('c').String()
	logLevel := kingpin.Flag("loglevel", "the log level to output. options are error, info or debug. defaults to info").Short('l').Default("info").String()

	kingpin.Version(Version)
	kingpin.Parse()

	logger = level.NewFilter(logger, allowedLevel(*logLevel))
	level.Info(logger).Log("msg", "starting exporter for OpenNebula")

	config, err := newConfig(*cfgFile, logger)
	if err != nil {
		level.Error(logger).Log("error", err)
		return
	}

	level.Debug(logger).Log("msg", "loaded config", "user", config.user, "endpoint", config.endpoint)

	initMetrics()
	go recordMetrics(config, logger)

	level.Info(logger).Log("msg", "starting exporter", "host", config.host, "port", config.port, "path", config.path)
	http.Handle(config.path, promhttp.Handler())

	err = http.ListenAndServe(config.host+":"+strconv.Itoa(config.port), nil)
	if err != nil {
		level.Error(logger).Log("error", err)
	}
}