main.go

package main

import (
	"os"
	"os/signal"
	"strings"
	"syscall"

	"github.com/miekg/dns"
	log "github.com/sirupsen/logrus"
	"github.com/urfave/cli"
)

const version = "0.4.4"

var (
	compress         bool
	dom              string
	regContainerName bool
	regHostName      bool
	ttl              uint32
)

func main() {
	app := cli.NewApp()
	app.Name = "dkdns"
	app.Usage = "Docker Dynamic DNS"
	app.Version = version
	app.Flags = []cli.Flag{
		&cli.BoolFlag{
			Name:  "debug, d",
			Usage: "Enable debugging.",
		},
		&cli.IntFlag{
			Name:  "resync, r",
			Value: 0,
			Usage: "Periodically resync all containers from docker hosts.",
		},
		&cli.StringFlag{
			Name:  "domain, dom",
			Value: "dkdns.",
			Usage: "Top level domain to serve.",
		},
		&cli.BoolFlag{
			Name:  "no-hostname",
			Usage: "Don't register container hostnames.",
		},
		&cli.BoolFlag{
			Name:  "no-containername",
			Usage: "Don't register container names.",
		},
		&cli.StringFlag{
			Name:  "listen",
			Usage: "Address and port to listen on",
			Value: ":53",
		},
		&cli.BoolFlag{
			Name:  "compress",
			Usage: "Compress dns replies.",
		},
		&cli.UintFlag{
			Name:  "ttl",
			Usage: "TTL for dns replies.",
			Value: 5,
		},
		&cli.StringSliceFlag{
			Name:  "docker-endpoint",
			Usage: "URL to docker endpoint(s)",
		},
		&cli.StringFlag{
			Name:  "ca",
			Usage: "Path to docker CA if using TLS",
		},
		&cli.StringFlag{
			Name:  "cert",
			Usage: "Path to docker cert if using TLS",
		},
		&cli.StringFlag{
			Name:  "key",
			Usage: "Path to docker key if using TLS",
		},
		&cli.BoolFlag{
			Name:  "no-validate",
			Usage: "Don't validate ssl connections.",
		},
	}
	app.Action = Run
	err := app.Run(os.Args)
	if err != nil {
		panic(err)
	}
}

func Run(ctx *cli.Context) error {
	log.SetFormatter(&log.TextFormatter{
		//ForceColors: false,
		//DisableColors: true,
		DisableTimestamp: false,
		FullTimestamp:    true,
	})

	if ctx.Bool("debug") {
		log.SetLevel(log.DebugLevel)
		log.Info("Debug logging enabled")
	}
	log.WithField("Level", log.GetLevel()).Info("Log level set")

	compress = ctx.Bool("compress")
	dom = strings.TrimSuffix(normalizeName(ctx.String("domain")), ".") + "."
	regContainerName = !ctx.Bool("no-containername")
	regHostName = !ctx.Bool("no-hostname")
	ttl = uint32(ctx.Uint("ttl"))

	log.WithField("Domain", dom).Debug("Domain set")
	log.WithField("Compress", compress).Debug("Compression set")

	dns.HandleFunc(".", handle)
	go serve("tcp", ctx.String("listen"))
	go serve("udp", ctx.String("listen"))

	endpoints := ctx.StringSlice("docker-endpoint")
	if len(endpoints) == 0 {
		endpoints = []string{"unix:///var/run/docker.sock"}
	}

	go monDocker(endpoints, ctx.String("ca"), ctx.String("cert"), ctx.String("key"), !ctx.Bool("no-validate"), ctx.Int("resync"))

	sig := make(chan os.Signal, 1)
	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
	s := <-sig
	log.Infof("Signal (%s) received, stopping\n", s)
	return nil
}