forked from gliderlabs/registrator
/
registrator.go
126 lines (107 loc) · 2.92 KB
/
registrator.go
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package main
import (
"errors"
"flag"
"log"
"net/url"
"os"
"time"
"github.com/cenkalti/backoff"
dockerapi "github.com/fsouza/go-dockerclient"
)
var hostIp = flag.String("ip", "", "IP for ports mapped to the host")
var internal = flag.Bool("internal", false, "Use internal ports instead of published ones")
var refreshInterval = flag.Int("ttl-refresh", 0, "Frequency with which service TTLs are refreshed")
var refreshTtl = flag.Int("ttl", 0, "TTL for services (default is no expiry)")
func getopt(name, def string) string {
if env := os.Getenv(name); env != "" {
return env
}
return def
}
func assert(err error) {
if err != nil {
log.Fatal("registrator: ", err)
}
}
func retry(fn func() error) error {
return backoff.Retry(fn, backoff.NewExponentialBackOff())
}
func mapdefault(m map[string]string, key, default_ string) string {
v, ok := m[key]
if !ok {
return default_
}
return v
}
type ServiceRegistry interface {
Register(service *Service) error
Deregister(service *Service) error
Refresh(service *Service) error
}
func NewServiceRegistry(uri *url.URL) ServiceRegistry {
factory := map[string]func(*url.URL) ServiceRegistry{
"consul": NewConsulRegistry,
"etcd": NewEtcdRegistry,
"skydns2": NewSkydns2Registry,
}[uri.Scheme]
if factory == nil {
log.Fatal("unrecognized registry backend: ", uri.Scheme)
}
log.Println("registrator: Using", uri.Scheme, "registry backend at", uri)
return factory(uri)
}
func main() {
flag.Parse()
if *hostIp != "" {
log.Println("registrator: Forcing host IP to", *hostIp)
}
if (*refreshTtl == 0 && *refreshInterval > 0) || (*refreshTtl > 0 && *refreshInterval == 0) {
assert(errors.New("-ttl and -ttl-refresh must be specified together or not at all"))
} else if *refreshTtl > 0 && *refreshTtl <= *refreshInterval {
assert(errors.New("-ttl must be greater than -ttl-refresh"))
}
docker, err := dockerapi.NewClient(getopt("DOCKER_HOST", "unix:///var/run/docker.sock"))
assert(err)
uri, err := url.Parse(flag.Arg(0))
assert(err)
registry := NewServiceRegistry(uri)
bridge := &RegistryBridge{
docker: docker,
registry: registry,
services: make(map[string][]*Service),
}
containers, err := docker.ListContainers(dockerapi.ListContainersOptions{})
assert(err)
for _, listing := range containers {
bridge.Add(listing.ID)
}
quit := make(chan struct{})
if *refreshInterval > 0 {
ticker := time.NewTicker(time.Duration(*refreshInterval) * time.Second)
go func() {
for {
select {
case <-ticker.C:
bridge.Refresh()
case <-quit:
ticker.Stop()
return
}
}
}()
}
events := make(chan *dockerapi.APIEvents)
assert(docker.AddEventListener(events))
log.Println("registrator: Listening for Docker events...")
for msg := range events {
switch msg.Status {
case "start":
go bridge.Add(msg.ID)
case "die":
go bridge.Remove(msg.ID)
}
}
close(quit)
log.Fatal("registrator: docker event loop closed") // todo: reconnect?
}