func (r *Regions) listenChanges() {
for {
// look out for region changes PUBbed via NSQ -- subscribe via a random ephemeral channel
channel := fmt.Sprintf("g%v#ephemeral", rand.Uint32())
subscriber, err := nsq.NewDefaultGlobalSubscriber(topicName, channel)
if err != nil {
log.Warnf("[Ingester] Failed to attach to topic '%v' topic for ingesting events: %v", topicName, err)
time.Sleep(time.Second * 5)
continue
}
subscriber.AddHandler(nsqlib.HandlerFunc(func(m *nsqlib.Message) error {
// Notify observers
r.observersMtx.RLock()
defer r.observersMtx.RUnlock()
for _, ch := range r.observers {
// Non-blocking send
select {
case ch <- true:
default:
}
}
return nil
}))
log.Infof("[Config Load] Subscribing to region.reload")
if err := subscriber.Connect(); err != nil {
log.Warnf("[Config Load] Failed to connect to NSQ for region changes: %v", err)
time.Sleep(time.Second * 5)
continue
}
// Block until killed
r.Wait()
subscriber.Disconnect()
return
}
}
// NewServiceLoader returns a loader that reads config from config service
func NewServiceLoader(c *Config, addr, service, region, env string) (*Loader, error) {
// define our hierarchy:
// H2:BASE
// H2:BASE:<service-name>
// H2:REGION:<aws region>
// H2:REGION:<aws region>:<service-name>
// H2:ENV:<env>
// H2:ENV:<env>:<service-name>
hierarchy := []string{
"H2:BASE",
fmt.Sprintf("H2:BASE:%s", service),
fmt.Sprintf("H2:REGION:%s", region),
fmt.Sprintf("H2:REGION:%s:%s", region, service),
fmt.Sprintf("H2:ENV:%s", env),
fmt.Sprintf("H2:ENV:%s:%s", env, service),
}
// construct URL
if !strings.Contains(addr, "://") {
addr = "https://" + addr
}
addr = strings.TrimRight(addr, "/") + "/compile"
u, err := url.Parse(addr)
if err != nil {
return nil, fmt.Errorf("Failed to parse config service address: %v", err)
}
q := u.Query()
q.Set("ids", strings.Join(hierarchy, ","))
u.RawQuery = q.Encode()
configUrl := u.String()
log.Infof("[Config] Initialising service loader for service '%s' in region '%s' in '%s' environment via URL %s", service, region, env, configUrl)
rdr := func() (io.ReadCloser, error) {
rsp, err := http.Get(configUrl)
if err != nil {
log.Errorf("[Config] Failed to load config via %s: %v", configUrl, err)
return nil, fmt.Errorf("Failed to load config via %s: %v", configUrl, err)
}
defer rsp.Body.Close()
if rsp.StatusCode != 200 {
log.Errorf("[Config] Failed to load config via %s - status code %v", configUrl, rsp.StatusCode)
return nil, fmt.Errorf("Failed to load config via %s - status code %v", configUrl, rsp.StatusCode)
}
b, _ := ioutil.ReadAll(rsp.Body)
loaded := make(map[string]interface{})
err = json.Unmarshal(b, &loaded)
if err != nil {
log.Errorf("[Config] Unable to unmarshal loaded config: %v", err)
return nil, fmt.Errorf("Unable to unmarshal loaded config: %v", err)
}
b, err = json.Marshal(loaded["config"])
if err != nil {
log.Errorf("[Config] Unable to unmarshal loaded config: %v", err)
return nil, fmt.Errorf("Unable to unmarshal loaded config: %v", err)
}
rdr := ioutil.NopCloser(bytes.NewReader(b))
return rdr, nil
}
changesChan := make(chan bool)
l := NewLoader(c, changesChan, rdr)
go func() {
// wait until loaded
l.reload()
// look out for config changes PUBbed via NSQ -- subscribe via a random ephemeral channel
channel := fmt.Sprintf("g%v#ephemeral", rand.Uint32())
consumer, err := nsqlib.NewConsumer("config.reload", channel, nsqlib.NewConfig())
if err != nil {
log.Warnf("[Config] Failed to create NSQ reader to pickup config changes (fast reload disabled): ch=%v %v", channel, err)
return
}
consumer.AddHandler(nsqlib.HandlerFunc(func(m *nsqlib.Message) error {
changesChan <- true
return nil
}))
// now configure it -- NOT via lookupd! There is a bug we think!
subHosts := AtPath("hailo", "service", "nsq", "subHosts").AsHostnameArray(4150)
if len(subHosts) == 0 {
log.Warnf("[Config] No subHosts defined for config.reload topic (fast reload disabled)")
return
}
log.Infof("[Config Load] Subscribing to config.reload (for fast config reloads) via NSQ hosts: %v", subHosts)
if err := consumer.ConnectToNSQDs(subHosts); err != nil {
log.Warnf("[Config Load] Failed to connect to NSQ for config changes (fast reload disabled): %v", err)
return
}
// Wait for the Loader to be killed, and then stop the NSQ reader
l.Wait()
consumer.Stop()
}()
return l, nil
}
