// NewDefaultSubscriber yields a DefaultSubscriber that automatically connects to
// the configured (via config service) nsqlookupds to find nodes hosting the
// messages for the given topic
func NewDefaultSubscriber(topic string, channel string) (Subscriber, error) {
return &DefaultSubscriber{
cfg: nsqlib.NewConfig(),
topic: topic,
channel: channel,
stop: make(chan struct{}),
}, nil
}
// loadFromConfig grabs latest config, then diffs against currently loaded
func (p *HostpoolPublisher) loadFromConfig() error {
cl := config.AtPath("hailo", "service", "nsq", "writeCl").AsString("ONE")
pubHosts := getHosts(4150, "hailo", "service", "nsq", "pubHosts")
hbInterval := config.AtPath("hailo", "service", "nsq", "pubHeartbeatInterval").AsDuration("30s")
// hash and test
hash, _ := config.LastLoaded()
if p.configHash == hash {
return nil
}
p.configHash = hash
// lock now and then update everything
p.Lock()
defer p.Unlock()
canonicalHosts := make(map[string]bool)
for _, host := range pubHosts {
canonicalHosts[host] = true
// do we have a producer for this host?
if _, ok := p.producers[host]; !ok {
cfg := nsqlib.NewConfig()
cfg.HeartbeatInterval = hbInterval
prod, err := nsqlib.NewProducer(host, cfg)
if err != nil {
return err
}
prod.SetLogger(&logBridge{}, nsqlib.LogLevelDebug)
p.producers[host] = prod
}
}
// now remove any removed ones
for host, prod := range p.producers {
if !canonicalHosts[host] {
delete(p.producers, host)
prod.Stop()
}
}
// add hosts to hostpool
p.hostpool.SetHosts(pubHosts)
log.Infof("Initialized NSQ publisher with hosts %v", strings.Join(pubHosts, ", "))
// setup the other meta data
p.count = len(p.producers)
switch cl {
case "TWO":
p.cl = cl_TWO
p.n = 2
case "QUORUM":
p.cl = cl_QUORUM
p.n = p.count/2 + 1
default:
p.cl = cl_ONE // our default
p.n = 1
}
p.configHash = hash
return nil
}
// 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
}
