// RegisterDockerEventListener registers function as event listener with docker.
// laziness defines how many seconds to wait, after an event is received, until a refresh is triggered
func RegisterDockerEventListener(client *docker.Client, function func(), wg *sync.WaitGroup, laziness int) {
wg.Add(1)
defer wg.Done()
events := make(chan *docker.APIEvents)
defer close(events)
err := client.AddEventListener((chan<- *docker.APIEvents)(events))
if err != nil {
log.Fatalf("Unable to add docker event listener: %s", err)
}
defer client.RemoveEventListener(events)
log.Info("Listening to docker events...")
for {
event := <-events
if event == nil {
continue
}
if event.Status == "start" || event.Status == "stop" || event.Status == "die" {
log.Debug("Received event %s for container %s", event.Status, event.ID[:12])
Refresh.Mu.Lock()
if !Refresh.IsTriggered {
log.Info("Triggering refresh in %d seconds", laziness)
Refresh.timer = time.AfterFunc(time.Duration(laziness)*time.Second, function)
Refresh.IsTriggered = true
}
Refresh.Mu.Unlock()
}
}
}
func generateFromEvents(client *docker.Client, configs ConfigFile) {
configs = configs.filterWatches()
if len(configs.Config) == 0 {
return
}
wg.Add(1)
defer wg.Done()
for {
if client == nil {
var err error
endpoint, err := getEndpoint()
if err != nil {
log.Printf("Bad endpoint: %s", err)
time.Sleep(10 * time.Second)
continue
}
client, err = NewDockerClient(endpoint)
if err != nil {
log.Printf("Unable to connect to docker daemon: %s", err)
time.Sleep(10 * time.Second)
continue
}
generateFromContainers(client)
}
eventChan := make(chan *docker.APIEvents, 100)
defer close(eventChan)
watching := false
for {
if client == nil {
break
}
err := client.Ping()
if err != nil {
log.Printf("Unable to ping docker daemon: %s", err)
if watching {
client.RemoveEventListener(eventChan)
watching = false
client = nil
}
time.Sleep(10 * time.Second)
break
}
if !watching {
err = client.AddEventListener(eventChan)
if err != nil && err != docker.ErrListenerAlreadyExists {
log.Printf("Error registering docker event listener: %s", err)
time.Sleep(10 * time.Second)
continue
}
watching = true
log.Println("Watching docker events")
}
select {
case event := <-eventChan:
if event == nil {
if watching {
client.RemoveEventListener(eventChan)
watching = false
client = nil
}
break
}
if event.Status == "start" || event.Status == "stop" || event.Status == "die" {
log.Printf("Received event %s for container %s", event.Status, event.ID[:12])
generateFromContainers(client)
}
case <-time.After(10 * time.Second):
// check for docker liveness
}
}
}
}