I'm having an intermittent issue with go trying to connect to AWS MQTT. Sometimes it works fine, other times not so much. When I connect I get this error: Connection lost before Subscribe completed
I'm really not sure why it does this, at first everything seemed to work fine but now it throws this error more often than not. Here's the code that I'm using to connect:
type ServerConnection struct {
Cert tls.Certificate
Host string
Port int
Path string
Topic string
Qos int
Messages chan MQTT.Message
Control chan os.Signal
}
func (server *ServerConnection) Start() error {
cid := uuid.New().String()
connOpts := &MQTT.ClientOptions{
ClientID: cid,
CleanSession: true,
AutoReconnect: true,
MaxReconnectInterval: 1 * time.Second,
KeepAlive: 30000,
TLSConfig: tls.Config{Certificates: []tls.Certificate{server.Cert}},
}
connOpts.SetConnectTimeout(30 * time.Second)
connOpts.SetDefaultPublishHandler(func(client MQTT.Client, msg MQTT.Message) {
server.Messages <- msg
})
brokerURL := fmt.Sprintf("tcps://%s:%d%s", server.Host, server.Port, server.Path)
connOpts.AddBroker(brokerURL)
mqttClient := MQTT.NewClient(connOpts)
if token := mqttClient.Connect(); token.Wait() && token.Error() != nil {
return token.Error()
}
// Subscribe
go func() {
log.Printf("subscribing")
if token := mqttClient.Subscribe(server.Topic, byte(server.Qos), nil); token.Wait() && token.Error() != nil {
fmt.Println(token.Error())
os.Exit(1)
}
log.Printf("subscribed")
}()
server.ProcessMessages()
log.Println("[MQTT] Connected")
quit := make(chan struct{})
signal.Notify(server.Control, os.Interrupt)
go func() {
<-server.Control
mqttClient.Disconnect(250)
fmt.Println("[MQTT] Disconnect")
quit <- struct{}{}
}()
<-quit
return nil
}
Basically you need to put the subscribe methid call inside the onConnectHandler, this will make sure that the subscribe is being called upon successful connection (and reconnect) The handler is defined in the client options.