CODEWITHSUNDEEP
gomqtt
NeitoFR
NeitoFR

Reputation: 807

Keep a MQTT Go client running

I think it is a silly question, I need a MQTT Client to keep running after connection and subscription. I never encountered the problem because my MQTT clients are always coupled with an HTTP server, and when launching a HTTP server, the code don't stop running.

But in the present use case I only need a MQTT Client to subscribe to some topic and stay alive.

Here is what I do (the function just connect to a broker and subcribe to one topic.)

func main() {
    godotenv.Load("./.env")
    _initMqttConnection()
}

I need the client to stay connected and not stop just after the subscription is done.

How to perform that simple thing ?

Edit 1 : Complete Code 

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"strings"

	"github.com/yosssi/gmq/mqtt"
	"github.com/yosssi/gmq/mqtt/client"

	"github.com/joho/godotenv"

	"github.com/skratchdot/open-golang/open"
)

var cli *client.Client

func _initMqttConnection() {
	cli = client.New(&client.Options{
		ErrorHandler: func(err error) {
			fmt.Println(err)
		},
	})
	defer cli.Terminate()
	log.Println("Connecting to " + os.Getenv("mqtt_host"))

	err := cli.Connect(&client.ConnectOptions{
		Network:  "tcp",
		Address:  os.Getenv("mqtt_host"),
		UserName: []byte(os.Getenv("mqtt_user")),
		Password: []byte(os.Getenv("mqtt_password")),
		ClientID: []byte("mqtt_video_launcher"),
	})
	if err != nil {
		log.Println("Error 1")
		panic(err)
	}
	log.Println("Connected to MQTT")

	topic_to_sub := []byte("/" + os.Getenv("video_topic"))

	err = cli.Subscribe(&client.SubscribeOptions{
		SubReqs: []*client.SubReq{
			&client.SubReq{
				TopicFilter: topic_to_sub,
				QoS:         mqtt.QoS0,
				Handler: func(topicName, message []byte) {
					//do struff with message
          fmt.Println(string(topicName), string(message))
				},
			},
		},
	})
	if err != nil {
		panic(err)
	}
	log.Println("Subscription OK : " + string(topic_to_sub[:len(topic_to_sub)]))
}

func main() {
	godotenv.Load("./.env")
	_initMqttConnection()
}

The temporary solution I use is adding : 

http.ListenAndServe(":", nil)

at the end.

Upvotes: 0

Views: 2019

Answers (1)

Raunak Singwi
Raunak Singwi

Reputation: 21

You have to make the program run infinitely or unless you want to explicitly end it (Cntrl c). One good solution that worked for me is to wait for a channel before exiting the main function and that channel can keep listening for an interrupt.

Eg:

func main() {

    keepAlive := make(chan os.Signal)
    signal.Notify(keepAlive, os.Interrupt, syscall.SIGTERM)

    // All your code

    <-keepAlive
}

Upvotes: 2

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