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apkmqttpahogomobilegomobile-android

gomobile build, the Paho mqtt client cannot connect to mqtt broker in APK

I am working on a project where I need to use gomobile tool to create an Android app. The sample code I have in Go is as below

    var broker = "127.0.0.1"
    //var broker = "broker.mqttdashboard.com"
    var port = 1883
    opts := mqtt.NewClientOptions()
    opts.AddBroker(fmt.Sprintf("tcp://%s:%d", broker, port))
    opts.SetClientID("go_mqtt_client")
    opts.SetConnectionLostHandler(connectLostHandler) // define what to do when connection is lost
    client := mqtt.NewClient(opts)
    tokenClient := client.Connect()
    if tokenClient.Wait() && tokenClient.Error() != nil {
        panic(tokenClient.Error())
    }
    ...

When I bind this code using "gomobile bind", generating the Golang plugin and calling them inside the android project there is no issue. Connections is satisfied and I can verify the local mqtt broker (mosquitto) and the mqtt client app are communicating as well.

But when I generate the APK file using "gomobile build -target=android", the connect function generates and error. To be able to test the logs i used a public broker instead of the local mqtt broker. I replaced the

var broker = "127.0.0.1"

by the HiveMQ public broker address (I have already validated the public broker functionality)

var broker = "broker.mqttdashboard.com"

It seems like there is an issue with connecting from mqtt client app to mqtt broker. Here is the exact error message I found in logs:

E/Go: panic: network Error : dial tcp: lookup broker.mqttdashboard.com: No address associated with hostname goroutine 11 [running]: E/GoLog: panic: network Error : dial tcp: lookup broker.mqttdashboard.com: No address associated with hostname E/Go: main.starting()

This is generated by "panic(tokenClient.Error())" part in my code.

Any idea why the connection is not settled using "gomobile build", while it is working when I use "gomobile bind" ?

Solution

  • Here is how I could fix the issue.

    1. I added the AndoridManifest.xml file to the same directory that the main go package is.

    2. Added the following line in between the manifest tags (<manifest> )

      <uses-permission android:name="android.permission.INTERNET">