Device options: allow to change MQTT connection keepalive value

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+## Added
+- Introduce the `KeepAlive` device option to configure the MQTT connection keepalive. Default to 30s,
+  which was the value used before.
+
 ## [0.90.2] - 2022-07-04
 ## Added
 - Introduce the `DeviceOptions` struct to expose all possible configuration options for the device.

device/device_opts.go

@@ -17,6 +17,7 @@ package device
 import (
 	"crypto/x509"
 	"errors"
+	"time"
 
 	"gorm.io/gorm"
 )
@@ -51,6 +52,12 @@ type DeviceOptions struct {
 	// MQTT client. It will use the PersistencyDir when it is activated.
 	UseMqttStore bool
 
+	// KeepAlive defines the amount of time that the MQTT client
+	// should wait before sending a PING request to the broker. This will
+	// allow the MQTT client to know that a connection has not been lost with Astarte.
+	// Defaults to 30 seconds.
+	KeepAlive time.Duration
+
 	// PersistencyDir is a known path that will be used by the SDK for MQTT
 	// persistency, for the default database if used, and for crypto storage unless
 	// CryptoDir is specified.
@@ -96,6 +103,7 @@ func NewDeviceOptions() DeviceOptions {
 		AutoReconnect:       true,
 		ConnectRetry:        true,
 		MaxRetries:          10,
+		KeepAlive:           30 * time.Second,
 	}
 }
 

device/protocol_mqtt_v1.go

@@ -44,6 +44,7 @@ func (d *Device) initializeMQTTClient() error {
 	opts.SetClientID(fmt.Sprintf("%s/%s", d.realm, d.deviceID))
 	opts.SetConnectTimeout(30 * time.Second)
 	opts.SetCleanSession(false)
+	opts.SetKeepAlive(d.opts.KeepAlive)
 
 	if d.opts.UseMqttStore {
 		s := mqtt.NewFileStore(filepath.Join(d.opts.PersistencyDir, "mqttstore"))