Configuration for the MQTT stack is set through the examples/modules/cloud/overlay-mqtt.conf file and the Kconfig options defined in examples/modules/cloud/Kconfig.cloud_mqtt. The following are the main options for controlling the MQTT module:
CONFIG_APP_CLOUD_MQTTCONFIG_APP_CLOUD_MQTT_PROVISION_CREDENTIALSCONFIG_APP_CLOUD_MQTT_HOSTNAMECONFIG_APP_CLOUD_MQTT_CLIENT_IDCONFIG_APP_CLOUD_MQTT_CLIENT_ID_BUFFER_SIZECONFIG_APP_CLOUD_MQTT_TOPIC_SIZE_MAXCONFIG_APP_CLOUD_MQTT_PUB_TOPICCONFIG_APP_CLOUD_MQTT_SUB_TOPICCONFIG_APP_CLOUD_MQTT_SHELLCONFIG_APP_CLOUD_MQTT_PAYLOAD_BUFFER_MAX_SIZECONFIG_APP_CLOUD_MQTT_SHADOW_RESPONSE_BUFFER_MAX_SIZECONFIG_APP_CLOUD_MQTT_BACKOFF_INITIAL_SECONDSCONFIG_APP_CLOUD_MQTT_BACKOFF_TYPE_LINEARCONFIG_APP_CLOUD_MQTT_BACKOFF_TYPE_EXPONENTIALCONFIG_APP_CLOUD_MQTT_BACKOFF_TYPE_NONECONFIG_APP_CLOUD_MQTT_BACKOFF_LINEAR_INCREMENT_SECONDSCONFIG_APP_CLOUD_MQTT_BACKOFF_MAX_SECONDSCONFIG_APP_CLOUD_MQTT_THREAD_STACK_SIZECONFIG_APP_CLOUD_MQTT_MESSAGE_QUEUE_SIZECONFIG_APP_CLOUD_MQTT_WATCHDOG_TIMEOUT_SECONDSCONFIG_APP_CLOUD_MQTT_MSG_PROCESSING_TIMEOUT_SECONDS