Mainflux Export service can send message from one Mainflux cloud to another via MQTT, or it can send messages from edge gateway to Mainflux Cloud. Export service is subscribed to local message bus and connected to MQTT broker in the cloud.
Messages collected on local message bus are redirected to the cloud. When connection is lost, if QoS2 is used, messages from the local bus are stored into file or in memory to be resent upon reconnection. Additonaly Export service publishes liveliness status to Agent via NATS subject heartbeat.export.service


Get the code:

go get github.com/mainflux/export
cd $GOPATH/github.com/mainflux/export




cd build


By default Export service looks for config file at ../configs/config.toml if no env vars are specified.

  log_level = "debug"
  nats = "localhost:4222"
  port = "8170"

  username = "<thing_id>"
  password = "<thing_password>"
  ca_path = "ca.crt"
  client_cert = ""
  client_cert_key = ""
  client_cert_path = "thing.crt"
  client_priv_key_path = "thing.key"
  mtls = "false"
  priv_key = "thing.key"
  retain = "false"
  skip_tls_ver = "false"
  url = "tcp://mainflux.com:1883"

  mqtt_topic = "channel/<channel_id>/messages"
  subtopic = "subtopic"
  nats_topic = "export"
  type = "default"
  workers = 10

  mqtt_topic = "channel/<channel_id>/messages"
  subtopic = "subtopic"
  nats_topic = "channels"
  type = "mfx"
  workers = 10

Environment variables#

Service will first look for MF_EXPORT_CONFIG_FILE for configuration and if not found it will be configured with env variables and new config file specified with MF_EXPORT_CONFIG_FILE (default value will be used if none specified) will be saved with values populated from env vars.
The service is configured using the environment variables as presented in the table. Note that any unset variables will be replaced with their default values.

For values in environment variables to take effect make sure that there is no MF_EXPORT_CONFIG_FILE file.

If you run with environment variables you can create config file:

MF_EXPORT_MQTT_HOST=tcp://localhost:1883 \

Values from environment variables will be used to populate export.toml

Http port#

  • port - HTTP port where status of Export service can be fetched.
curl -X GET http://localhost:8170/version

MQTT connection#

To establish connection to MQTT broker following settings are needed: - username - Mainflux - password - Mainflux - url - url of MQTT broker

Additionally, you will need MQTT client certificates if you enable mTLS. To obtain certificates ca.crt, thing.crt and key thing.key follow instructions here or here.


To setup MTLS connection Export service requires client certificate and mtls in config or MF_EXPORT_MQTT_MTLS must be set to true. Client certificate can be provided in a file, client_cert_path and client_cert_key_path are used for specifying path to certificate files. If MTLS is used and no certificate file paths are specified then Export will look in client_cert and client_cert_key of config file expecting certificate content stored as string.


Routes are being used for specifying which subscriber's topic(subject) goes to which publishing topic. Currently only MQTT is supported for publishing. To match Mainflux requirements mqtt_topic must contain channel/<channel_id>/messages, additional subtopics can be appended.

  • mqtt_topic - channel/<channel_id>/messages/<custom_subtopic>
  • nats_topic - Export service will be subscribed to NATS subject <nats_topic>.>
  • subtopic - messages will be published to MQTT topic <mqtt_topic>/<subtopic>/<nats_subject>, where dots in nats_subject are replaced with '/'
  • workers - specifies number of workers that will be used for message forwarding.
  • type - specifies message transformation:
  • default is for sending messages as they are received on NATS with no transformation (so they should be in SenML format for successful exporting to Mainflux cloud)
  • mfx is for messages that are being picked up on internal Mainflux NATS bus, messages that are published to local running Mainflux via MQTT will end on NATS, before sending, SenML must be extracted from Mainflux Message and then sent via MQTT to cloud. nats_topic in this case must be channels , or if you want a specific channel on local instance of Mainflux to export to cloud you can put channels.<local_mainflux_channel_id>

Before running Export service edit configs/config.toml and provide username, password and url * username - matches thing_id in Mainflux cloud instance * password - matches thing_key * channel - MQTT part of the topic where to publish MQTT data (channel/<channel_id>/messages is format of mainflux MQTT topic) and plays a part in authorization.

If Mainflux and Export service are deployed on same gateway Export can be configured to send messages from Mainflux internal NATS bus to Mainflux in a cloud. In order for Export service to listen on Mainflux NATS deployed on the same machine NATS port must be exposed. Edit Mainflux docker-compose.yml. NATS section must look like below:

    image: nats:1.3.0
    container_name: mainflux-nats
    restart: on-failure
      - mainflux-base-net
      - 4222:4222

How to save config via agent#

Configuration file for Export service can be sent over MQTT using Agent service.

mosquitto_pub -u <thing_id> -P <thing_key> -t channels/<control_ch_id>/messages/req -h localhost -p 18831  -m  "[{\"bn\":\"1:\", \"n\":\"config\", \"vs\":\"save, export, <config_file_path>, <file_content_base64>\"}]"

vs="save, export, config_file_path, file_content_base64" - vs determines where to save file and contains file content in base64 encoding payload:

b,_ := toml.Marshal(export.Config)
payload := base64.StdEncoding.EncodeToString(b)

Using configure script#

There is a configuration.sh script in a scripts directory that can be used for automatic configuration and start up of remotely deployed export. For this to work it is presumed that mainflux-export and scripts/export_start are placed in executable path on remote device. Additionally this script requires that remote device is provisioned following the steps described for provision service.

To run it first edit script to set parameters


EXTERNAL_KEY and EXTERNAL_ID are parameters posted to /mapping endpoint of provision service, MAINFLUX_HOST is location of cloud instance of Mainflux that export should connect to and MAINFLUX_USER_EMAIL and MAINFLUX_USER_PASSWORD are users credentials in the cloud.