Export

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, messages from local bus are stored into Redis stream. Upon connection reestablishment Export service consumes messages from Redis stream and sends it to the Mainflux cloud.

Install

Get the code:

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

Make:

make

Usage

cd build
./mainflux-export

Configuration

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

[exp]
  cache_pass = ""
  cache_url = "localhost:6379"
  cache_db = "0"
  log_level = "debug"
  nats = "localhost:4222"
  port = "8170"

[mqtt]
  username = "<thing_id>"
  password = "<thing_password>"
  ca = "ca.crt"
  cert = "thing.crt"
  mtls = "false"
  priv_key = "thing.key"
  retain = "false"
  skip_tls_ver = "false"
  url = "tcp://mainflux.com:1883"

[[routes]]
  mqtt_topic = "channel/<channel_id>/messages"
  subtopic = "subtopic"
  nats_topic = "export"
  type = "plain"
  workers = 10

Http port

• port - HTTP port where status of Export service can be fetched.

curl -X GET http://localhost:8170/version
{"service":"export","version":"0.0.1"}%

Redis connection

To configure Redis connection settings cache_url, cache_pass, cache_db in config.toml are used.

MQTT connection

To establish connection to MQTT broker following settings are needed:

• username - Mainflux <thing_id>
• password - Mainflux <thing_key>
• 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.

Routes

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 control number of workers that will be used for message forwarding.
• type - specifies message transformation, currently only plain is supported, meaning no transformation.

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.

In order for Export service to listen on Mainflux NATS deployed on the same machine NATS port must be exposed. Run mainflux using make run.

Environment variables

Service will look for config.toml first and if not found it will be configured with env variables and new config file specified with MF_EXPORT_CONFIG_FILE will be saved with values populated from env vars.
The service is configured using the environment variables presented in the following table. Note that any unset variables will be replaced with their default values.

Variable	Description	Default
MF_NATS_URL	Nats url	localhost:4222
MF_EXPORT_MQTT_HOST	Mqtt url where to export	tcp://localhost:1883
MF_EXPORT_MQTT_USERNAME	MQTT username, thing id in case of mainflux
MF_EXPORT_MQTT_PASSWORD	MQTT password, thing key in case of mainflux
MF_EXPORT_MQTT_CHANNEL	MQTT channel where to publish
MF_EXPORT_MQTT_SKIP_TLS	Skip tls verification	true
MF_EXPORT_MQTT_MTLS	Use MTLS for authentication	false
MF_EXPORT_MQTT_CA	CA for tls	ca.crt
MF_EXPORT_MQTT_CLIENT_CERT	Client cert for authentication in case when MTLS = true	thing.crt
MF_EXPORT_MQTT_CLIENT_PK	Client key for authentication in case when MTLS = true	thing.key
MF_EXPORT_MQTT_QOS	MQTT QOS	0
MF_EXPORT_MQTT_RETAIN	MQTT retain	false
MF_EXPORT_CONFIG_FILE	Configuration file	config.toml

for values in environment variables to take effect make sure that there is no MF_EXPORT_CONF file.

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

MF_EXPORT_PORT=8178 \
MF_EXPORT_LOG_LEVEL=debug \
MF_EXPORT_MQTT_HOST=tcp://localhost:1883 \
MF_EXPORT_MQTT_USERNAME=<thing_id> \
MF_EXPORT_MQTT_PASSWORD=<thing_key> \
MF_EXPORT_MQTT_CHANNEL=<channel_id> \
MF_EXPORT_MQTT_SKIP_TLS=true \
MF_EXPORT_MQTT_MTLS=false \
MF_EXPORT_MQTT_CA=ca.crt \
MF_EXPORT_MQTT_CLIENT_CERT=thing.crt \
MF_EXPORT_MQTT_CLIENT_PK=thing.key \
MF_EXPORT_CONFIG_FILE=export.toml \
../build/mainflux-export&

Service will be subscribed to NATS <nats_topic>.> subject and send messages to channels/<MF_EXPORT_MQTT_CHANNEL>/messages + / + <NatsSubject>. For example if you are running Mainflux on a gateway if you set nats_topic="channel" you can make export service forward messages to other Mainflux instances i.e. into to the Mainflux cloud. When message gets published to local Mainflux instance it will end on NATS as channels.<local_channel_id>.messages.subtopic, Export service will pick it up and forward it to <mqtt_topic> ending on <mqtt_topic>/channels/<local_channel_id>/messages/subtopic. Created export.toml you can edit to add different routes and use in next run.

How to save config via agent

Configuration file for Export service can be send over MQTT using Agent service. save, export,

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="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)