A simple HTTP to MQTT bridge

The idea of creating a simple HTTP to MQTT bridge stroke me when I was trying to integrate IFTTT with my smart-home infrastructure. Right now there is no MQTT service available in IFTTT and I still have to use Maker Webhooks to fire HTTP-request against some APIs.

My project is based on a fork of petkov's HTTP to MQTT bridge with a richer set of configuration strategies and error handling.

Usage

You can run the app on any Node JS capable server or hosting provider.

Just clone the repository and install the dependencies

$ git clone https://github.com/MiGoller/http_to_mqtt.git
$ cd http_to_mqtt
$ npm install

Now run the app ...

$ node ./index.js [<args>]

... and the app will confirm it's started.

http_to_mqtt is running on port 5000

By default the http_to_mqtt will listen on port 5000 and will try to connect to a MQTT broker on localhost listening on port 1883.

How to publish to a topic

If you want to publish a message to a topic you'll just have to post a request with a JSON-body to your instance.

$ curl -H "Content-Type: application/json" "http://localhost:5000/post"  -d '{"topic" : "MyTopic", "message" : "Hello World" }'

http_to_mqtt will respond with ok, if the bridge was able to publish the message.

OK

Hot to subscribe to a topic

Lets say you want to subscribe to a topic MySubscriptionTopic.

$ curl -ivs --raw http://localhost:5000/subscribe?topic=MySubscriptionTopic

curl with options -ivs and --raw will show incoming messages as they are received.

Look for further details on https://github.com/petkov/http_to_mqtt#subscribe-to-a-topic .

Configuration settings

http_to_mqtt let you define options for running the bridge and your MQTT broker.

MQTT settings

Setting	Description	Default	Example
URL	The URL of your MQTT broker.	`mqtt://localhost`	`mqtt://broker.hivemq.com:1883`
Username	Your MQTT username	not set / empty	`MySpecialUsername`
Password	Your MQTT password	not set / empty	`MyPassword123`
Client-ID	Your MQTT client's ID	not set / empty	`openHab`

Bridge settings

Setting	Description	Default	Example
Port	Local TCP listening port.	`5000`	`8082`
Secret	The secret key (auth key).	not set / empty	`s-bEwbqE8*_j3@9fvfGi`
Keep-alive topic	MQTT keep-alive topic	`keep_alive`
Keep-alive message	MQTT keep-alive message	`keep_alive`
Debug-mode	Enable / disable debugging	`false`	`true` or `false`

Configuration strategies

You have the choice on how to apply settings to your http_to_mqtt instance. http_to_mqtt will check for each configuration setting in the following order.

JSON file
Command line arguments
Environment variables

JSON settings-file

http_to_mqtt supports configuration by a settings-file. Just pass a JSON settings-file to the command line.

node ./index.js --settings <PathToJsonFile>

You can set any option by the command line argument's names.

Command line arguments

http_to_mqtt will pay attention on the following command line arguments passed to index.js.

Argument	Description	Default	Example
`mqtt_url`	The URL of your MQTT broker.	`mqtt://localhost`	`--mqtt_url mqtt://broker.hivemq.com:1883`
`mqtt_user`	Your MQTT username	not set / empty	`--mqtt_user MySpecialUsername`
`mqtt_pass`	Your MQTT password	not set / empty	`--mqtt_pass MyPassword123`
`mqtt_clientid`	Your MQTT client's ID	not set / empty	`--mqtt_clientid openHab`
`port`	Local TCP listening port.	`5000`	`--port 8082`
`secret`	The secret key (auth key).	not set / empty	`--secret 's-bEwbqE8*_j3@9fvfGi'`
`keep_alive_topic`	MQTT keep-alive topic	`keep_alive`	`--keep_alive_topic MyTopic`
`keep_alive_message`	MQTT keep-alive message	`keep_alive`	`--keep_alive_message MyTopic`
`debug`	Enable / disable debugging	`false`	`--debug true` or `--debug false`

Environment variables

http_to_mqtt supports environment variables for setting up the bridge. Just set the the following environment variables accordingly. This is a common method for instances running on container platforms like Docker.

Variable	Description	Default	Example
`MQTT_URL`, `MQTT_HOST`	The URL of your MQTT broker.	`mqtt://localhost`	`mqtt://broker.hivemq.com:1883`
`MQTT_USER`	Your MQTT username	not set / empty	`MySpecialUsername`
`MQTT_PASS`	Your MQTT password	not set / empty	`MyPassword123`
`MQTT_CLIENT_ID`	Your MQTT client's ID	not set / empty	`openHab`
`PORT`	Local TCP listening port.	`5000`	`8082`
`SECRET`, `AUTH_KEY`	The secret key (auth key).	not set / empty	`s-bEwbqE8*_j3@9fvfGi`
`KEEP_ALIVE_TOPIC`	MQTT keep-alive topic	`keep_alive`
`KEEP_ALIVE_MESSAGE`	MQTT keep-alive message	`keep_alive`
`DEBUG_MODE`	Enable / disable debugging	`false`	`true` or `false`

Thanks

Special thanks to petkov's HTTP to MQTT bridge.