HTTP to MQTT bridge

The idea of creating HTTP to MQTT bridge appeared when I was trying to integrate Google Assistant with my Home Assistant after watching BRUH Automation video. Right now there is no MQTT service available in IFTTT. Existing integration solution uses Maker Webhooks which requires that your HA is publically accessible, which I think brings some security concerns or simply not always possible to set up.

The HTTP to MQTT bridge should feel that gap. The idea is to receive signals using HTTP requests and transfer them to your MQTT broker, which is connected to HA. The HTTP to MQTT bridge is written using Node JS with Express for HTTP server and MQTT.js client.

Usage

The app could be hosted on any Node JS hosting.

Heroku

I prefer Heroku: Cloud Application Platform for its simplicity.

1. Configure Home Assistant MQTT trigger.
2. Configure CloudMQTT. Here is a great video tutorial on how to do that: https://www.youtube.com/watch?v=VaWdvVVYU3A
3. HTTP to MQTT bridge app.
4. Add below (Config Variables)(https://devcenter.heroku.com/articles/config-vars#setting-up-config-vars-for-a-deployed-application) to your Heroku app.
   • AUTH_KEY - can be any string eg.: 912ec803b2ce49e4a541068d495ab570.
   • MQTT_HOST - the host of your MQTT broker (eg.: mqtts://k99.cloudmqtt.com:21234).
   • MQTT_USER
   • MQTT_PASS
5. Create IFTTT applet the same way as described in BRUH Automation video.
6. Configure Maker Webhooks service with below parameters.
   • URL: https://<app_name>.herokuapp.com/post/
   • Method: POST
   • Content Type: application/json
   • Body: {"topic":"<mqtt_topic>","message":"<mqtt_message>","key":"<AUTH_KEY>"}

Subscribe to latest version

Additionally you can make Heroku to update HTTP to MQTT bridge app to the latest available version from GitHub repository automatically. To do this follow the instruction on Heroku help page.

Improve response time

After 30 minutes of inactivity Heroku will put your app into sleep mode. This will result in ~10 seconds response time. To prevent Heroku from putting your app into sleep mode ping it every 10 minutes or so. You can do that by sending regular HTTP GET request to http://your_app/keep_alive/. But be carefull. Heroku free quota is 550 hours per month. Without sleeping your app will be allowed to run only 22 days a month. Additionally keep_alive method will send a simple MQTT message to prevent the broker from sleeping as well. The topic and message can be configured using Heroku environment variables KEEP_ALIVE_TOPIC and KEEP_ALIVE_MESSAGE and both are set to “keep_alive” by default.

Home Assistant Setup

You can even configure HA to ping HTTP to MQTT bridge every 10 minutes during daytime. Below is an example of how to do that:

rest_command:
  http_to_mqtt_keep_alive:
    url: https://<your_app_address>/keep_alive/
    method: get

automation:
  alias: HTTP to MQTT keep alive
  trigger:
    platform: time
    minutes: '/10'
    seconds: 00
  condition:
    condition: time
    after: '7:30:00'
    before: '23:59:59'
  action:
    service: rest_command.http_to_mqtt_keep_alive

Use Your Own Server

You can run this on basically anything that runs NodeJS.

1. Clone the repository
2. Run index.js

Examples

Publish to a topic

Clone the repository and run http_to_mqtt.

By default the http_to_mqtt will listen on port 5000 and connect to the localhost MQTT Broker.
The MQTT Broker (and other settings) can be specified by environment variables.

git clone https://github.com/petkov/http_to_mqtt.git
cd http_to_mqtt
node index.js

output:

Node app is running on port 5000

Publish a message to the topic 'MyTopic'

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

output:

OK

Subscribe to a topic

You can subscribe to a topic. http_to_mqtt will keep the connection open and wait for a messages from the MQTT Broker and will send them to the response each time a message is handled.

git clone https://github.com/petkov/http_to_mqtt.git
cd http_to_mqtt
node index.js

output:

Node app is running on port 5000

Publish a message to the topic 'MyTopic'. Use -ivs --raw to see messages come in as they are received.

curl -ivs --raw localhost:5000/subscribe?topic=MyTopic

output:

*   Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 5000 (#0)
> GET /subscribe?topic=MyTopic HTTP/1.1
> Host: localhost:5000
> User-Agent: curl/7.54.1
> Accept: */*
>

Whenever a message is published to the topic MyTopic curl will output the message.

Use mosquitto_pub to publish a message:

mosquitto_pub -t 'MyTopic' -m 'I sent this message using Mosquitto'

curl output:

<
23
I sent this message using Mosquitto

Specific Use Cases

Plex

Plex has the ability to specify web hooks.

We must use some query parameters to tell http_to_mqtt to handle certain things specific to our use case.

• topic=/plex/playback : Since Plex does not know which MQTT topic to post to, we must specify that via the topic query parameter. This can be anything.
• single=thumb : Plex send the user's thumbnail as the 'thumb' file. Setting the single query parameter tells http_to_mqtt to handle single file uploads.
• path=payload : The information we care about is specified by the payload property of the JSON uploaded. Tell http_to_mqtt that that is the message that should be published.

http://localhost:5000/post?topic=/plex/playback&single=thumb&path=payload

Thanks

Special thanks to Ben from BRUH Automation for awesome tutorials which inspired me to do this project.