Having set up some MQTT sensors and controllable lights the next step was to start tying things together with a nicer interface than mosquitto_pub and mosquitto_sub. I don’t yet have enough devices setup to be able to do some useful scripting (turning on the snug light when the study is cold is not helpful), but a web control interface makes things easier to work with as well as providing a suitable platform for expansion as I add devices.

There are various home automation projects out there to help with this. I’d previously poked openHAB and found it quite complex, and I saw reference to Domoticz which looked viable, but in the end I settled on Home Assistant, which is written in Python and has a good range of integrations available out of the box.

I shoved the install into a systemd-nspawn container (I have an Ansible setup which makes spinning one of these up with a basic Debian install simple, and it makes it easy to cleanly tear things down as well). One downside of Home Assistant is that it decides it’s going to install various Python modules once you actually configure up some of its integrations. This makes me a little uncomfortable, but I set it up with its own virtualenv to make it easy to see what had been pulled in. Additionally I separated out the logs, config and state database, all of which normally go in ~/.homeassistant/. My systemd service file went in /etc/systemd/system/home-assistant.service and looks like:

Description=Home Assistant

ExecStart=/srv/hass/bin/hass -c /etc/homeassistant --log-file /var/log/homeassistant/homeassistant.log



Moving the state database needs an edit to /etc/homeassistant/configuration.yaml (a default will be created on first startup, I’ll only mention the changes I made here):

  db_url: sqlite:///var/lib/homeassistant/home-assistant_v2.db

I disabled the Home Assistant cloud piece, as I’m not planning on using it:

# cloud:

And the introduction card:

# introduction:

The existing MQTT broker was easily plumbed in:

  broker: mqtt-host
  username: hass
  password: !secret mqtt_password
  port: 8883
  certificate: /etc/ssl/certs/ca-certificates.crt

Then the study temperature sensor (part of the existing sensor block that had weather prediction):

  - platform: mqtt
    name: "Study Temperature"
    state_topic: "collectd/mqtt.o362.us/mqtt/temperature-study"
    value_template: "{{ value.split(':')[1] }}"
    device_class: "temperature"
    unit_of_measurement: "°C"

The templating ability let me continue to log into MQTT in a format collectd could parse, while also being able to pull the information into Home Assistant.

Finally the Sonoff controlled light:

  - platform: mqtt
    name: snug
    command_topic: 'cmnd/sonoff-snug/power'

I set http_password (to prevent unauthenticated access) and mqtt_password in /etc/homeassistant/secrets.yaml. Then systemctl start home-assistant brought the system up on http://hass-host:8123/, and the default interface presented the study temperature and a control for the snug light, as well as the default indicators of whether the sun is up or not and the local weather status.

I do have a few niggles with Home Assistant:

  • Single password for access: There’s one password for accessing the API endpoint, so no ability to give different users different access or limit what an external integration can do.
  • Wants an entire subdomain: This is a common issue with webapps; they don’t want to live in a subdirectory under a main site (I also have this issue with my UniFi controller and Keybase, who don’t want to believe my main website is old skool with /~noodles/). There’s an open configurable webroot feature request, but no sign of it getting resolved. Sadly it involves work to both the backend and the frontend - I think a modicum of hacking could fix up the backend bits, but have no idea where to start with a Polymer frontend.
  • Installs its own software: I don’t like the fact the installation of Python modules isn’t an up front thing. I’d rather be able to pull a dependency file easily into Ansible and lock down the installation of new things. I can probably get around this by enabling plugins, allowing the modules to be installed and then locking down permissions but it’s kludgy and feels fragile.
  • Textual configuration: I’m not really sure I have a good solution to this, but it’s clunky to have to do all the configuration via a text file (and I love scriptable configuration). This isn’t something that’s going to work out of the box for non-technical users, and even for those of us happy hand editing YAML there’s a lot of functionality that’s hard to discover without some digging. One of my original hopes with Home Automation was to get a better central heating control and if it’s not usable by any household member it isn’t going to count as better.

Some of these are works in progress, some are down to my personal preferences. There’s active development, which is great to see, and plenty of documentation - both offical on the project website, and in the community forums. And one of the nice things about tying everything together with MQTT is that if I do decide Home Assistant isn’t the right thing down the line, I should be able to drop in anything else that can deal with an MQTT broker.