Created a rough draft describing the MQTT Bridge setup

source/_posts/2016-02-09-Smarter-Smart-Things-with-MQTT-and-Home-Assistant.markdown

@@ -0,0 +1,191 @@
+---
+layout: post
+title: "Smarter Smart Things with MQTT and Home Assistant"
+description: "Jer and St. John describe how they connected SmartThings with Home Assistant."
+date: 2016-02-09 10:10 -0700
+date_formatted: "February 09, 2016"
+author: Jeremiah Wuenschel and St. John Johnson
+comments: true
+categories: User-Stories
+og_image: /images/blog/2016-02-09-Smarter-Smart-Things-with-MQTT-and-Home-Assistant.jpg
+---
+
+
+_This is a guest post by Home Assistant users [Jeremiah Wuenschel](https://github.com/jer) and [St. John Johnson](https://github.com/stjohnjohnson)._
+
+
+### Why combine SmartThings and Home Assistant?
+
+
+### Bridge Design
+**HTTP Endpoint**: There are really only 2 ways to communicate with the SmartThings hub that we could find. The easiest approach is to create a RESTful SmartApp authenticated with OAuth that provides state changes via HTTP directly. This approach is pretty straightforward to implement, but it requires communication with the SmartThings cloud service, and can't be done entirely on your LAN. We hoped to keep all communication internal, and came up with a second approach.
+
+**Custom Device Type:** SmartThings custom device types allow developers to define handlers for HTTP events received directly over the local network by the SmartThings hub. Messages received are authenticated by MAC address, and can contain arbitrary strings in their payload. Since a Device Type is only ever tied to a single device, we need to add a SmartApp to the mix in order to translate events between individual devices and our special Home Assistant Bridge device. Here is what we have so far:
+```
+Z-Wave Switch        |
+Zigbee motion sensor |<---> Bridge App <---> Bridge Device Type <---> <Local network>
+Z-Wave light bulb    |
+```
+
+On the Home Assistant side, there is a powerful platform available based on the MQTT lightweight message bus protocol. Everything from lights to switches to temperature sensors can be defined in Home Assistant as an MQTT component, so it makes for a convenient integration point. This requires an MQTT broker for handling the message bus, and one last piece to translate between the HTTP that SmartThings supports and MQTT.
+
+Here is the final sequence of events:
+
+![SmartThings Bridge Sequence]("/images/blog/2016-02-smartthings/SmartThings-HomeAssistant.png" "SmartThings Bridge Sequence")
+
+
+There are a lot of stops along the way for these events, but each piece is a simple translation layer to shuttle the events between systems.
+
+## Setting up the MQTT bridge
+
+### MQTT
+
+Assuming that you already have Home Assistant and Smart Things running, you wil first want to get an MQTT broker running. There are a handful of [MQTT][mosquitto] [brokers][emqttd] available in Open Source land. We chose [Mosca][mosca] for its simplicity.
+
+There is very little you need to do to get Mosca running. The easiest approach is to install [Docker][docker], and run a command like the following:
+
+    $ docker run \
+        -d \
+        --name="mqtt" \
+        -v /opt/mosca:/db \
+        -p 1883:1883 \
+        matteocollina/mosca
+
+
+This will start Mosca up inside of a docker container, while keeping persistent storage for Mosca in `/opt/mosca`. The default configuration is the only thing we need to get things up and running.
+
+If you don't want to mess with Docker and can get node.js installed without trouble, the [Standalone][mosca-standalone] instructions are all you need.
+
+### MQTT Bridge
+
+This is the small piece of magic that bridges the gap between MQTT and SmartThings. It is a node.js app, and like Mosca it is probably easiest to install with Docker:
+
+    $ docker run \
+        -d \
+        --name="mqtt-bridge" \
+        -v /opt/mqtt-bridge:/config \
+        -p 8080:8080 \
+        stjohnjohnson/smartthings-mqtt-bridge
+
+The code for this bridge is [on Github][mqtt-bridge] if you want to start it up independently.
+
+The MQTT Bridge only needs to know where your MQTT broker lives. If you are using these docker commands as-is, edit `/opt/mqtt-bridge/config.yml` to look like this:
+
+```yaml
+---
+mqtt:
+    host: localhost
+```
+
+Restart the bridge, and you are ready to go:
+
+    $ docker restart mqtt-bridge
+
+### SmartThing
+
+The next step is the device type. Go to the [Smart Things Device IDE][ide-dt] and `Create New Device Handler`. Choose `From Code` and paste in the [MQTT Bridge Device Code][devicetype]. Click Save.
+
+Now to install your new Device Handler. Go back to `My Devices` in the IDE, and click `New Device`. Enter a name, and pick any random set of characters for the Device Network Id (this will automatically update later). For Type, scroll to the bottom of the list and find your newly created `MQTT Bridge`. Fill in the other boxes however you like.
+
+Go back to `My Devices`, and click on your new device in the list. This will bring up a page that allows you to edit your device's Preferences. Click `edit` and fill in the 3 pieces of information it asks for.
+
+    MQTT Bridge IP Address: <IP address of the MQTT Bridge from the previous step>
+    MQTT Bridge Port: <8080 if you have changed nothing in the previous commands>
+    MQTT Bridge MAC Address: <Mac address of whatever machine is running the Bridge code>
+
+This will create the link between SmartThings and the MQTT Bridge.
+
+### SmartApp
+
+The last step is to setup the SmartApp. After this, any registered devices will start sending their events to MQTT.
+
+Go to the [Smart App IDE][ide-app]. Click `New SmartApp`, followed by `From Code`. Paste in the [MQTT Bridge SmartApp code][smartapp] and click `save`. In the SmartThings mobile app, add the new SmartApp and configure it with your devices and MQTT Bridge device. Clicking `done` will subscribe SmartThings to your MQTT broker and begin 2-way propagation of events.
+
+### Configure Home Assistant
+
+To add SmartThings devices to Home Assistant over MQTT, first enable MQTT in Home Assistant:
+
+```yaml
+mqtt:
+  broker: localhost
+```
+
+Replace `localhost` with the location of the running MQTT Broker. Devices from the MQTT Bridge are published to the path `/smartthings/<Device Name>/<Atribute>`
+
+For example, my Dimmer Z-Wave Lamp is called "Fireplace Lights" in SmartThings. The following topics are published:
+
+    # Brightness (0-99)
+    /smartthings/Fireplace Lights/level
+    # Switch State (on|off)
+    /smartthings/Fireplace Lights/switch
+
+Here is an example Home Assistant config:
+
+```yaml
+switch:
+  platform: mqtt
+  name: "Fireplace Lights"
+  state_topic: "/smartthings/Fireplace Lights/switch"
+  command_topic: "/smartthings/Fireplace Lights/switch"
+  brightness_state_topic: "/smartthings/Fireplace Lights/level"
+  brightness_command_topic: "/smartthings/Fireplace Lights/level"
+  payload_on: "on"
+  payload_off: "off"
+  retain: true
+```
+
+We recommend `retain: true` for every MQTT device in order to keep states in sync when things become disconnected.
+
+Start digging through the [MQTT Components][mqtt-ha] in Home Assistant to find which components map to the new events being published to MQTT.
+
+### Configuring with Docker-Compose
+
+Our personal prefernce for starting the whole suite of software is to use a single Docker-Compose file.
+
+Just create a file called docker-compose.yml like this:
+
+```yaml
+mqtt:
+    image: matteocollina/mosca
+    ports:
+        - 1883:1883
+
+mqttbridge:
+    image: stjohnjohnson/smartthings-mqtt-bridge
+    volumes:
+        - ./mqtt-bridge:/config
+    ports:
+        - 8080:8080
+    links:
+        - mqtt
+
+homeassistant:
+    image: balloob/home-assistant
+    ports:
+        - 80:80
+    volumes:
+        - ./home-assistant:/config
+        - /etc/localtime:/etc/localtime:ro
+    links:
+        - mqtt
+```
+
+This will start home-assistant, MQTT, and the Bridge, in dependency order. All config can reference the name of the docker container instead of localhost (e.g. mqtt for the broker host in Home Assistant).
+
+### Future Improvements
+- **Raspberry pi**: There is a lot of interest in getting this running on the Raspberry Pi. It only requires binaries compiled for ARM, so we plan to get ARM-compatible versions of the containers going at some point.
+- **Authentication for MQTT**: At the moment, the MQTT bridge doesn't understand how to authenticate to MQTT, so only unauthenticated MQTT is supported. This is mitigated to some degree if you use our Docker Compose config, because MQTT's port is not actually shared publicly.
+- **Authentication for MQTT Bridge**: Right now the bridge expects that anyone subscribing is the SmartThings hub. This could use proper authentication.
+
+
+[mosquitto]: http://mosquitto.org/
+[emqttd]: https://github.com/emqtt/emqttd
+[mosca]: http://www.mosca.io/
+[docker]: https://www.docker.com/
+[mosca-standalone]: https://github.com/mcollina/mosca#standalone
+[mqtt-bridge]: https://github.com/stjohnjohnson/smartthings-mqtt-bridge
+[ide-dt]: https://graph.api.smartthings.com/ide/devices
+[devicetype]: https://github.com/stjohnjohnson/smartthings-mqtt-bridge/blob/master/devicetypes/stj/mqtt-bridge.src/mqtt-bridge.groovy
+[ide-app]: https://graph.api.smartthings.com/ide/apps
+[smartapp]: https://github.com/stjohnjohnson/smartthings-mqtt-bridge/blob/master/smartapps/stj/mqtt-bridge.src/mqtt-bridge.groovy
+[mqtt-ha]: https://home-assistant.io/components/mqtt/