All automations are made up of a trigger and an action. Optionally combined with a condition. Take for example the automation:
When Paulus arrives home and it is after sunset: Turn the lights on in the living room.”.
We can break up this automation into the following three parts:
(trigger) When Paulus arrives home (condition) and it is after sunset: (action) Turn the lights on in the living room
The first part is the trigger of the automation rule. Triggers describe events that should trigger the automation rule. In this case, it is a person arriving home, which can be observed in Home Assistant by observing the state of Paulus changing from ‘not_home’ to ‘home’.
The second part is the condition. Conditions are optional tests that can limit an automation rule to only work in your specific use cases. A condition will test against the current state of the system. This includes the current time, devices, people and other things like the sun. In this case, we only want to act when the sun has set.
The third part is the action, which will be performed when a rule is triggered and all conditions are met. For example, it can turn a light on, set the temperature on your thermostat or activate a scene.
Automation rules interact directly with the internal state of Home Assistant, so you’ll need to familiarize yourself with it. Home Assistant exposes its current state via the developer tools. These are available at the bottom of the sidebar in the frontend. Developer Tools -> States will show all currently available states. An entity can be anything. A light, a switch, a person and even the sun. A state consists of the following parts:
|Entity ID||Unique identifier for the entity.||
|State||The current state of the device.||
|Attributes||Extra data related to the device and/or current state.||
State changes can be used as the source of triggers and the current state can be used in conditions.
Actions are all about calling services. To explore the available services open the Developer Tools -> Services. Services allow changing anything. For example turn on a light, run a script or enable a scene. Each service has a domain and a name. For example the service
light.turn_on is capable of turning on any light in your system. Services can be passed parameters to for example tell which device to turn on or what color to use.
Now that you’ve got a sneak peek of what is possible, it’s time to get your feet wet and create your first automation.