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Integration Configuration via YAML

configuration.yaml is a configuration file defined by the user. It is automatically created by Home Assistant on first launch. It defines which components to load.

Note about YAML for devices and/or services

Integrations that communicate with devices and/or services are configured via a config flow. In rare cases, we can make an exception. Existing integrations that should not have a YAML configuration are allowed and encouraged to implement a configuration flow and remove YAML support. Changes to existing YAML configuration for these same existing integrations will no longer be accepted.

For more detail read ADR-0010

Pre-processing​

Home Assistant will do some pre-processing on the config based on the components that are specified to load.

CONFIG_SCHEMA​

If a component defines a variable CONFIG_SCHEMA, the config object that is passed in will be the result of running the config through CONFIG_SCHEMA. CONFIG_SCHEMA should be a voluptuous schema.

PLATFORM_SCHEMA​

If a component defines a variable PLATFORM_SCHEMA, the component will be treated as an entity component. The configuration of entity components is a list of platform configurations.

Home Assistant will gather all platform configurations for this component. It will do so by looking for configuration entries under the domain of the component (ie light) but also under any entry of domain + extra text.

While gathering the platform configs, Home Assistant will validate them. It will see if the platform exists and if the platform defines a PLATFORM_SCHEMA, validate against that schema. If not defined, it will validate the config against the PLATFORM_SCHEMA defined in the component. Any configuration that references non existing platforms or contains invalid config will be removed.

The following configuration.yaml:

unrelated_component:
  some_key: some_value

switch:
  platform: example1

switch living room:
  - platform: example2
    some_config: true
  - platform: invalid_platform

will be passed to the component as

{
    "unrelated_component": {
        "some_key": "some_value"
    },
    "switch": [
        {
            "platform": "example1"
        },
        {
            "platform": "example2",
            "some_config": True
        }
    ],
}