Add initial blueprint support

[balloob]

Blueprint support is experimental and not recommended yet for production. Config will change between releases. Plan is to announce at the Home Assistant Conference.

Proposed change

Add support for blueprints in Home Assistant. Blueprints allows users that configure their automations via YAML to create reusable automations, reducing the amount of configuration necessary. Blueprints can easily be shared with others.

This is only the very basics plus a little bit more. I have a lot more plans for this but that will be for future PRs. I have created a document with the features I want to have added next. If you want to help, hit me up on Discord. Any blueprint PR that implements something not on that list will probably not be considered at this time.

Example blueprint in config/blueprints/automation/balloob/test_event_service.yaml:

blueprint:
  name: Call service from event
  domain: automation 
  input:
    trigger_event:
    service_to_call:
trigger:
  platform: event
  event_type: !placeholder trigger_event
action:
  service: !placeholder service_to_call

And then an example automation configuration to use it:

automation:
  use_blueprint:
    path: balloob/test_event_service.yaml
    input:
      trigger_event: my_event
      service_to_call: light.turn_on

Do not post non-dev related questions on this PR please. They will be marked as spam. If you feel like expressing your emotion, use the emoji reaction button.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

[probot-home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as its been labeled with an integration (automation) you are listed as a codeowner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[MartinHjelmare]

This will create one executor job per domain. Maybe that's ok?

[pvizeli]

I learn on Supervisor: jobs with doing IO on disk - Parallel is bad and make it slower (just hit the disk) / doing IO on network/pipe/memory/process - Parallel gives a real boost (just not hit our system)

[balloob]

You're right, that's ugly. We should do it in 1 call.

[balloob]

Not going to fix it for MVP, as we only support automation right now.

[pvizeli]

Why not use attr and his nice slot=True feature?

[balloob]

dataclass is built-in and pretty much the same :)

[balloob]

I could add frozen=True here. Which is a similar feature.

[pvizeli]

For memory footprint, it would be better if we not need to extend the object at runtime.

[balloob]

This object will remain in memory for <1 second. From when it's imported till when it's send over the websocket API.

[MartinHjelmare]

Nice!