Historically if you integrated Google Assistant with Home Assistant every time you asked "Hey Google, switch the light off" your Google device would do this:

"Hey Google" > Google Cloud > Public Internet > Home Assistant

We want it to do this:

"Hey Google" > Home Assistant

Assuming you already have the google_assistant: integration setup

  1. Open the project you created in the Actions on Google console.
  2. Click Develop on the top of the page, then click Actions located in the hamburger menu on the top left.
  3. Upload app.js from here for both Node and Chrome by clicking the Upload Javascript files button.
  4. Add device scan configuration:
  5. Click + New scan config if no configuration exists
  6. Select MDNS
  7. Set MDNS service name to _home-assistant._tcp.local
  8. Click Add field, then under Select a field choose Name
  9. Enter a new Value field set to .*\._home-assistant\._tcp\.local
  10. Check the box Support local query under Add capabilities.
  11. Save your changes.
  12. Either wait for 30 minutes, or restart all your Google Assistant devices.
  13. Restart Home Assistant Core.
  14. With a Google Assistant device, try saying “OK Google, sync my devices.” This can be helpful to avoid issues, especially if you are enabling local fulfillment sometime after adding cloud Google Assistant support.

Alternatively, Home Assistant Cloud will configure this all for you automatically