If you are just using the notify.alexa_media service, you need the target argument. This should be an array of the target devices. You can use the friendly name, entity id or a Home Assistant group).
If you want to easily send the notification to all devices, there are a couple of ways.
Using a Home Assistant Group
Create a group in Home Assistant, containing all your Alexa devices.
Call the notify.alexa_media service as follows (assuming your group is named group.alexa:
{
"data": {
"method": "speak",
"type": "announce",
"target":["group.alexa"]
},
"message": "There is motion at the Entry Gate"
}
Using an Alexa Multi Speaker Group
Create a multi speaker group in Alexa, containing all the devices. You may need to restart Home Assistant to pick up the new group.
You should now find a new service, named like notify.alexa_media_groupname (e.g. notify.alexa_media_everywhere).
Since this service automatically targets a particular group, you don’t need the target argument, and can just call it with your original JSON:
{
"data": {
"method": "speak",
"type": "announce"
},
"message": "There is motion at the Entry Gate"
}
This is the method I prefer as, once the new groups have been picked up by the component, everything can be managed in the Alexa app and you shouldn’t need to restart Home Assistant.
This also allows you to limit notifications to different parts of the house. For example, you could have Everywhere, Upstairs, and Downstairs groups and use the notify.alexa_media_everywhere, notify.alexa_media_upstairs, or notify.alexa_media_downstairs services depending on which devices you want the announcement to come from.
