This project provides a Hass.io addon around signal-cli-rest-api for use with the Signal Messenger integration
On first startup you will need to register a number, and verify it with the SMS code. If you use all the defaults, then something like the following should get things set up.
curl -X POST -H "Content-Type: application/json" \
'http://hassio:8080/v1/register/+61234567890'
curl -X POST -H "Content-Type: application/json" \
'http://hassio:8080/v1/register/+61234567890/verify/123-456'
After the initial verification, you should be able to use http://127.0.0.1:8080
in your Home Assistant configuration for Signal.