CI servicesn not working - on k8s Group Runners

I’m trying to run a postgres service
but I’m unable to connect to it error: getaddrinfo ENOTFOUND postgres postgres:5432
unit tests:
services:
- postgres:12.2-alpine
variables:
POSTGRES_DB: test_db
POSTGRES_USER: runner
POSTGRES_PASSWORD: ‘’
POSTGRES_HOST_AUTH_METHOD: trust

Should I configure something on my runner? this is not a shared runner