alias_database might not be referenced to the actual file for some operating systems ( e.g. alpine )

[flybyray]

https://github.com/robertdebock/ansible-role-postfix/blob/dd9ab8cf53c4f320bb67a6d7d8b6c96ba28fd781/templates/main.cf.j2#L439

should most probably replaced by:

alias_database = hash:{{ postfix_alias_path }}