Cannot enable ralph service with systemd

[Napsty]

Steps to reproduce

• Restart VM in which ralph runs
• ralph is not automatically started
• systemctl enable ralph returns an error

Expected behavior

We can use systemctl enable ralph so ralph is automatically started after boot.

Actual behavior

systemctl enable ralph returns an error:

root@ralph:~# systemctl enable ralph.service
The unit files have no installation config (WantedBy, RequiredBy, Also, Alias
settings in the [Install] section, and DefaultInstance for template units).
This means they are not meant to be enabled using systemctl.
Possible reasons for having this kind of units are:
1) A unit may be statically enabled by being symlinked from another unit's
   .wants/ or .requires/ directory.
2) A unit's purpose may be to act as a helper for some other unit which has
   a requirement dependency on it.
3) A unit may be started when needed via activation (socket, path, timer,
   D-Bus, udev, scripted systemctl call, ...).
4) In case of template units, the unit is meant to be enabled with some
   instance name specified.

Environment

• Ralph version: 20211112.1
• Operating system: Ubuntu 18.04.6
• Method of installation: Deb package? Manual installation? Docker? Deb (APT repository)