WantedBy=
relationship.
.
Most services that want to be started automatically at boot should use
WantedBy=multi-user.target
or WantedBy=graphical.target
.
Services that want to be started in rescue or single-user mode should
instead use WantedBy=sysinit.target
See-Also: https://wiki.debian.org/Teams/pkg-systemd/rcSMigration