How to enable/disable the RHDS10 services upon boot time on RHEL7

Issue

What problem/issue/behavior are you having trouble with? What do you expect to see?

• On RHDS9/RHEL6 we used chkconfig to enable or disable starting of Directory Servers at boot, for example:

  chkconfig dirsrv on
  chkconfig dirsrv off
  chkconfig --list | grep dirsrv
  

• On RHDS10/RHEL7 I cannot find how to do this. Init has been replaced by systemd. I found out that 'systemctl disable dirsrv@' works fine to disable an instance, but when I run 'systemctl enable dirsrv@' I get the following somewhat cryptic message:

  # systemctl enable dirsrv@<instance>
  The unit files have no [Install] section. 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, ...).