There are two reasons for the plugin framework:
1. To provide a way of doing manual/complex LDAP changes without having
to keep extending ldapupdate.py (like we did with managed entries).
2. Allows for better control of restarts.
There are two types of plugins, preop and postop. A preop plugin runs
before any file-based updates are loaded. A postop plugin runs after
all file-based updates are applied.
A preop plugin may update LDAP directly or craft update entries to be
applied with the file-based updates.
Either a preop or postop plugin may attempt to restart the dirsrv instance.
The instance is only restartable if ipa-ldap-updater is being executed
as root. A warning is printed if a restart is requested for a non-root
user.
Plugins are not executed by default. This is so we can use ldapupdate
to apply simple updates in commands like ipa-nis-manage.
https://fedorahosted.org/freeipa/ticket/1789https://fedorahosted.org/freeipa/ticket/1790https://fedorahosted.org/freeipa/ticket/2032
