Last Modified 2006-05-24 by ben

Horde Policies

The idea of Horde Policy is to implement a replacement for the current prefs system, modeled after how Group Policy Objects work in a Microsoft Active Directory. Including a nice administrative GUI, meaning no more editing prefs.php files, and happier admins.

Visualization of a Horde Policy


|-- name

|-- targets

|   |-- target1

|   `-- target2

|-- app1 (ie, imp)

`-- app2 (ie, turba)


    |   |-- attribute-group2

    |   |   `-- attribute1

    |   |       `-- value

    |   `-- attribute2

    |       `-- value

    `-- attribute3

        `-- value

  • each app would have a policy.xml file defining what policy attributes are available.
    • A target can consist of one or more:
      • default (applies to entire installation)
      • horde application (including 'horde')
      • horde group
      • individual user
      • guest user
      • OU if using LDAP backend

This structure should be easy to cache when a given app is loaded. something like if (!isset($policy[$app])) { load $policy[$app] from xml } .

What would need to be done

  • build a Horde Policy manager to list, create, edit, delete, etc. policies.
    • Store Horde Policies in DB table(s)
      • horde_policy table(s)?
      • extend the datatree? The data structure fits perfectly with a few performance tweaks


In order to make Horde Policies as generic as possible, it's probably best to specify a new backend for them. Then we can write policy drivers for the various parts of Horde that might use them, such as Prefs.

I'm a big fan of the Datatree structure, slightly simplified, to hold the Policy information. The DataTree itself has proved not to scale very well, but I think by removing a few unneeded fields (for this application, at least), we can reduce the number of JOIN statements, and it should scale just fine. Another thing to think about is how many Horde Policies is a given site going to have? Probably no more than a handful on average.

Anyway, here's a new table structure idea:
















target_id  <-- uid, gid, app-name, or global/default

target_type  <-- 'uid', 'gid', 'app', or 'global'/'default'

We can get the attribute group structure from the XML file. No need to worry about storing it, just need to enforce that all attributes for a given app have unique names. If there are two attributes with the same name, we should use the last one found in the XML file.


At login, all applicable Policies should be loaded and cached. We should also try to do something to cache Policies for guest sessions.

Could we use Horde_Cache for this?

Other Thoughts

  • all $pref->getValue() calls could be handled on the backend by writing a Policy driver for the Prefs system, giving us a drop-in replacement.
    • we'd need a way to clearly define what happens if two Horde Policies have overlapping, conflicting settings.
    • there should be a default "root" policy, which cannot be detached from the root installation. This policy would be a site-wide policy that always exists.
    • Should we keep a history of who created or edited a policy? Can we use the history classes for this?
    • Hooks should definitely come into play somehow. Perhaps store the name of the hook function with the attribute, where there is no hook if this is null?


http://www.microsoft.com/technet/itsolutions/msit/security/grppolobjectmgmt.mspx - gives a good overview on how MS GPO's work, and a nice graphic that really helped me visualize the internal workings.

Cut & Paste from mailing list until I can better organize my thoughts

- with something like this in place I think it would make more and

more sense to move everything that's at all user-related in conf.php

files to this system. Things like "user capabilities" in both Horde

and IMP - they can even be locked (overridable = false?) by default,

but letting people easily manage them on a per-group basis, or

whatever, sounds very good to me.

Just brainstorming here, but we could even go a step further and use this type of system for all of the configs (except for maybe the very basic stuff, like authentication). Doing so would let different groups have different configs, which might be helpful for sites hosting for various groups.
If there were a way to manage, say, IMAP server configs, or other

backend configurations (sieve servers, etc.) using this system, that

would be even better.

Yes! We could put IMAP server configs, etc. in a GPO and assign to targets as necessary. Same way that printers can be assigned in an active directory. "group A uses this IMAP server, group B uses this other IMAP server, group C gets to specify their own IMAP server." The possibilities are endless! I love it!