MemberOf Multiple Grouping Enhancements


Overview

The idea is to allow multiple grouping attributes to be configured to automatically maintain a single memberOf attribute. In the following example, the member and uniqueMember attributes are configured as grouping attributes, both of which will trigger the memberOf attribute to be maintained:

dn: cn=usergroup,dc=example
member: cn=user1,dc=example

dn: cn=othergroup,dc=example
uniqueMember: cn=user2,dc=example

dn: cn=user1,dc=example
memberOf: cn=usergroup,dc=example

dn: cn=user2,dc=example
memberOf: cn=othergroup,dc=example

Corner Cases

The previous example is very straightforward, but there are some other cases that may seem a bit odd, so client applications will need to expect them. One of these odd cases is where a group entry refers to the same member entry by more than one grouping attribute. Consider the following example:

dn: cn=group,dc=example
member: cn=user,dc=example
memberPerson: cn=user,dc=example

dn: cn=user,dc=example
memberOf: cn=group,dc=example

In the above example, the client needs to understand that it can’t tell what type of grouping attribute was used to cause an entry to belong to a group by simply looking at the member entry. The member entry also provides no indication of being a member of a group entry in multiple ways (by the use of multiple grouping attributes). This example may not be a common or useful case, but it is something that could happen if the objectClasses on a group entry allow more than one of the configured group attributes.

Plug-In Configuration

It is preferred to keep the plug-in configuration backwards compatible to prevent breaking existing deployments during upgrade. This is easily done by simply allowing the memberOfGroupAttr attribute to have multiple values. Here is an example:

dn: cn=MemberOf Plugin,cn=plugins,cn=config
...
memberofgroupattr: member
memberofgroupattr: uniqueMember
memberofattr: memberOf

It is important to note that an attribute used as a memberOfGroupAttr must be defined with either the Distinguished Name or Name and Optional UID syntaxes. An attempt to use an attribute defined with any other syntax will be rejected.

Plug-In Changes

The memberOf plug-in needs to have a number of changes to support multiple grouping attributes. These changes are listed below:

Some of these cases may be dealt with by the current logic since we already handle cases such as an entry being a member of a group through multiple paths (this can occur from nested membership). We should check if the existing logic is sufficient before writing new code for these cases.

Last modified on 7 August 2014