slapo-dynlist — Dynamic List overlay to slapd
ETCDIR/slapd.conf
The dynlist
overlay to slapd(8) allows expansion
of dynamic groups and more. Any time an entry with a specific
objectClass is being returned, the LDAP URI-valued
occurrences of a specific attribute are expanded into the
corresponding entries, and the values of the attributes
listed in the URI are added to the original entry. No
recursion is allowed, to avoid potential infinite loops. The
resulting entry must comply with the LDAP data model, so
constraints are enforced. For example, if a SINGLE-VALUE attribute is
listed, only the first value results in the final entry. The
above described behavior is disabled when the manageDSAit control (RFC
3296) is used. In that case, the contents of the dynamic
group entry is returned; namely, the URLs are returned
instead of being expanded.
The config directives that are specific to the dynlist overlay must be
prefixed by dynlist−, to avoid
potential conflicts with directives specific to the
underlying database or to other stacked overlays.
This directive adds the dynlist overlay to the current database, or to the frontend, if used before any database instantiation; see slapd.conf(5) for details.
This slapd.conf
configuration option is defined for the dynlist
overlay. It may have multiple occurrences, and it must
appear after the overlay directive.
The value <group-oc> is the
name of the objectClass that triggers the dynamic
expansion of the data.
The value <URL-ad> is the
name of the attributeDescription that contains the URI
that is expanded by the overlay; if none is present, no
expansion occurs. If the intersection of the attributes
requested by the search operation (or the asserted
attribute for compares) and the attributes listed in
the URI is empty, no expansion occurs for that specific
URI. It must be a subtype of labeledURI.
The value <member-ad> is
optional; if present, the overlay behaves as a dynamic
group: this attribute will list the DN of the entries
resulting from the internal search. In this case, the
<attrs> portion of the URI must be absent, and
the DNs of all the entries resulting from the expansion
of the URI are listed as values of this attribute.
Compares that assert the value of the <member-ad>
attribute of entries with <group-oc>
objectClass apply as if the DN of the entries resulting
from the expansion of the URI were present in the
<group-oc> entry
as values of the <member-ad>
attribute.
The dynlist overlay may be used with any backend, but it is mainly intended for use with local storage backends. In case the URI expansion is very resource-intensive and occurs frequently with well-defined patterns, one should consider adding a proxycache later on in the overlay stack.
By default the expansions are performed using the identity
of the current LDAP user. This identity may be overridden by
setting the dgIdentity attribute to the
DN of another LDAP user. In that case the dgIdentity will be
used when expanding the URIs in the object. Setting the
dgIdentity to a zero-length string will cause the expansions
to be performed anonymously. Note that the dgIdentity
attribute is defined in the dyngroup schema, and this
schema must be loaded before the dgIdentity authorization
feature may be used.
This example collects all the email addresses of a database into a single entry; first of all, make sure that slapd.conf contains the directives:
include /path/to/dyngroup.schema
# ...
database <database>
# ...
overlay dynlist
dynlist-attrset groupOfURLs memberURL
and that slapd loads dynlist.la, if compiled as a run-time module; then add to the database an entry like
dn: cn=Dynamic List,ou=Groups,dc=example,dc=com
objectClass: groupOfURLs
cn: Dynamic List
memberURL: ldap:///ou=People,dc=example,dc=com?mail?sub?(objectClass=person)
If no <attrs> are provided in the URI, all (non-operational) attributes are collected.
This example implements the dynamic group feature on the
member
attribute:
include /path/to/dyngroup.schema
# ...
database <database>
# ...
overlay dynlist
dynlist-attrset groupOfURLs memberURL member
A dynamic group with dgIdentity authorization could be created with an entry like
dn: cn=Dynamic Group,ou=Groups,dc=example,dc=com
objectClass: groupOfURLs
objectClass: dgIdentityAux
cn: Dynamic Group
memberURL: ldap:///ou=People,dc=example,dc=com??sub?(objectClass=person)
dgIdentity: cn=Group Proxy,ou=Services,dc=example,dc=com
slapd.conf(5), slapd(8). The slapo-dynlist(5) overlay
supports dynamic configuration via back-config.