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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 (defined in the overlay configuration) is being
returned, the LDAP URI-valued occurrences of a specific
attribute (also defined in the overlay configuration) 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.
Since the resulting entry is dynamically constructed, it does not exist until it is constructed while being returned. As a consequence, dynamically added attributes do not participate in the filter matching phase of the search request handling. In other words, filtering for dynamically added attributes always fails.
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 found during the list
expansion appears 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 optional URI
restricts expansion only to entries matching the
DN, the scope and the
filter
portions of the URI.
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 URIs in the URL-ad attribute must
be absent, and the DNs of
all the entries resulting from the expansion of the
URIs 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.
Alternatively, mapped-ad can be used
to remap attributes obtained through expansion.
member-ad
attributes are not filled by expanded DN, but are
remapped as mapped-ad attributes.
Multiple mapping statements can be used.
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 in the
group's entry 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. If the dgAuthz attribute is also
present in the group's entry, its values are used to
determine what identities are authorized to use the
dgIdentity to
expand the group. Values of the dgAuthz attribute must
conform to the (experimental) OpenLDAP authz syntax.
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-config(5), slapd(8). The slapo-dynlist(5) overlay
supports dynamic configuration via back-config.