# $OpenLDAP$
# Copyright 2007-2021 The OpenLDAP Foundation, All Rights Reserved.
# COPYING RESTRICTIONS APPLY, see COPYRIGHT.

H1: Upgrading from 2.4.x

The following sections attempt to document the steps you will need to take in order 
to upgrade from the latest 2.4.x OpenLDAP version.

The normal upgrade procedure, as discussed in the {{SECT:Maintenance}} section, should 
of course still be followed prior to doing any of this.

H2: {{B:cn=config}} olc* attributes

H2: ppolicy overlay

The overlay now implements version 10 of the ppolicy draft in full. This includes the notion of a password
administrator where applicable (as determined by having a {{manage}} permission to the {{userPassword}} attribute)
and skips certain processing when there is no valid policy in effect or where the operation is initiated by
a password administrator. Many attributes are now tagged with {{NO-USER-MODIFICATION}} in the schema, requiring
the use of {{relax}} control to modify them.

In OpenLDAP 2.4 the {{slapo-ppolicy}}(5) overlay relied on a separate schema file to be included for it to function.
This schema is now implemented internally in the slapo-ppolicy module. When upgrading {{slapd.conf}}(5) deployments
the include statement for the schema must be removed.  For {{slapd-config}}(5) deployments, the config database
must be exported via slapcat and the old ppolicy schema removed from the export.  The resulting config database
can then be imported.

H2: unique overlay

In OpenLDAP 2.4 it was possible to bypass {{slapo-unique}}(5) checks by using the manageDSAIT control as a part of the
request. This is no longer possible. To achieve the same functionality the relax control must be used instead, and the
binding identity must have manage permissions on the entry being modified.

With OpenLDAP 2.5 a new keyword "serialize" has been added as a part of the unique_uri configuration parameter. This
will cause all write operations requiring uniqueness to be serialized so as to avoid the scenario where multiple
concurrent updates can prevent uniqueness from being enforced. See the {{slapo-unique}}(5) man page for further details.

H2: ldap and meta backends

Several deprecated configuration directives for {{slapd-ldap}}(5) and {{slapd-meta}}(5) have been removed. Configurations
using those directive must be updated to use supported directives prior to upgrade.  See the {{slapd-ldap}}(5) and
{{slapd-meta}}(5) man pages from OpenLDAP 2.4 for a list of deprecated directives.

H2: shell backend

This deprecated backend has been removed from OpenLDAP 2.5. Configurations making use of this backend must remove it
prior to upgrade. The {{slapd-sock}}(5) backend is recommended as an alternative.

H2: perl and sql backends

The {{slapd-perl}}(5) and {{slapd-sql}}(5) backends are now deprecated and no longer automatically enabled with
the --enable-backends configure flag.

H2: hdb and bdb backends

The Berkeley DB based slapd-bdb and slapd-hdb backends have been removed from OpenLDAP 2.5. Deployments making use
of these backends must migrate their configurations to use {{slapd-mdb}}(5) prior to upgrade.

H2: mdb backend

Due to database format changes between OpenLDAP 2.4 and OpenLDAP 2.5 it is mandatory for existing {{slapd-mdb}}(5) databases
to be exported via an OpenLDAP 2.4 slapcat prior to upgrade. They must then be reloaded via an OpenLDAP 2.5 slapadd after
the binaries are updated. It is also advised to determine if the new {{slapd-mdb}}(5) idlexp backend directive and/or
the multival database directive should be added to the OpenLDAP 2.5 configuration prior to import.