Installing custom ldap schema 6.0
Introduction
When extending ZCS, it is sometimes desirable to add additional LDAP schema to the OpenLDAP server shipped with ZCS. Starting with the 6.0 release, the new config backend is used, which means that the traditional *.schema files are no longer in play. Instead, LDIF-based versions of the old schema files are used by the new config backend. This means that traditional "schema" files need to be converted to the new LDIF format for ZCS to be able to use them.
New layout of the schema directory
It is important to understand how the new LDIF based schema files are used by the cn=config directory. To start, let's examine the contents of the directory:
ls /opt/zimbra/data/ldap/config/cn\=config/cn\=schema cn={0}core.ldif cn={1}cosine.ldif cn={2}inetorgperson.ldif cn={3}zimbra.ldif cn={4}amavisd.ldif
As you can see there are multiple *.ldif files. The {#} format indicates the load order of the files in the cn=schema directory. I.e., cn={3}zimbra.ldif would be the fourth file loaded. Zimbra reserves the first 10 slots (cn={0}... to cn=(9)) for internal use. OpenLDAP will operate correctly even if the entire load sequence is not fully populated (i.e., if it goes from cn={4} to cn={10} with no schema in between). So when adding new custom schema, be sure to number them outside the {0} to {9} range, or problems may occur in the future.
Installing schema that are already converted
Some of the additional schema files shipped with OpenLDAP have already been converted into the LDIF-schema format, such as the one used by NIS services. This makes installing them a bit simpler, but it still takes a few steps:
cp /opt/zimbra/openldap/etc/openldap/schema/nis.ldif /opt/zimbra/data/ldap/config/cn\=config/cn\=schema
ldap stop ldap start
Converting schema to the new LDIF format
Fortunately, a utility to convert the old schema files to the new LDIF format is shipped with the ZCS OpenLDAP build, and the conversion process is fairly trivial. It consists of creating a temporary configuration file to load the old schema, and specifying a path to write out the new file, using the slaptest binary to do the conversion. Depending on the schema file needing conversion, it may be necessary to load additional schema files as part of the process.
For example, to convert the Samba 3.3 schema into an LDIF-format for use with ZCS, one would do the following:
mkdir -p /tmp/ldap/schema cd /tmp/ldap cp /path/to/samba.schema /tmp/ldap/schema
Create a file called "test.conf" with the following contents
include /opt/zimbra/openldap/etc/openldap/schema/core.schema include /opt/zimbra/openldap/etc/openldap/schema/cosine.schema include /opt/zimbra/openldap/etc/openldap/schema/inetorgperson.schema include /tmp/ldap/schema/samba.schema
Then execute
/opt/zimbra/openldap/sbin/slaptest -f /tmp/ldap/test.conf -F /tmp/ldap
This will create a new "cn=config" directory in /tmp/ldap. If you examine it's contents, you'll see:
ls cn\=config cn=schema cn=schema.ldif olcDatabase={0}config.ldif olcDatabase={-1}frontend.ldif
Note the cn=schema directory. This directory will contain the converted files, so lets go there:
cd cn\=config/cn\=schema ls cn={0}core.ldif cn={1}cosine.ldif cn={2}inetorgperson.ldif cn={3}samba.ldif
As you can see, there is now a samba.ldif file, which is what has been converted from the Samba schema file. The {#} format indicates the load order of the files in the cn=schema directory. I.e., cn={3}samba.ldif would be the fourth file loaded. However, ZCS itself already ships with a number of files to be loaded in this directory, so we'll need to renumber the cn={3}samba.ldif file. Zimbra reserves the first 10 slots (cn={0}... to cn=(9)) for internal use. OpenLDAP will operate correctly even if the entire load sequence is fully populated (i.e., if it goes from cn={4} to cn={10} with no schema in between).
The cn={3}samba.ldif file will need to be moved out of the ZCS reserved range given the above notes. To do this, we need to rename it and then modify it. So:
mv cn\=\{3\}samba.ldif cn\=\{10\}samba.ldif
The modify it so that the following lines are changed from:
dn: cn={3}samba objectClass: olcSchemaConfig cn: {3}samba
to
dn: cn={10}samba objectClass: olcSchemaConfig cn: {10}samba
To finish, we need to copy the new file in to the ZCS OpenLDAP schema directory, as the zimbra user:
cp /tmp/ldap/cn\=config/cn\=schema/cn\=\{10\}samba.ldif /opt/zimbra/data/ldap/config/cn\=config/cn\=schema ldap stop ldap start
Done!