Configurate OpenLDAP in mirror mode replication

I am going to share some user account & directory with NFS among 2~3 servers. Traditionally we can use NFS+NIS solution, but I would like to try out NFS+LDAP+PAM/NSS plus OpenLDAP mirror mode replication.

For LDAP + PAM/NSS, please refer to my other article: LDAP + Samba PDC + PAM/NSS on Debian Lenny HOWTO

Add OpenLDAP mirror mode replication to existing server

Refer to OpenLDAP Software 2.4 Administrator's Guide: Replication, just add the following EXTRA setup to /etc/ldap/slapd.conf:

# Global section
serverID        1
loglevel        sync stats
moduleload      syncprov
rootdn          "cn=admin,dc=example,dc=com"
rootpw          CHANGE

# syncprov specific indexing
index entryCSN                          eq
index entryUUID                         eq

# syncrepl Provider for primary db
overlay syncprov
syncprov-checkpoint 100 10
syncprov-sessionlog 100

# syncrepl directive
syncrepl      rid=001
              provider=ldap://server2.example.com
              bindmethod=simple
              binddn="cn=admin,dc=example,dc=com"
              credentials=CHANGE
              searchbase="dc=dc=example,dc=com"
              schemachecking=on
              type=refreshAndPersist
              retry="60 +"

mirrormode on

Copy & paste this setup to your server2, change the serverID and provider accordingly.

My suggested procedure for deploy

Shutdown both master/slave OpenLDAP server with:

/etc/init.d/slapd stop
Backup existing LDAP database under home directory:

slapcat > ~/master.ldif
Transfer the master.ldif to slave server.
Transfer the master /etc/ldap/slapd.conf to slave server, and update it accordingly.
Flush and import existing LDAP database in slave server:

rm -rf /var/lib/ldap/* slapadd -l ~/master.ldif slapindex chown -Rf openldap:openldap /var/lib/ldap
Start master server, and then slave server with:

/etc/init.d/slapd start