Failed to start OpenLDAP Server Daemon

1.service slapd start报错如下：

[root@DEV openldap]# systemctl status slapd.service
● slapd.service - OpenLDAP Server Daemon
Loaded: loaded (/usr/lib/systemd/system/slapd.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since 一 2019-06-24 19:33:50 CST; 3min 50s ago
Docs: man:slapd
man:slapd-config
man:slapd-hdb
man:slapd-mdb
file:///usr/share/doc/openldap-servers/guide.html
Process: 41179 ExecStart=/usr/sbin/slapd -u ldap -h ${SLAPD_URLS} $SLAPD_OPTIONS (code=exited, status=1/FAILURE)
Process: 41164 ExecStartPre=/usr/libexec/openldap/check-config.sh (code=exited, status=0/SUCCESS)

6月 24 19:33:50 DEV-SupplyChain-App01 check-config.sh[41164]: Checking configuration file failed:
6月 24 19:33:50 DEV-SupplyChain-App01 check-config.sh[41164]: /etc/openldap/slapd.conf: line 132: index attribute "loginShell" undefined
6月 24 19:33:50 DEV-SupplyChain-App01 check-config.sh[41164]: slaptest: bad configuration file!
6月 24 19:33:50 DEV-SupplyChain-App01 slapd[41179]: @(#) $OpenLDAP: slapd 2.4.44 (Jan 29 2019 17:42:45) $
mockbuild@x86-01.bsys.centos.org:/builddir/build/BUILD/openldap-2.4.44/openldap-2.4.44/servers/slapd
6月 24 19:33:50 DEV-SupplyChain-App01 slapd[41179]: /etc/openldap/slapd.conf: line 132: index attribute "loginShell" undefined
6月 24 19:33:50 DEV-SupplyChain-App01 slapd[41179]: DIGEST-MD5 common mech free
6月 24 19:33:50 DEV-SupplyChain-App01 systemd[1]: slapd.service: control process exited, code=exited status=1
6月 24 19:33:50 DEV-SupplyChain-App01 systemd[1]: Failed to start OpenLDAP Server Daemon.
6月 24 19:33:50 DEV-SupplyChain-App01 systemd[1]: Unit slapd.service entered failed state.
6月 24 19:33:50 DEV-SupplyChain-App01 systemd[1]: slapd.service failed.

2.可能是CentOS的版本或其他配置导致，CentOS版本如下

CentOS Linux release 7.6.1810 (Core)

3.通过Start LDAP server in debug mode解决

slapd -d 2 -F /etc/openldap/slapd.d/ -u ldap

4.参考文章：http://emmanuel.iffly.free.fr/doku.php?id=ldap:openldap2.4_centos