OpenLDAP plugin missing important data

[quanah]

The OpenLDAP plugin to query back-monitor is leaving out some critical information that has been added in recent releases about the state of the LMDB backend if it is in use (I.e., back-mdb). Specifically these attribute value pairs:

olmMDBPagesMax: 262144
olmMDBPagesUsed: 629
olmMDBPagesFree: 58
olmMDBReadersMax: 126
olmMDBReadersUsed: 2
olmMDBEntries: 1005

Here's an example of a full LDAP entry from back monitor:

dn: cn=Database 1,cn=Databases,cn=Monitor
structuralObjectClass: monitoredObject
creatorsName:
modifiersName:
createTimestamp: 20200205235526Z
modifyTimestamp: 20200205235526Z
monitoredInfo: mdb
monitorIsShadow: FALSE
namingContexts: dc=example,dc=com
readOnly: FALSE
monitorOverlay: dynlist
olmMDBPagesMax: 262144
olmMDBPagesUsed: 629
olmMDBPagesFree: 58
olmMDBReadersMax: 126
olmMDBReadersUsed: 2
olmMDBEntries: 1005
olmDbDirectory: /var/lib/ldap/
entryDN: cn=Database 1,cn=Databases,cn=Monitor
subschemaSubentry: cn=Subschema
hasSubordinates: TRUE

[quanah]

In #6993

[quanah]

Output with my changes:

./telegraf -config /etc/telegraf/telegraf.conf -input-filter openldap -test --debug
2020-02-06T19:47:50Z I! Starting Telegraf
2020-02-06T19:47:50Z D! [agent] Initializing plugins
> openldap,host=anvil3.rb.symas.net,port=389,server=localhost connections_current=1i,connections_max_file_descriptors=1024i,connections_total=1222i,databases_database_1_mdb_entries=1005i,databases_database_1_mdb_pages_free=58i,databases_database_1_mdb_pages_max=262144i,databases_database_1_mdb_pages_used=629i,databases_database_1_mdb_readers_max=126i,databases_database_1_mdb_readers_used=2i,operations_abandon_completed=0i,operations_abandon_initiated=0i,operations_add_completed=0i,operations_add_initiated=0i,operations_bind_completed=9i,operations_bind_initiated=9i,operations_compare_completed=0i,operations_compare_initiated=0i,operations_delete_completed=0i,operations_delete_initiated=0i,operations_extended_completed=0i,operations_extended_initiated=0i,operations_modify_completed=0i,operations_modify_initiated=0i,operations_modrdn_completed=0i,operations_modrdn_initiated=0i,operations_search_completed=221i,operations_search_initiated=222i,operations_unbind_completed=11i,operations_unbind_initiated=11i,statistics_bytes=866834i,statistics_entries=10249i,statistics_pdu=10478i,statistics_referrals=0i,threads_active=1i,threads_backload=1i,threads_max=16i,threads_max_pending=0i,threads_open=2i,threads_pending=0i,threads_starting=0i,time_uptime=71544i,waiters_read=1i,waiters_write=0i 1581018470000000000