Unique attributes in OpenDJ

Sometimes you need to set some attributes as unique, for example: if LDAP contains system users, then uid attribute shouldn’t repeat in whole system.
OpenDJ is equipped with proper plugin, but it’s not enabled by default. In case of mail system, attribute mail should be unique. Here we don’t have ready to use plugin, but we can easily create it basing on UID Unique Attribute and this description and this one.

But I didn’t make this post to send you to other pages. I would like to show you how to add Plugin with dsconfig and how to copy it to replica with LDIF export/import.

root@ldapdj1:~# dsconfig -D cn=dirmgr -h localhost -p 4444 -X
>>>> Specify OpenDS LDAP connection parameters

Password for user 'cn=dirmgr': 

>>>> OpenDS configuration console main menu

What do you want to configure?

    1)   Access Control Handler               23)  Log Rotation Policy
    2)   Account Status Notification Handler  24)  Matching Rule
    3)   Administration Connector             25)  Monitor Provider
    4)   Alert Handler                        26)  Network Group
    5)   Attribute Syntax                     27)  Network Group QOS Policy
    6)   Backend                              28)  Password Generator
    7)   Certificate Mapper                   29)  Password Policy
    8)   Connection Handler                   30)  Password Storage Scheme
    9)   Crypto Manager                       31)  Password Validator
    10)  Debug Target                         32)  Plugin
    11)  Entry Cache                          33)  Plugin Root
    12)  Extended Operation Handler           34)  Replication Domain
    13)  Extension                            35)  Replication Server
    14)  External Changelog Domain            36)  Root DN
    15)  Global Configuration                 37)  Root DSE Backend
    16)  Group Implementation                 38)  SASL Mechanism Handler
    17)  Identity Mapper                      39)  Synchronization Provider
    18)  Key Manager Provider                 40)  Trust Manager Provider
    19)  Local DB Index                       41)  Virtual Attribute
    20)  Local DB VLV Index                   42)  Work Queue
    21)  Log Publisher                        43)  Workflow
    22)  Log Retention Policy                 44)  Workflow Element

    q)   quit

Enter choice: 32


>>>> Plugin management menu

What would you like to do?

    1)  List existing Plugins
    2)  Create a new Plugin
    3)  View and edit an existing Plugin
    4)  Delete an existing Plugin

    b)  back
    q)  quit

Enter choice [b]: 1


Plugin                             : Type                            : enabled
-----------------------------------:---------------------------------:--------
7-Bit Clean                        : seven-bit-clean                 : false
Change Number Control              : change-number-control           : true
Entry UUID                         : entry-uuid                      : true
Fractional Replication LDIF Import : fractional-ldif-import          : true
LastMod                            : last-mod                        : true
LDAP Attribute Description List    : ldap-attribute-description-list : true
Password Policy Import             : password-policy-import          : true
Profiler                           : profiler                        : true
Referential Integrity              : referential-integrity           : false
UID Unique Attribute               : unique-attribute                : false

As you can see above, the UID Unique Attribute plugin is not enabled. To enable it you just need to set enable to true. I will omit this step, let’s make a new plugin:

What would you like to do?

    1)  List existing Plugins
    2)  Create a new Plugin
    3)  View and edit an existing Plugin
    4)  Delete an existing Plugin

    b)  back
    q)  quit

Enter choice [b]: 2


>>>> Select the type of Plugin that you want to create:

    1)  Change Number Control Plugin          7)   Password Policy Import
                                                   Plugin
    2)  Entry UUID Plugin                     8)   Profiler Plugin
    3)  Fractional LDIF Import Plugin         9)   Referential Integrity
                                                   Plugin
    4)  Last Mod Plugin                       10)  Seven Bit Clean Plugin
    5)  LDAP Attribute Description List       11)  Unique Attribute Plugin
        Plugin                                     
    6)  Network Group Plugin                       

    ?)  help
    c)  cancel
    q)  quit

Enter choice : 11


>>>> Enter a name for the Unique Attribute Plugin that you want to create: Mail Unique Attribute


>>>> Configuring the "enabled" property

    Indicates whether the plug-in is enabled for use.

Select a value for the "enabled" property:

    1)  true
    2)  false

    ?)  help
    c)  cancel
    q)  quit

Enter choice : 1


>>>> Configuring the "type" property

    Specifies the type of attributes to check for value uniqueness.

    Syntax:  OID

Enter a value for the "type" property: mail

Enter another value for the "type" property [continue]: 


>>>> Configure the properties of the Unique Attribute Plugin

        Property  Value(s)
        -----------------------------------------------------------------------
    1)  base-dn   The plug-in uses the server's public naming contexts in the
                  searches.
    2)  enabled   true
    3)  type      mail

    ?)  help
    f)  finish - create the new Unique Attribute Plugin
    c)  cancel
    q)  quit

Enter choice [f]: 

The Unique Attribute Plugin was created successfully

Press RETURN to continue 

Simple and intuitive, but I would like to pay attention that:

  • you can create plugins for your own attributes, even when added to OpenDJ as schema extension
  • attributes for which unique plugin is enable should be indexed for equality (eq)

If Multi-Master replication is configured you need to add also these plugins to second server. You can do this with dsconfig in interactive or non-interactive mode, but I think it will be faster and simpler with LDIF export/import. You can connect to LDAP with control-panel or other tool. Personally I’m using Eclipse with LDAP plugin, which I’m connecting to 4444 SSL port with base DN of cn=config. Now select proper branch cn=Plugins,cn=config, choose cn=Mail Unique Attribute and export to LDIF which be saved to disk as Mail-unique.ldif:

# cat Mail-unique.ldif
version: 1

dn: cn=Mail Unique Attribute,cn=Plugins,cn=config
objectClass: ds-cfg-unique-attribute-plugin
objectClass: ds-cfg-plugin
objectClass: top
cn: Mail Unique Attribute
ds-cfg-enabled: true
ds-cfg-java-class: org.opends.server.plugins.UniqueAttributePlugin
ds-cfg-plugin-type: postoperationadd
ds-cfg-plugin-type: postoperationmodify
ds-cfg-plugin-type: postoperationmodifydn
ds-cfg-plugin-type: postsynchronizationadd
ds-cfg-plugin-type: postsynchronizationmodify
ds-cfg-plugin-type: postsynchronizationmodifydn
ds-cfg-plugin-type: preoperationadd
ds-cfg-plugin-type: preoperationmodify
ds-cfg-plugin-type: preoperationmodifydn
ds-cfg-type: mail

Upload LDIF file to second server and import:

# ldapmodify -a -D cn=dirmgr -h localhost -X -f Mail-unique.ldif
Password for user 'cn=dirmgr':
Processing ADD request for cn=Mail Unique Attribute,cn=Plugins,cn=config
ADD operation successful for DN cn=Mail Unique Attribute,cn=Plugins,cn=config

You can also do this with GUI connected to second server, but I wanted to show you how to do this manually 🙂

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