Configuring ClickHouse to use LDAP for authentication and role mapping

1. Test your connection to this public LDAP server:

   $ ldapsearch -x -b dc=example,dc=com -H ldap://ldap.forumsys.com

   The reply will be something like this:

   # extended LDIF
   #
   # LDAPv3
   # base <dc=example,dc=com> with scope subtree
   # filter: (objectclass=*)
   # requesting: ALL
   #
   
   # example.com
   dn: dc=example,dc=com
   objectClass: top
   objectClass: dcObject
   objectClass: organization
   o: example.com
   dc: example
   ...

2. Edit the config.xml file and add the following to configure LDAP:

   <ldap_servers>
       <test_ldap_server>
       <host>ldap.forumsys.com</host>
       <port>389</port>
       <bind_dn>uid={user_name},dc=example,dc=com</bind_dn>
       <enable_tls>no</enable_tls>
       <tls_require_cert>never</tls_require_cert>
       </test_ldap_server>
   </ldap_servers>

These are the basic settings used above:

3. Add the <ldap> section to <user_directories> section to configure the user role mapping. This section defines when a user is authenticated and what role the user will receive. In this basic example, any user authenticating to LDAP will receive the scientists_role which will be defined at a later step in ClickHouse. The section should look similar to this:

   <user_directories>
       <users_xml>
           <path>users.xml</path>
       </users_xml>
       <local_directory>
           <path>/var/lib/clickhouse/access/</path>
       </local_directory>
       <ldap>
             <server>test_ldap_server</server>
             <roles>
                <scientists_role />
             </roles>
             <role_mapping>
                <base_dn>dc=example,dc=com</base_dn>
                <search_filter>(&amp;(objectClass=groupOfUniqueNames)(uniqueMember={bind_dn}))</search_filter>
                <attribute>cn</attribute>
             </role_mapping>
       </ldap>
   </user_directories>

   These are the basic settings used above:

   Parameter	Description	Example
   server	label defined in the prior ldap_servers section	test_ldap_server
   roles	name of the roles defined in ClickHouse the users will be mapped to	scientists_role
   base_dn	base path to start search for groups with user	dc=example,dc=com
   search_filter	ldap search filter to identify groups to select for mapping users	(&(objectClass=groupOfUniqueNames)(uniqueMember={bind_dn}))
   attribute	which attribute name should value be returned from	cn

4. Restart your ClickHouse server to apply the settings.

1. Create a role in clickhouse with the same name used in the role mapping section of the config.xml file

   CREATE ROLE scientists_role;

2. Grant needed privileges to the role. The following statement grants admin privileges to any user able to authenticate through LDAP:

   GRANT ALL ON *.* TO scientists_role;

1. Login using the ClickHouse client

   $ clickhouse-client --user einstein --password password
   ClickHouse client version 22.2.2.1.
   Connecting to localhost:9000 as user einstein.
   Connected to ClickHouse server version 22.2.2 revision 54455.
   
   chnode1 :)

2. Test that the user was mapped correctly to the scientists_role role and has admin permissions

   SHOW DATABASES

   Query id: 93b785ff-1482-4eda-95b0-b2d68b2c5e0f
   
   ┌─name───────────────┐
   │ INFORMATION_SCHEMA │
   │ db1_mysql          │
   │ db2                │
   │ db3                │
   │ db4_mysql          │
   │ db5_merge          │
   │ default            │
   │ information_schema │
   │ system             │
   └────────────────────┘
   
   9 rows in set. Elapsed: 0.004 sec.