• Security
  • User deletion
• Git password authentication
• Enabling LDAP sign-in for existing GitLab users
• Google Secure LDAP
• Configuration
  • Example Configurations
  • Basic Configuration Settings
    • Examples of user filters
  • SSL Configuration Settings
  • Attribute Configuration Settings
  • LDAP Sync Configuration Settings
  • Set up LDAP user filter
    • Escaping special characters
  • Enabling LDAP username lowercase
  • Disable LDAP web sign in
  • Using encrypted credentials
• Encryption
  • TLS Server Authentication
  • Limitations
    • TLS Client Authentication
• Multiple LDAP servers
• User sync
  • Adjusting LDAP user sync schedule
• Group Sync
  • Adding group links
  • Administrator sync
  • Global group memberships lock
  • Adjusting LDAP group sync schedule
  • External groups
  • Group sync technical details
    • Supported LDAP group types/attributes
      • Nested group memberships
    • Queries
    • Benchmarks
• Troubleshooting

General LDAP setup

GitLab integrates with LDAP to support user authentication.

This integration works with most LDAP-compliant directory servers, including:

• Microsoft Active Directory
  • Microsoft Active Directory Trusts are not supported.
• Apple Open Directory
• Open LDAP
• 389 Server

Users added through LDAP take a licensed seat.

GitLab Enterprise Editions (EE) include enhanced integration, including group membership syncing and multiple LDAP server support.

Security

GitLab assumes that LDAP users:

• Are not able to change their LDAP mail, email, or userPrincipalName attributes. An LDAP user allowed to change their email on the LDAP server can potentially take over any account on your GitLab server.
• Have unique email addresses. If not, it’s possible for LDAP users with the same email address to share the same GitLab account.

We recommend against using LDAP integration if your LDAP users are allowed to change their mail, email or userPrincipalName attributes on the LDAP server, or share email addresses.

User deletion

Users deleted from the LDAP server are immediately blocked from signing in to GitLab. However, there’s an LDAP check cache time of one hour (which is configurable for GitLab Premium users). This means users already signed-in or who are using Git over SSH can access GitLab for up to one hour. Manually block the user in the GitLab Admin Area to immediately block all access.

Git password authentication

LDAP-enabled users can authenticate with Git using their GitLab username or email and LDAP password, even if password authentication for Git is disabled in the application settings.

Enabling LDAP sign-in for existing GitLab users

When a user signs in to GitLab with LDAP for the first time and their LDAP email address is the primary email address of an existing GitLab user, the LDAP DN is associated with the existing user. If the LDAP email attribute isn’t found in the GitLab user database, a new user is created.

In other words, if an existing GitLab user wants to enable LDAP sign-in for themselves, they should check that their GitLab email address matches their LDAP email address, and then sign into GitLab by using their LDAP credentials.

Google Secure LDAP

Google Cloud Identity provides a Secure LDAP service that can be configured with GitLab for authentication and group sync. See Google Secure LDAP for detailed configuration instructions.

Configuration

To enable LDAP integration you need to add your LDAP server settings in /etc/gitlab/gitlab.rb or /home/git/gitlab/config/gitlab.yml for Omnibus GitLab and installations from source respectively.

There is a Rake task to check LDAP configuration. After configuring LDAP using the documentation below, see LDAP check Rake task for information on the LDAP check Rake task.

LDAP users must have a set email address, regardless of whether or not it’s used to sign in.

Example Configurations

Omnibus Configuration

gitlab_rails['ldap_enabled'] = true
gitlab_rails['prevent_ldap_sign_in'] = false
gitlab_rails['ldap_servers'] = {
'main' => {
  'label' => 'LDAP',
  'host' =>  'ldap.mydomain.com',
  'port' => 389,
  'uid' => 'sAMAccountName',
  'encryption' => 'simple_tls',
  'verify_certificates' => true,
  'bind_dn' => '_the_full_dn_of_the_user_you_will_bind_with',
  'password' => '_the_password_of_the_bind_user',
  'verify_certificates' => true,
  'tls_options' => {
    'ca_file' => '',
    'ssl_version' => '',
    'ciphers' => '',
    'cert' => '',
    'key' => ''
  },
  'timeout' => 10,
  'active_directory' => true,
  'allow_username_or_email_login' => false,
  'block_auto_created_users' => false,
  'base' => 'dc=example,dc=com',
  'user_filter' => '',
  'attributes' => {
    'username' => ['uid', 'userid', 'sAMAccountName'],
    'email' => ['mail', 'email', 'userPrincipalName'],
    'name' => 'cn',
    'first_name' => 'givenName',
    'last_name' => 'sn'
  },
  'lowercase_usernames' => false,

  # EE Only
  'group_base' => '',
  'admin_group' => '',
  'external_groups' => [],
  'sync_ssh_keys' => false
  }
}

Source Configuration

production:
  # snip...
  ldap:
    enabled: false
    prevent_ldap_sign_in: false
    servers:
      main:
        label: 'LDAP'
        ...

Basic Configuration Settings

Examples of user filters

Some examples of the user_filter field syntax:

• '(employeeType=developer)'
• '(&(objectclass=user)(|(samaccountname=momo)(samaccountname=toto)))'

SSL Configuration Settings

Attribute Configuration Settings

LDAP attributes that GitLab uses to create an account for the LDAP user. The specified attribute can either be the attribute name as a string (for example, 'mail'), or an array of attribute names to try in order (for example, ['mail', 'email']). Note that the user’s LDAP sign-in is the attribute specified as uid above.

LDAP Sync Configuration Settings

Set up LDAP user filter

If you want to limit all GitLab access to a subset of the LDAP users on your LDAP server, the first step should be to narrow the configured base. However, it’s sometimes necessary to further filter users. In this case, you can set up an LDAP user filter. The filter must comply with RFC 4515.

Omnibus configuration

gitlab_rails['ldap_servers'] = {
'main' => {
  # snip...
  'user_filter' => '(employeeType=developer)'
  }
}

Source configuration

production:
  ldap:
    servers:
      main:
        # snip...
        user_filter: '(employeeType=developer)'

If you want to limit access to the nested members of an Active Directory group, use the following syntax:

(memberOf:1.2.840.113556.1.4.1941:=CN=My Group,DC=Example,DC=com)

For more information about this “LDAP_MATCHING_RULE_IN_CHAIN” filter, see the following Microsoft Search Filter Syntax document. Support for nested members in the user filter shouldn’t be confused with group sync nested groups support.

GitLab does not support the custom filter syntax used by OmniAuth LDAP.

Escaping special characters

The user_filter DN can contain special characters. For example:

• A comma:

  OU=GitLab, Inc,DC=gitlab,DC=com
  

• Open and close brackets:

  OU=Gitlab (Inc),DC=gitlab,DC=com
  

  These characters must be escaped as documented in RFC 4515.

• Escape commas with \2C. For example:

  OU=GitLab\2C Inc,DC=gitlab,DC=com
  

• Escape open and close brackets with \28 and \29, respectively. For example:

  OU=Gitlab \28Inc\29,DC=gitlab,DC=com
  

Enabling LDAP username lowercase

Some LDAP servers, depending on their configurations, can return uppercase usernames. This can lead to several confusing issues such as creating links or namespaces with uppercase names.

GitLab can automatically lowercase usernames provided by the LDAP server by enabling the configuration option lowercase_usernames. By default, this configuration option is false.

Omnibus configuration

1. Edit /etc/gitlab/gitlab.rb:

   gitlab_rails['ldap_servers'] = {
   'main' => {
     # snip...
     'lowercase_usernames' => true
     }
   }
   

2. Reconfigure GitLab for the changes to take effect.

Source configuration

1. Edit config/gitlab.yaml:

   production:
     ldap:
       servers:
         main:
           # snip...
           lowercase_usernames: true
   

2. Restart GitLab for the changes to take effect.

Disable LDAP web sign in

It can be useful to prevent using LDAP credentials through the web UI when an alternative such as SAML is preferred. This allows LDAP to be used for group sync, while also allowing your SAML identity provider to handle additional checks like custom 2FA.

When LDAP web sign in is disabled, users don’t see an LDAP tab on the sign-in page. This does not disable using LDAP credentials for Git access.

Omnibus configuration

1. Edit /etc/gitlab/gitlab.rb:

   gitlab_rails['prevent_ldap_sign_in'] = true
   

2. Reconfigure GitLab for the changes to take effect.

Source configuration

1. Edit config/gitlab.yaml:

   production:
     ldap:
       prevent_ldap_sign_in: true
   

2. Restart GitLab for the changes to take effect.

Using encrypted credentials

Instead of having the LDAP integration credentials stored in plaintext in the configuration files, you can optionally use an encrypted file for the LDAP credentials. To use this feature, you first need to enable GitLab encrypted configuration.

The encrypted configuration for LDAP exists in an encrypted YAML file. By default the file is created at shared/encrypted_configuration/ldap.yaml.enc. This location is configurable in the GitLab configuration.

The unencrypted contents of the file should be a subset of the secret settings from your servers block in the LDAP configuration.

The supported configuration items for the encrypted file are:

• bind_dn
• password

The encrypted contents can be configured with the LDAP secret edit Rake command.

Omnibus configuration

If initially your LDAP configuration looked like:

1. In /etc/gitlab/gitlab.rb:

    gitlab_rails['ldap_servers'] = {
    'main' => {
      # snip...
      'bind_dn' => 'admin',
      'password' => '123'
      }
    }

1. Edit the encrypted secret:

   sudo gitlab-rake gitlab:ldap:secret:edit EDITOR=vim
   

2. The unencrypted contents of the LDAP secret should be entered like:

   main:
     bind_dn: admin
     password: '123'
   

3. Edit /etc/gitlab/gitlab.rb and remove the settings for user_bn and password.

4. Reconfigure GitLab for the changes to take effect.

Source configuration

If initially your LDAP configuration looked like:

1. In config/gitlab.yaml:

   production:
     ldap:
       servers:
         main:
           # snip...
           bind_dn: admin
           password: '123'
   

2. Edit the encrypted secret:

   bundle exec rake gitlab:ldap:secret:edit EDITOR=vim RAILS_ENVIRONMENT=production
   

3. The unencrypted contents of the LDAP secret should be entered like:

   main:
    bind_dn: admin
    password: '123'
   

4. Edit config/gitlab.yaml and remove the settings for user_bn and password.

5. Restart GitLab for the changes to take effect.

Encryption

TLS Server Authentication

There are two encryption methods, simple_tls and start_tls.

For either encryption method, if setting verify_certificates: false, TLS encryption is established with the LDAP server before any LDAP-protocol data is exchanged but no validation of the LDAP server’s SSL certificate is performed.

Limitations

TLS Client Authentication

Not implemented by Net::LDAP.

You should disable anonymous LDAP authentication and enable simple or SASL authentication. The TLS client authentication setting in your LDAP server cannot be mandatory and clients cannot be authenticated with the TLS protocol.

Multiple LDAP servers

With GitLab, you can configure multiple LDAP servers that your GitLab instance connects to.

To add another LDAP server:

1. Duplicate the settings under the main configuration.
2. Edit them to match the additional LDAP server.

Be sure to choose a different provider ID made of letters a-z and numbers 0-9. This ID is stored in the database so that GitLab can remember which LDAP server a user belongs to.

Based on the example illustrated on the image above, our gitlab.rb configuration would look like:

gitlab_rails['ldap_enabled'] = true
gitlab_rails['ldap_servers'] = {
'main' => {
  'label' => 'GitLab AD',
  'host' =>  'ad.example.org',
  'port' => 636,
  ...
  },

'secondary' => {
  'label' => 'GitLab Secondary AD',
  'host' =>  'ad-secondary.example.net',
  'port' => 636,
  ...
  },

'tertiary' => {
  'label' => 'GitLab Tertiary AD',
  'host' =>  'ad-tertiary.example.net',
  'port' => 636,
  ...
  }

}

If you configure multiple LDAP servers, use a unique naming convention for the label section of each entry. That label is used as the display name of the tab shown on the sign-in page.

User sync

Once per day, GitLab runs a worker to check and update GitLab users against LDAP.

The process executes the following access checks:

• Ensure the user is still present in LDAP.
• If the LDAP server is Active Directory, ensure the user is active (not blocked/disabled state). This is checked only if active_directory: true is set in the LDAP configuration.

In Active Directory, a user is marked as disabled/blocked if the user account control attribute (userAccountControl:1.2.840.113556.1.4.803) has bit 2 set.

For more information, see Bitmask Searches in LDAP.

The user is set to an ldap_blocked state in GitLab if the previous conditions fail. This means the user cannot sign in or push or pull code.

The process also updates the following user information:

• Email address
• SSH public keys (if sync_ssh_keys is set)
• Kerberos identity (if Kerberos is enabled)

The LDAP sync process:

• Updates existing users.
• Creates new users on first sign in.

Adjusting LDAP user sync schedule

By default, GitLab runs a worker once per day at 01:30 a.m. server time to check and update GitLab users against LDAP.

You can manually configure LDAP user sync times by setting the following configuration values, in cron format. If needed, you can use a crontab generator. The example below shows how to set LDAP user sync to run once every 12 hours at the top of the hour.

Omnibus installations

1. Edit /etc/gitlab/gitlab.rb:

   gitlab_rails['ldap_sync_worker_cron'] = "0 */12 * * *"
   

2. Reconfigure GitLab for the changes to take effect.

Source installations

1. Edit config/gitlab.yaml:

   cron_jobs:
     ldap_sync_worker_cron:
       "0 */12 * * *"
   

2. Restart GitLab for the changes to take effect.

Group Sync

If your LDAP supports the memberof property, when the user signs in for the first time GitLab triggers a sync for groups the user should be a member of. That way they don’t need to wait for the hourly sync to be granted access to their groups and projects.

A group sync process runs every hour on the hour, and group_base must be set in LDAP configuration for LDAP synchronizations based on group CN to work. This allows GitLab group membership to be automatically updated based on LDAP group members.

The group_base configuration should be a base LDAP ‘container’, such as an ‘organization’ or ‘organizational unit’, that contains LDAP groups that should be available to GitLab. For example, group_base could be ou=groups,dc=example,dc=com. In the configuration file it looks like the following.

Omnibus configuration

1. Edit /etc/gitlab/gitlab.rb:

   gitlab_rails['ldap_servers'] = {
   'main' => {
     # snip...
     'group_base' => 'ou=groups,dc=example,dc=com',
     }
   }
   

2. Apply your changes to GitLab.

Source configuration

1. Edit /home/git/gitlab/config/gitlab.yml:

   production:
     ldap:
       servers:
         main:
           # snip...
           group_base: ou=groups,dc=example,dc=com
   

2. Restart GitLab for the changes to take effect.

To take advantage of group sync, group owners or maintainers need to create one or more LDAP group links.

Adding group links

For information on adding group links by using CNs and filters, refer to the GitLab groups documentation.

Administrator sync

As an extension of group sync, you can automatically manage your global GitLab administrators. Specify a group CN for admin_group and all members of the LDAP group are given administrator privileges. The configuration looks like the following.

Omnibus configuration

1. Edit /etc/gitlab/gitlab.rb:

   gitlab_rails['ldap_servers'] = {
   'main' => {
     # snip...
     'group_base' => 'ou=groups,dc=example,dc=com',
     'admin_group' => 'my_admin_group',
     }
   }
   

2. Apply your changes to GitLab.

Source configuration

1. Edit /home/git/gitlab/config/gitlab.yml:

   production:
     ldap:
       servers:
         main:
           # snip...
           group_base: ou=groups,dc=example,dc=com
           admin_group: my_admin_group
   

2. Restart GitLab for the changes to take effect.

Global group memberships lock

“Lock memberships to LDAP synchronization” setting allows instance administrators to lock down user abilities to invite new members to a group.

When enabled, the following applies:

• Only administrator can manage memberships of any group including access levels.
• Users are not allowed to share project with other groups or invite members to a project created in a group.

To enable it you need to:

1. Enable LDAP
2. On the top bar, select Menu > Admin.
3. On the left sidebar, select Settings > General.
4. Expand the Visibility and access controls section.
5. Ensure the Lock memberships to LDAP synchronization checkbox is selected.

Adjusting LDAP group sync schedule

By default, GitLab runs a group sync process every hour, on the hour. The values shown are in cron format. If needed, you can use a Crontab Generator.

You can manually configure LDAP group sync times by setting the following configuration values. The example below shows how to set group sync to run once every two hours at the top of the hour.

Omnibus installations

1. Edit /etc/gitlab/gitlab.rb:

   gitlab_rails['ldap_group_sync_worker_cron'] = "0 */2 * * * *"
   

2. Reconfigure GitLab for the changes to take effect.

Source installations

1. Edit config/gitlab.yaml:

   cron_jobs:
     ldap_group_sync_worker_cron:
         "*/30 * * * *"
   

2. Restart GitLab for the changes to take effect.

External groups

Using the external_groups setting allows you to mark all users belonging to these groups as external users. Group membership is checked periodically through the LdapGroupSync background task.

Omnibus configuration

1. Edit /etc/gitlab/gitlab.rb:

   gitlab_rails['ldap_servers'] = {
   'main' => {
     # snip...
     'external_groups' => ['interns', 'contractors'],
     }
   }
   

2. Apply your changes to GitLab.

Source configuration

1. Edit config/gitlab.yaml:

   production:
     ldap:
       servers:
         main:
           # snip...
           external_groups: ['interns', 'contractors']
   

2. Restart GitLab for the changes to take effect.

Group sync technical details

This section outlines what LDAP queries are executed and what behavior you can expect from group sync.

Group member access are downgraded from a higher level if their LDAP group membership changes. For example, if a user the Owner role in a group and the next group sync reveals they should only have the Developer role, their access is adjusted accordingly. The only exception is if the user is the last owner in a group. Groups need at least one owner to fulfill administrative duties.

Supported LDAP group types/attributes

GitLab supports LDAP groups that use member attributes:

• member
• submember
• uniquemember
• memberof
• memberuid

This means group sync supports (at least) LDAP groups with the following object classes:

• groupOfNames
• posixGroup
• groupOfUniqueNames

Other object classes should work if members are defined as one of the mentioned attributes.

Active Directory supports nested groups. Group sync recursively resolves membership if active_directory: true is set in the configuration file.

Nested group memberships

Nested group memberships are resolved only if the nested group is found in the configured group_base. For example, if GitLab sees a nested group with DN cn=nested_group,ou=special_groups,dc=example,dc=com but the configured group_base is ou=groups,dc=example,dc=com, cn=nested_group is ignored.

Queries

• Each LDAP group is queried a maximum of one time with base group_base and filter (cn=<cn_from_group_link>).
• If the LDAP group has the memberuid attribute, GitLab executes another LDAP query per member to obtain each user’s full DN. These queries are executed with base base, scope ‘base object’, and a filter depending on whether user_filter is set. Filter may be (uid=<uid_from_group>) or a joining of user_filter.

Benchmarks

Group sync was written to be as performant as possible. Data is cached, database queries are optimized, and LDAP queries are minimized. The last benchmark run revealed the following metrics:

For 20,000 LDAP users, 11,000 LDAP groups, and 1,000 GitLab groups with 10 LDAP group links each:

• Initial sync (no existing members assigned in GitLab) took 1.8 hours
• Subsequent syncs (checking membership, no writes) took 15 minutes

These metrics are meant to provide a baseline and performance may vary based on any number of factors. This was an extreme benchmark and most instances don’t have near this many users or groups. Disk speed, database performance, network and LDAP server response time affects these metrics.

Troubleshooting

See our administrator guide to troubleshooting LDAP.