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[ Basic integration ] [ Advanced integration ] [ Next Steps ]


This guide describes how Gitlab CE can be configured as a SAML Service Provider for eduTEAMS and it assumes:

  • You are using Gitlab v13.x
  • You have access to edit the Gitlab configuration file at  /etc/gitlab/gitlab.rb
  • The URL of your Gitlab instance is https://gitlab.example.com
  • The name of your VO is Test_VO

It is possible to connect a Gitlab instance with eduTEAMS either as a SAML Service Provider or an OIDC client. The integration via SAML provides more benefits as the SAML implementation in Gitlab has (limited) support for authorizing users using groups. The OIDC implementation in Gitlab supports only authenticating users. As a reference this guide is available: https://docs.gitlab.com/13.0/ee/integration/saml.html .

In order to configure your Gitlab for eduTEAMS, you need the following information:

Configuration Option

Value

Description

issuer

https://gitlab.example.com

A unique name identifying the gitlab application to the proxy
idp_sso_target_url

https://proxy.acc.eduteams.org/saml2sp/sso/redirect

This is the eduTEAMS endpoint supporting the HTTP-Redirect SAML 2.0 Binding
idp_cert_fingerprint72:8A:6C:6B:63:35:3F:E0:BF:70:8D:41:0E:B7:02:CF:C5:86:53:24This is the fingerprint of the signing certificate used by the eduTEAMS SAML frontend
name_identifier_formaturn:oasis:names:tc:SAML:2.0:nameid-format:persistentThe NameID format requested
uidurn:oasis:names:tc:SAML:attribute:subject-idSee Attributes available to Relying Parties#eduTEAMSIdentifier
emailurn:oid:0.9.2342.19200300.100.1.3See Attributes available to Relying Parties#Emailaddress
first_nameurn:oid:2.5.4.42See Attributes available to Relying Parties#GivenName
last_nameurn:oid:2.5.4.4See Attributes available to Relying Parties#FamilyName
groups_attributeurn:oid:1.3.6.1.4.1.5923.1.1.1.7See Attributes available to Relying Parties#Groups

Basic integration

In the basic integration, all users from your VO will be able to authenticate via eduTEAMS and access the Gitlab service.

Below is an example configuration:
/etc/gitlab/gitlab.rb

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# SECTION 3
gitlab_rails['omniauth_enabled'] = true
gitlab_rails['omniauth_allow_single_sign_on'] = ['saml']
gitlab_rails['omniauth_block_auto_created_users'] = false
 
# SECTION 4
gitlab_rails['omniauth_auto_link_saml_user'] = true
 
# SECTION 6
gitlab_rails['omniauth_providers'] = [
   {
      name: 'saml',
      label: 'eduTEAMS',
      args: {
         assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
         idp_cert_fingerprint: '72:8A:6C:6B:63:35:3F:E0:BF:70:8D:41:0E:B7:02:CF:C5:86:53:24',
         idp_sso_target_url: 'https://proxy.eduteams.org/saml2sp/sso/redirect',
         issuer: 'https://gitlab.example.com',
         name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent',
         uid: ["urn:oasis:names:tc:SAML:attribute:subject-id"],
         email: ["urn:oid:0.9.2342.19200300.100.1.3",],
         first_name: ["urn:oid:2.5.4.42"],
         last_name: ["urn:oid:2.5.4.4"]
      },
      groups_attribute: 'urn:oid:1.3.6.1.4.1.5923.1.1.1.7',
      required_groups: [],
      admin_groups: [],
      audit_groups: []
   }
]

Advanced integration

The SAML login in Gitlab includes support for limiting access to specific groups from your VO. You can control which groups can access the Gitlab instance using the required_groups configuration option. When required_groups is not set or it is empty, anyone with proper authentication will be able to use the service.

It is also possible to automatically identify whether a user should be considered an external user based on the user’s group membership in your VO in eduTEAMS This feature does not allow you to automatically add users to GitLab Groups, it simply allows you to mark users as External if they are members of certain groups of users. You can control the users of which groups will be marked as External using the the external_groups configuration option.

This setting works very similarly to the External Groups setting. The requirements are the same, your IdP needs to pass Group information to GitLab, you need to tell GitLab where to look for the groups in the SAML response, and which group should be considered admin groups

This setting also follows the requirements documented for the External Groups setting. GitLab uses the Group information provided by your IdP to determine if a user should be assigned the auditor role.

Below is an example configuration:
/etc/gitlab/gitlab.rb

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# SECTION 3
gitlab_rails['omniauth_enabled'] = true
gitlab_rails['omniauth_allow_single_sign_on'] = ['saml']
gitlab_rails['omniauth_block_auto_created_users'] = false
 
# SECTION 4
gitlab_rails['omniauth_auto_link_saml_user'] = true
 
# SECTION 6
gitlab_rails['omniauth_providers'] = [
   {
      name: 'saml',
      label: 'eduTEAMS',
      args: {
         assertion_consumer_service_url: 'https://gitlab.example.com/users/auth/saml/callback',
         idp_cert_fingerprint: '72:8A:6C:6B:63:35:3F:E0:BF:70:8D:41:0E:B7:02:CF:C5:86:53:24',
         idp_sso_target_url: 'https://proxy.eduteams.org/saml2sp/sso/redirect',
         issuer: 'https://example.gitlab.com',
         name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent',
         uid: ["urn:oasis:names:tc:SAML:attribute:subject-id"],
         email: ["urn:oid:0.9.2342.19200300.100.1.3",],
         first_name: ["urn:oid:2.5.4.42"],
         last_name: ["urn:oid:2.5.4.4"]
      },
      groups_attribute: 'urn:oid:1.3.6.1.4.1.5923.1.1.1.7',
      # Only the following groups in the Test_VO will be able to access this Gitlab instance:
      #
      # - Developers
      # - Admins:Gitlab
      # - Admins:Gitlab:Auditors
      required_groups: [
          'urn:geant:eduteams.org:service:eduteams:group:Test_VO:Developers#eduteams.org',
          'urn:geant:eduteams.org:service:eduteams:group:Test_VO:Developers#eduteams.org',
          'urn:geant:eduteams.org:service:eduteams:group:Test_VO:Admins:Gitlab#eduteams.org',
          'urn:geant:eduteams.org:service:eduteams:group:Test_VO:Admin:Gitlab:Auditors#eduteams.org',
      ],
      # Users from the following groups in the Test_VO will access this Gitlab instance as admins 
      #
      # - Admins:Gitlab:
      admin_groups: [
          'urn:geant:eduteams.org:service:eduteams:group:Test_VO:Admins:Gitlab#eduteams.org',
      ],
      # Users from the following groups in the Test_VO will access this Gitlab instance as auditors:
      #
      # - Admins:Gitlab:Auditors
      audit_groups: [
          'urn:geant:eduteams.org:service:eduteams:group:Test_VO:Admins:Gitlab:Auditors#eduteams.org',
      ],
      # Users from the following gorup in the Test_VO will access the Gitlab instance external users
      #
      # - Guests
      # - Contractors
      external_groups: [
          'urn:geant:eduteams.org:service:eduteams:group:Test_VO:Guests#eduteams.org',
          'urn:geant:eduteams.org:service:eduteams:group:Test_VO:Conractors#eduteams.org',
      }
   }
]

Next Steps

Check the SAML metadata URL of the Gitlab instance at https://gitlab.example.com/users/auth/saml/metadata (replace gitlab.example.com with the domain of your Gitlab instance). You should should something like the following:
Gitlab SAML Metadata

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<?xml version='1.0' encoding='UTF-8'?>
<md:EntityDescriptor ID="_9edb3dae-0919-40ff-b7c0-bffc63ba032b" entityID="https://gitlab.example.com" xmlns:md="urn:oasis:names:tc:SAML:2.0:metadata" xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">
    <md:SPSSODescriptor AuthnRequestsSigned="false" WantAssertionsSigned="false" protocolSupportEnumeration="urn:oasis:names:tc:SAML:2.0:protocol">
        <md:NameIDFormat>urn:oasis:names:tc:SAML:2.0:nameid-format:persistent</md:NameIDFormat>
        <md:AssertionConsumerService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" Location="https://gitlab.example.com/users/auth/saml/callback" index="0" isDefault="true" />
        <md:AttributeConsumingService index="1" isDefault="true">
            <md:ServiceName xml:lang="en">Required attributes</md:ServiceName>
            <md:RequestedAttribute FriendlyName="Email address" Name="email" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic" isRequired="false" />
            <md:RequestedAttribute FriendlyName="Full name" Name="name" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic" isRequired="false" />
            <md:RequestedAttribute FriendlyName="Given name" Name="first_name" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic" isRequired="false" />
            <md:RequestedAttribute FriendlyName="Family name" Name="last_name" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic" isRequired="false" />
        </md:AttributeConsumingService>
    </md:SPSSODescriptor>
</md:EntityDescriptor>

Congratulations, you have successfully configured your Gitlab instance for eduTEAMS. Now you can proceed registering your following the steps described in Registering services on the eduTEAMS Service

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