SAML on GitLab.com allows users to be automatically added to a group, and then allows those users to sign into GitLab.com. Users should already have an account on the GitLab instance, or can create one when logging in for the first time.
1. Configure your SAML server using the **Assertion consumer service URL** and **Identifier**. Alternatively GitLab provides [metadata XML configuration](#metadata-configuration). See [your identity provider's documentation](#providers) for more details.
GitLab.com uses the SAML NameID to identify users. The NameID element:
- Is a required field in the SAML response.
- Must be unique to each user.
- Must be a persistent value that will never change, such as a randomly generated unique user ID.
- Is case sensitive. The NameID must match exactly on subsequent login attempts, so should not rely on user input that could change between upper and lower case.
- Should not be an email address or username. We strongly recommend against these as it is hard to guarantee they will never change, for example when a person's name changes. Email addresses are also case-insensitive, which can result in users being unable to sign in.
CAUTION: **Warning:**
Once users have signed into GitLab using the SSO SAML setup, changing the `NameID` will break the configuration and potentially lock users out of the GitLab group.
#### NameID Format
We recommend setting the NameID format to `Persistent` unless using a field (such as email) that requires a different format.
With this option enabled, users must use your group's GitLab single sign on URL to be added to the group or be added via SCIM. Users cannot be added manually, and may only access project/group resources via the UI by signing in through the SSO URL.
However, users will not be prompted to log via SSO on each visit. GitLab will check whether a user has authenticated through the SSO link, and will only prompt the user to login via SSO if it has been longer than 7 days.
We intend to add a similar SSO requirement for [Git and API activity](https://gitlab.com/gitlab-org/gitlab/issues/9152) in the future.
#### Group-managed accounts
[Introduced in GitLab 12.1](https://gitlab.com/groups/gitlab-org/-/epics/709).
When SSO is being enforced, groups can enable an additional level of protection by enforcing the creation of dedicated user accounts to access the group.
Without group-managed accounts, users can link their SAML identity with any existing user on the instance. With group-managed accounts enabled, users are required to create a new, dedicated user linked to the group. The notification email address associated with the user is locked to the email address received from the configured identity provider.
When this option is enabled:
- All existing and new users in the group will be required to log in via the SSO URL associated with the group.
- On successfully authenticating, GitLab will prompt the user to create a new, dedicated account using the email address received from the configured identity provider.
Since use of the group-managed account requires the use of SSO, users of group-managed accounts will lose access to these accounts when they are no longer able to authenticate with the connected identity provider. In the case of an offboarded employee who has been removed from your identity provider:
| Azure | [Configuring single sign-on to applications](https://docs.microsoft.com/en-us/azure/active-directory/manage-apps/configure-single-sign-on-non-gallery-applications) |
| Ping Identity | [Add and configure a new SAML application](https://support.pingidentity.com/s/document-item?bundleId=pingone&topicId=xsh1564020480660-1.html) |
When [configuring your identify provider](#configuring-your-identity-provider), please consider the notes below for specific providers to help avoid common issues and as a guide for terminology used.
## Linking SAML to your existing GitLab.com account
To link SAML to your existing GitLab.com account:
1. Sign in to your GitLab.com account.
1. Locate the SSO URL for the group you are signing in to. A group Admin can find this on the group's **Settings > SAML SSO** page.
1. Visit the SSO URL and click **Authorize**.
1. Enter your credentials on the Identity Provider if prompted.
1. You will be redirected back to GitLab.com and should now have access to the group. In the future, you can use SAML to sign in to GitLab.com.
## Signing in to GitLab.com with SAML
1. Locate the SSO URL for the group you are signing in to. A group Admin can find this on a group's **Settings > SAML SSO** page. If configured, it might also be possible to sign in to GitLab starting from your Identity Provider.
1. Visit the SSO URL and click the **Sign in with Single Sign-On** button.
1. Enter your credentials on the Identity Provider if prompted.
1. You will be signed in to GitLab.com and redirected to the group.
Users can unlink SAML for a group from their profile page. This can be helpful if:
- You no longer want a group to be able to sign you in to GitLab.com.
- Your SAML NameID has changed and so GitLab can no longer find your user.
For example, to unlink the `MyOrg` account, the following **Disconnect** button will be available under **Profile > Accounts**:
## Glossary
| Term | Description |
|------|-------------|
| Identity Provider | The service which manages your user identities such as ADFS, Okta, Onelogin or Ping Identity. |
| Service Provider | SAML considers GitLab to be a service provider. |
| Assertion | A piece of information about a user's identity, such as their name or role. Also know as claims or attributes. |
| SSO | Single Sign On. |
| Assertion consumer service URL | The callback on GitLab where users will be redirected after successfully authenticating with the identity provider. |
| Issuer | How GitLab identifies itself to the identity provider. Also known as a "Relying party trust identifier". |
| Certificate fingerprint | Used to confirm that communications over SAML are secure by checking that the server is signing communications with the correct certificate. Also known as a certificate thumbprint. |
- The [NameID](#nameid), which we use to identify which user is signing in. If the user has previously signed in, this [must match the value we have stored](#verifying-nameid).
- The presence of a `X509Certificate`, which we require to verify the response signature.
- The `SubjectConfirmation` and `Conditions`, which can cause errors if misconfigured.
### Verifying NameID
In troubleshooting the Group SAML setup, any authenticated user can use the API to verify the NameID GitLab already has linked to the user by visiting [https://gitlab.com/api/v4/user](https://gitlab.com/api/v4/user) and checking the `extern_uid` under identities.
This can then be compared to the [NameID](#nameid) being sent by the Identity Provider by decoding the message with a [SAML debugging tool](#saml-debugging-tools). We require that these match in order to identify users.
### Message: "SAML authentication failed: Extern uid has already been taken"
This error suggests you are signed in as a GitLab user but have already linked your SAML identity to a different GitLab user. Sign out and then try to sign in again using the SSO SAML link, which should log you into GitLab with the linked user account.
If you do not wish to use that GitLab user with the SAML login, you can [unlink the GitLab account from the group's SAML](#unlinking-accounts).
### Message: "SAML authentication failed: User has already been taken"
The user you are signed in with already has SAML linked to a different identity. This might mean you've attempted to link multiple SAML identities to the same user for a given Identity Provider. This could also be a symptom of the Identity Provider returning an inconsistent [NameID](#nameid).
To change which identity you sign in with, you can [unlink the previous SAML identity](#unlinking-accounts) from this GitLab account.
### Message: "SAML authentication failed: Extern uid has already been taken, User has already been taken"
Getting both of these errors at the same time suggests the NameID capitalization provided by the Identity Provider didn't exactly match the previous value for that user.
This can be prevented by configuring the [NameID](#nameid) to return a consistent value. Fixing this for an individual user involves [unlinking SAML in the GitLab account](#unlinking-accounts), although this will cause group membership and Todos to be lost.
