Configure SAML with Microsoft Entra ID

Note

This documentation covers configuring Entra ID for SAML authentication. If you need to configure Entra ID for OpenID Connect authentication instead, see the Entra ID Single Sign-On documentation.

The following process provides steps to configure SAML with Microsoft Entra ID for Mattermost.

See the encryption options documentation for details on what encryption methods Mattermost supports for SAML.

Before you begin

Before you begin, you need to generate encryption certificates for encrypting the SAML connection.

  1. You can use the Bash script from the mattermost/docs repository on GitHub, or any other suitable method. See the generate self-signed certificates documentation for details on generating a self-signed x509v3 certificate for use with multiple URLs / IPs.

  2. Save the two files that are generated. They are the private key and the public key. In the System Console, they are referred to as the Service Provider Private Key and the Service Provider Public Certificate respectively.

Prerequisites

  • A Microsoft Entra tenant containing applicable user data.

  • A verified custom domain for your tenant. See Microsoft’s Add your custom domain name to your tenant documentation for details.

  • A Microsoft Entra ID P1 or P2 license.

Set up an enterprise app for Mattermost SSO in Entra ID

  1. Log into the Microsoft Azure portal and select the Microsoft Entra ID service.

  2. In the left menu, select Manage > Enterprise applications.

  3. Select the New application button.

  4. In the Search application field, search for Microsoft Entra SAML Toolkit and select Microsoft Entra SAML Toolkit.

  5. In the Name field, enter Mattermost SAML then select the Create button.

  6. In the Mattermost SAML enterprise application settings, select Manage > Users and Groups to assign users and/or groups to the application or select Manage > Properties then set Assignment required? to No then select Save.

  7. In the Mattermost SAML enterprise application settings, select Manage > Single sign-on then select SAML under Select a single sign-on method.

  8. Select Edit in the Basic SAML Configuration section then set the below fields then select Save:

  • Identity (Entity ID): https://<your-mattermost-url>

  • Reply URL (Assertion Consumer Service URL): https://<your-mattermost-url>/login/sso/saml

  • Sign on URL: https://<your-mattermost-url>/login

  1. Select Edit in the Attributes & Claims section then set the below attributes:

  1. Set the the Unique User Identifier (Name ID) required claim Name identifier format and Source attribute values as required for your environment. Setting the Source attribute to an immutable value such as user.objectid is recommended.

  2. Edit claim names and namespaces under Additional claims to match SAML attribute settings you wish to set in Mattermost. Configurable settings are Email, Username, Id, Guest, Admin, First Name, Last Name, Nickname, Position, and Preferred Language.

  1. Select Edit in the SAML Certificates section. Select Sign SAML response and assertion for Signing Option and SHA-256 for Signing Algorithm then select Save.

  2. Select the Certificate (Base64) Download link in the SAML Certificates section. This is the Identity Provider Public Certificate to be uploaded to Mattermost.

  3. In the Mattermost SAML enterprise application settings, select Security > Token encryption. Select Import Certificate to import the Service Provider certificate. If you used the Bash script referenced in the Before you begin section, this is the mattermost-x509.crt file. The Import dialog says to upload a certificate with a file extension .cer, but .crt files are also accepted. Upload the file then select Add.

  4. Select the ... to the right of the imported certificate details, select Activate token encryption certificate, then select Yes to activate.

  5. On the Home page for Microsoft Entra ID, select the Overview link in the left navigation menu and copy the Tenant ID value. The Tenant ID will be used in Mattermost SAML 2.0 URL settings.

  6. In the left navigation menu, select Manage > Enterprise applications. Select the Mattermost SAML application then copy the Application ID. The Application ID will be used in the Identity Provider Metadata URL setting in the Mattermost SAML 2.0 settings.

Configure SAML Sign-On for Mattermost

  1. In the Mattermost System Console, select Authentication > SAML 2.0.

  2. Set Enable Login With SAML 2.0 to True.

  3. Set Identity Provider Metadata URL: https://login.microsoftonline.com/<your-tenant-id>/federationmetadata/2007-06/federationmetadata.xml?appid=<your-app-id>

  4. Select Get SAML Metadata From IdP to verify that the SAML metadata can be retrieved successfully.

  5. Set SAML SSO URL: https://login.microsoftonline.com/<your-tenant-id>/saml2

  6. Set Identity Provider Issuer URL (trailing slash is required): https://sts.windows.net/<your-tenant-id>/

  7. Choose the Identity Provider Public Certificate file from step 11 of Set up an enterprise app for Mattermost SSO in Entra ID then upload.

  8. Set Verify Signature to True.

  9. Set Service Provider Login URL: https://<your-mattermost-url>/login/sso/saml

  10. Set Service Provider Identifier: https://<your-mattermost-url>

  11. Set Enable Encryption to True

  12. Choose your Service Provider Private Key file then upload. If you used the Bash script referenced in the Before you begin section, this is the mattermost-x509.key file.

  13. Choose your Service Provider Public Certificate then upload. If you used the Bash script referenced in the Before you begin section, this is the mattermost-x509.crt file.

  14. Set Sign Request to suit your environment. The Signature Algorithm must match the algorithm set in Entra ID (RSAwithSHA256 is recommended).

Note

The Test single sign-on with Mattermost SAML tool in Microsoft Entra ID does not sign the request even if Sign Request is set to True in Mattermost. Depending on your security settings and key length, the Entra ID testing tool may successfully sign in while an actual sign in request from your Mattermost login page results in the error AADSTS90015: Requested query string is too long. since Entra ID handles the initial request with an HTTP GET redirect rather than HTTP POST.

  1. Set attribute settings to match attributes configured in step 9 of the Set up an enterprise app for Mattermost SSO in Entra ID section.

  2. Set the Login Button Text to suit your environment.

  3. Select the Save button.

Configure SAML synchronization with AD/LDAP

In addition to configuring SAML sign-in, you can optionally configure synchronizing SAML accounts with AD/LDAP. When configured:

  • Mattermost queries AD/LDAP for relevant account information and updates SAML accounts based on changes to attributes (first name, last name, and nickname)

  • Accounts disabled in AD/LDAP are deactivated in Mattermost, and their active sessions are revoked once Mattermost synchronizes attributes.

To configure SAML synchronization with AD/LDAP:

  1. Go to System Console > Authentication > SAML 2.0, then set Enable Synchronizing SAML Accounts With AD/LDAP to true.

  2. Go to System Console > Authentication > AD/LDAP to open the AD/LDAP wizard, navigate to the Connection Settings section, then set Enable Synchronization with AD/LDAP to true.

  3. To ignore guest users when sychronizing, go to System Console > Authentication > SAML 2.0, then set Ignore Guest Users when Synchronizing with AD/LDAP to true.

  4. Set the rest of the AD/LDAP settings based on configuration settings documentation to connect Mattermost with your AD/LDAP server.

    If you don’t want to enable AD/LDAP sign-in, go to System Console > Authentication > AD/LDAP wizard, navigate to the Connection Settings section, then set Enable sign-in with AD/LDAP to false.

  5. To specify how often Mattermost synchronizes SAML user accounts with AD/LDAP, go to System Console > Authentication > AD/LDAP wizard, navigate to the Sync Performance section, then set a Synchronization Interval in minutes. The default setting is 60 minutes. If you want to synchronize immediately after disabling an account, go to the Sync History section and select AD/LDAP Synchronize Now.

  6. To confirm that Mattermost can successfully connect to your AD/LDAP server, go to System Console > Authentication > AD/LDAP wizard, navigate to the Connection Settings section, then select Test Connection.

Once the synchronization with AD/LDAP is enabled, user attributes are synchronized with AD/LDAP based on their email address. If a user with a given email address doesn’t have an AD/LDAP account, they will be deactivated in Mattermost on the next AD/LDAP sync.

To re-activate the account:

  1. Add the user to your AD/LDAP server.

  2. Purge all caches in Mattermost by going to System Console > Environment > Web Server, then select Purge All Caches.

  3. Run AD/LDAP synchronization by going to System Console > Authentication > AD/LDAP wizard, navigating to the Sync History section, then select AD/LDAP Synchronize Now.

  4. Purge all caches again in Mattermost by going to System Console > Environment > Web Server, then select Purge All Caches again. This re-activates the account in Mattermost.

Note

  • If a user is deactivated from AD/LDAP, they will be deactivated in Mattermost on the next sync. They will be shown as “Deactivated” in the System Console users list, all of their sessions will expire and they won’t be able to log back in to Mattermost.

  • If a user is deactivated from SAML, their session won’t expire until they’re deactivated from AD/LDAP. However, they won’t be able to log back in to Mattermost.

  • SAML synchronization with AD/LDAP is designed to pull user attributes such as first name and last name from your AD/LDAP, not to control authentication. In particular, the user filter cannot be used to control who can log in to Mattermost, this should be controlled by your SAML service provider’s group permissions.

See technical description of SAML synchronization with AD/LDAP for more details.

Override SAML data with AD/LDAP data

Alternatively, you can choose to override SAML bind data with AD/LDAP information. For more information on binding a user with the SAML ID Attribute, please refer to this documentation.

This process overrides SAML email address with AD/LDAP email address data or SAML Id Attribute with AD/LDAP Id Attribute if configured. We recommend using this configuration with the SAML ID Attribute to help ensure new users are not created when the email address changes for a user.

To ensure existing user accounts do not get disabled in this process, ensure the SAML IDs match the LDAP IDs by exporting data from both systems and comparing the ID data. Mapping ID Attributes for both AD/LDAP and SAML within Mattermost to fields that hold the same data will ensure the IDs match as well.

  1. Set the SAML Id Attribute by going to System Console > Authentication > SAML 2.0 > Id Attribute.

  2. Set System Console > Authentication > SAML 2.0 > Override SAML bind data with AD/LDAP information to true.

  3. Set System Console > Authentication > SAML 2.0 > Enable Synchronizing SAML Accounts With AD/LDAP to true.

  4. Run AD/LDAP sync by going to System Console > Authentication > AD/LDAP wizard, navigating to the Sync History section, then select AD/LDAP Synchronize Now.

Frequently Asked Questions

What encryption options are supported for SAML?

See the encryption options documentation for details on what encryption methods Mattermost supports for SAML.

How to bind authentication to Id attribute instead of email

Alternatively, you can use an Id attribute instead of email to bind the user. We recommend choosing an ID that is unique and will not change over time.

Configuring with an Id attribute allows you to reuse an email address for a new user without the old user’s information being exposed. For instance, if a user with an email address joe.smith@mattermost.com was once an employee, a new employee named Joe Smith can use the same email. This configuration is also useful when a user’s name changes and their email needs to be updated.

This process was designed with backwards compatibility to email binding. Here is the process applied to new account creations and to accounts logging in after the configuration:

  • A user authenticated with SAML is bound to the SAML service user using the Id Attribute (as long as it has been configured) or bound by email using the email received from SAML.

  • When the user tries to login and the SAML server responds with a valid authentication, then the server uses the “Id” field of the SAML authentication to search the user.

  • If a user bound to that ID already exists, it logs in as that user.

  • If a user bound to that ID does not exist, it will search base on the email.

  • If a user bound to the email exists, it logs in with email and updates the autentication data to the ID, instead of the email.

  • If a user bound to the ID or email does not exist, it will create a new Mattermost account bound to the SAML account by ID and will allow the user to log in.

Note

Existing accounts won’t update until they log in to the server.

Can SAML via Microsoft ADFS be configured with Integrated Windows Authentication (IWA)?

Yes. IWA is supported on the browser, with support added to iOS and Android mobile apps in Q2/2019 (mobile apps v1.18 and later).

However, IWA is not supported on the Mattermost Desktop Apps due to a limitation in Electron. As a workaround you may create a browser desktop shortcut for quick access to Mattermost, just like a Desktop App.

Can I provision and deprovision users who log in via SAML?

Yes, but this relies on AD/LDAP to do so. Currently, we do not support SCIM. See “How do I deactivate users?” for more information.

How do I migrate users from one authentication method (e.g. email) to SAML?

See the mmctl user migrate-auth command documentation for details.

How is SAML different from OAuth 2.0 and OpenId Connect?

OAuth 2.0 was primarily intended for delegated authorization, where an app is authorized to access resources, such as Google contact list. It doesn’t deal with authentication.

OpenID Connect is built on top of OAuth 2.0, which supports authentication and thus direct SSO.

SAML is like OpenID Connect, except typically used in enterprise settings. OpenID Connect is more common in consumer websites and web/mobile apps.

Learn more at https://hackernoon.com/demystifying-oauth-2-0-and-openid-connect-and-saml-12aa4cf9fdba.