Configure SAML with Keycloak
The following process provides steps to configure SAML with Keycloak for Mattermost.
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This was tested with Keycloak v18.0.0.
Additionally, you don’t typically need to make a realm dedicated to Mattermost. We recommend adding Mattermost as a client to your primary realm.
Log in to Keycloak as an administrator.
Select Clients, then Create and Save. You’ll use this client ID in a later step.
Edit the Mattermost client to have the below values:
Encrypt Assertions: ON
Force Name ID Format: ON
Name ID Format: Email
Save the client config.
Navigate to Keys within the client config.
Select Generate new keys.
Select Export, use the values below, and then select Download. Once you’ve downloaded it, navigate back to the Mattermost client in Keycloak for the next steps.
In the image below, we used Mattermost for the Realm Certificate Alias. You can use any value that you would like here, as it’s designed to identify what this certificate is within your Keycloak realm.
Add the default attributes:
Within your Mattermost client select Mappers.
Select Add Buildin
Select the X500 email, X500 givenName, and X500 surname attributes.
Select Add selected.
Add the username and ID attribute.
If you’re planning to sync your SAML users with LDAP within Mattermost, the ID value used here must match with your Mattermost LDAP
With the Mappers section of your client, select Create.
Set Name to
Under Mapper Type select User Property.
Set Property to
username(This is case sensitive and must be lowercase).
Set SAML Attribute Name to
Repeat this step and use the property of
idto create the ID Attribute.
- Once done your Mappers should look like this:
Get the metadata URL from Keycloak:
Within your Realm, select Realm Settings.
At the bottom of the General tab you should see a SAML 2.0 Identity Provider Metadata endpoint. Right-click and copy this URL. Store for the next step.
Start the Mattermost server and log in to Mattermost as a System Administrator. Go to System Console > Authentication > SAML.
Set the Identity Provider Metadata URL to the value you copied from the step above and select Get SAML Metadata from IdP. The metadata import will populate fields related to your Keycloak configuration.
If you have any issues with this import, you can check the
mattermost.logfile for more information. You will need to turn on debug logging and try again if you do not already have debug logging enabled.
Set the below fields:
Verify Signature: false
Service Provider Login URL:
Service Provider Identifier:
The Service Provider Identifier will match the Client ID that you configured in the second Keycloak step.
Configure the Encryption using the key you downloaded in step 8 of the Keycloak config.
.crtfile from the
openssl pkcs12 -in keystore.p12 -out mattermost.crt -nodes
.keyfile from the
openssl pkcs12 -in keystore.p12 -out mattermost.key -nodes -nocerts
Upload both of these files within the Mattermost System Console. Make sure to select Upload.
Service Provider Private Key:
Service Provider Private Certificate:
(Optional) Set up request signing with the below parameters.
Set attributes for the SAML Assertions, which will update user information in Mattermost.
The attributes below are from steps 8 and 9 above. These values must be the SAML Attribute Name within Keycloak. See documentation on SAML configuration settings for more details.
You’re done! If you’d like to confirm SAML SSO is successfully enabled, switch your System Administrator account from email to SAML-based authentication via Profile > Security > Sign-in Method > Switch to SAML SSO and log in with your SAML credentials to complete the switch.
It’s also recommended to post an announcement about how the migration will work for users.
You may also configure SAML for Keycloak by editing
config.json. Before starting the Mattermost server, edit
config.json to enable SAML based on SAML configuration settings. You must restart the Mattermost server for the changes to take effect.
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 made inactive in Mattermost, and their active sessions are revoked once Mattermost synchronizes attributes.
To configure SAML synchronization with AD/LDAP:
Go to System Console > Authentication > SAML 2.0, then set Enable Synchronizing SAML Accounts With AD/LDAP to true.
Go to System Console > Authentication > AD/LDAP, then set Enable Synchronization with AD/LDAP to true.
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.
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, then set Enable sign-in with AD/LDAP to false.
To specify how often Mattermost synchronizes SAML user accounts with AD/LDAP, go to System Console > Authentication > AD/LDAP, then set a Synchronization Interval in minutes. The default setting is 60 minutes. If you want to synchronize immediately after disabling an account, select AD/LDAP Synchronize Now.
To confirm that Mattermost can successfully connect to your AD/LDAP server, go to System Console > Authentication > AD/LDAP, then select AD/LDAP Test.
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:
Add the user to your AD/LDAP server.
Purge all caches in Mattermost by going to System Console > Environment > Web Server, then select Purge All Caches.
Run AD/LDAP synchronization by going to System Console > Authentication > AD/LDAP, then select AD/LDAP Synchronize Now.
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.
If a user is deactivated from AD/LDAP, they will be deactivated in Mattermost on the next sync. They will be shown as “Inactive” 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.
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.
Set the SAML
Id Attributeby going to System Console > Authentication > SAML 2.0 > Id Attribute.
Set System Console > Authentication > SAML 2.0 > Override SAML bind data with AD/LDAP information to true.
Set System Console > Authentication > SAML 2.0 > Enable Synchronizing SAML Accounts With AD/LDAP to true.
Run AD/LDAP sync by going to System Console > Authentication > AD/LDAP, then select AD/LDAP Synchronize Now.
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 email@example.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.
Existing accounts won’t update until they log in to the server.
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.
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.
See the mmctl user migrate-auth command documentation for details.
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.