If your preferred identity provider doesn’t have a connector with Slack, you can use a custom SAML connection.
Note: we're happy to help with your setup, but we can't always guarantee your connection will work with Slack. Read our Troubleshoot SAML authorisation errors article or send us a note and we'll do what we can!
Parameters
Follow these parameters to configure your custom SAML connection.
Provisioning
Slack supports Identity Provider (IDP) Initiated Flow, Service Provider (SP) Initiated flow, Just In Time provisioning and automatic provisioning through our SCIM API.
For SP-initiated single sign-on, go to https://yourdomain.slack.com.
SSO post-backup URL
https://yourdomain.slack.com/sso/saml (Also known as the Assertion Consumer Service URL)
Entity ID
https://slack.com
SAML logout endpoint
https://yourdomain.slack.com/sso/saml/logout
Bear in mind: Slack does not support single logout or session duration configured in your IdP.
Considerations
Slack supports HTTP POST binding, not HTTP REDIRECT. You must configure HTTP POST bindings in the IdP metadata.
Your IdP must ensure a user is both authenticated and authorised before sending an assertion. If a user isn’t authorised, assertions should not be sent. We recommend your identity provider to redirect people to an HTTP 403 page or something similar.
Slack requires that the SAML response is signed, and you will need to paste a valid X.509 .pem Certificate to verify your identity. This is different from your SSL certificate.
End-to-end encryption key
If you require an end-to-end encryption key for your IDP, you can find a certificate by clicking the Advanced Options button located in your workspace's SSO settings. You can then tick the Sign AuthnRequest preference to reveal Slack's public encryption key.
Note: If you want to connect your Active Directory Federation Services (ADFS) instance, read ADFS single sign-on for details.