When we click on a link in our portal I want to show redash dashboard after proper authentication in the background into redash (not the sharable public dashboard URL). Can someone help me figure how to achieve this?

Redash does not and cannot support this. A few people tried in the past and ran into issues with x-frame headers and the security rules in Chrome specifically that made it impossible to pass the right session cookies between the Redash iframe and the host page. Speaking generally: Redash isn’t built for embedded analytics.

Thanks for your reply. Is it at least possible to authenticate from another web application into redash using SAML or OAuth.

Yes, Redash works with SAML and Google Login.

Is there any official step by step documentation for SAML or OAuth. I found https://redash.io/help/user-guide/users/authentication-options, but it only have minimal details and its using third party services like Okta for authentication. I am looking for a solution that doesn’t involve a third party service. However the final objective is to show the user his dashboard in my web app after authenticating to redash.

I don’t think there’s a generic document for SAML. But the generic version is easy to glean from the references in the link you sent. NameID is email address. New users should all be part of the default group. The rest is just configuring the URL’s that the IDP and SP use to communicate with one another.