Call an access policy based on iRule condition

Hi Team,

We have a requirement to call an access policy that does SAML auth only based on a condition on iRule. For example, we have to do SAML auth only if a cookie is not present. Could you please guide us on how to achieve this? i.e., If the required cookie is present, then allow access to the pool. Else, do a SAML auth.

I tried assigning the iRule that checks for the cookie and the access policy that does SAML auth. But, if the cookie is not present how do I call access policy?

Thanks, Neeharika