According to this link, I can use another identity provider other than the out of the box providers like Active Directory, Google, Facebook. I have an IdentityServer4 hosted as
I just stumbled on the same issue, at the moment there is no support but you can vote for this implementation via this uri: Enable custom 3rd party authentication providers
Currently I'm busy with a POC so I needed this functionality and I stumbled upon this post: Secure Azure Functions with JWT access tokens This works perfect with my custom token provider. Hopefully it does too for you.