If I have a VXLAN setup, you cannot peer OSPF from a VLAN SVI because of the shared IP/MAC on the VTEPS. So how would you go about setting up an OSPF adjacency from lets say a virtual firewall/switch without having to use any additional dedicated network interfaces?
My guess is to have a dedicated vlan SVI with a /31 range and advertise that into the distributed switch, and create a port group for that vlan? Any other way you guys can think of?
You need additional network interfaces. That's the end of it.
Look at NSX to N9K reference design here, the peering to the ESG is exactly what you're referring to.
https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/whitepaper/products/nsx/design-guide-for-nsx-with-cisco-nexus-9000-and-ucs-white-paper.pdf (https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/whitepaper/products/nsx/design-guide-for-nsx-with-cisco-nexus-9000-and-ucs-white-paper.pdf)
Note: The design is a bit out of date in that you could now peer through a vPC without a dedicated VLAN, but I've not seen it in the wild personally, everyone I've seen is still running L3 through dedicated VLANs because that's how we've always done it lol