For example, here's a VM asking the metadata service about its hostname:
$ curl http://169.254.169.254/latest/meta-data/hostname <html><body><h1>504 Gateway Time-out</h1> The server didn't respond in time. </body></html>
I'm guessing this has to do with recent firewall changes, for example
This means we can't create new working VMs at all. This is likely also breaking Magnum and Heat. Trove seems to still work, I think because it uses config-drive rather than the metadata service.