I deployed Spinnaker to GKE using hal and confirmed the UI was working locally via port forwarding by hal deploy connect.

I then proceeded to implement IAP for public access via protected endpoint. The authentication workflow appears to behave as expected as I am successfully routed through the corporate login and MFA auth screens. The Spinnaker "Hello" screen briefly flashes, however, before quickly returning to the following error:

Service Unavailable The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Apache/2.4.38 (Debian) Server at spinnaker-dev.endpoints.xxxxxxxxxxxx.cloud.goog Port 9000

I have reviewed the container logs associated with each workload, Gate, Deck, Clouddriver, etc.. with no material results.