I'm moving example.com from an external (non-Google) hosting provider into GCP.
When setting up the load balancer, I noticed that I have to point example.com to the load balancer in order for the Google managed certificate to validate.
I'm supposed to just change the A record of example.com to the (static) IP of the new load balancer - then it will validate.
The problem is that I already have a lot of traffic to example.com, requests that happen after example.com starts pointing to the load balancer, but before the certificate is validated will generate SSL errors, and very unhappy users.
Has anyone solved this? I know there are ways to avoid downtime when rotating certificates, but there must be some way to migrate large sites without downtime?