This is just sad.
Yeah zero downtime. You ship out the new features but gate them using some system you can control. When all the new features are shipped you turn up the new features until it gets to 100%. This lets you observe the real world behavior of the new features if they don’t cache well or cause 500s or what have you you can turn it off without having to ship new code.
Also if you keep all these feature flags, if you have a situation where you have capacity problems you can turn down features for the survival of the service as a whole.
I had the wide genesis also, but I had the newer CD so my genesis hanged off the side.
Explaine who was fixing those things after fighting that red dude and the witch