This is impressive! I know others are questioning the "no downtime" bit, but that is why service level objectives exist -- because it really depends on the customer experience.

If you managed to have a cutover with no noticeable dip in business metrics (aka the users didn't notice) then I'd call that a no-downtime upgrade!

Very clever on the improvement over Lyft's methods. Thanks for the writeup. Now maybe someone can get it down from 3 seconds of pausing. :)