Comment by flaminHotSpeedo
2 hours ago
Like the other poster said, roll back should be the right answer the vast majority of the time. But it's also important to recognize that roll forward should be a replacement for the deployment you decided not to roll back, not a parallel deployment through another system.
I won't say never, but a situation where the right answer to avoid a rollback (that it sounds like was technically fine to do, just undesirable from a security/business perspective) is a parallel deployment through a radioactive, global blast radius, near instantaneous deployment system that is under intense scrutiny after another recent outage should be about as probable as a bowl of petunias in orbit
Is a roll back even possible at Cloudflare's size?
With small deployments it usually isn't too difficult to re-deploy a previous commit. But once you get big enough you've got enough developers that half a dozen PRs will have been merged since the start of the incident and now. How viable is it to stop the world, undo everything, and start from scratch any time a deployment causes the tiniest issues?
Realistically the best you're going to get is merging a revert of the problematic changeset - but with the intervening merges that's still going to bring the system in a novel state. You're rolling forwards, not backwards.
If companies like Cloudflare haven't figured out how to do reliable rollbacks, there seems little hope for any of us.
I'd presume they have the ability to deploy a previous artifact vs only tip-of-master.