This is a great list! One thing I would add, once you have everything on this list, is a way to experiment on your changes. Instead of flipping a flag, seeing y

This is a great list! One thing I would add, once you have everything on this list, is a way to experiment on your changes. Instead of flipping a flag, seeing your error rate jump, and flipping it back, you run an experiment where to flip the flag on 0.1% of requests. Now you can compare this traffic to a control group, and aren't stuck wondering "did errors go up by 5% during our rollout because we broke things, or by chance?". If things look as expected at 0.1% you can ramp to 1%, then 10% before releasing.