A practical checklist for autoscaling

The version of this that works is simpler than the version most people imagine. Run through this the next time autoscaling comes up.

Operability is a feature, and it has to be built rather than bought. The teams that stay on top of it are the ones who put it on a calendar rather than a wish list.

The checklist

• Scaling rules need testing under real load, not in theory
• Scaling up is easy, scaling down safely is the hard part
• A slow dependency will not scale with you
• Someone is named as the owner
• There is a date to review it again

What it costs to ignore

Scaling rules need testing under real load, not in theory. This is the sort of thing that compounds, quietly, in both directions. If it only works because one person remembers to do something, it does not work yet.

The short version

The bill is a design document: it tells you exactly what your architecture actually does. Three things worth confirming about autoscaling before you move on:

• Someone can say what the current setup is without going to look
• Scaling rules need testing under real load, not in theory — and you know whether that is true here
• There is a way to tell whether the last change to this helped

If you are not sure where your systems currently stand on this, it takes us about an hour to find out.