Spot price for master about kops

[justinsb]

You can now set nodes or masters to use spot instances, using this: https://github.com/kubernetes/kops/blob/master/docs/instance_groups.md#converting-an-instance-group-to-use-spot-instances

I'm not sure that running 3 masters as spot instances is better than just running a single instance as a non-spot instance if availability is the concern. But you can at least do it now!

My fear with spot instances is that in the event an AZ fails, you lose that master. Then everyone else's autoscaling groups put more load into the surviving AZs, and the spot instance price in those AZs goes way up, or spot instances simply become unavailable. In other words that a single AZ failure would result in a failure of 2 or all of your masters. But there isn't a huge amount of data here.

If you try it let us know how it goes - it's definitely useful if you're just testing HA master and want to save some money!

Closing for now, as the feature is implemented. We can continue the discussion though if anyone wants to - it might be that we end up creating a "best practice" document.