Do you find that you clean at home the fastest when you know you have an imminent visit by a friend? Its amazing how fast you can whip around the house and get things ready in time for the knock on the door.

Spot instances are one of my many favorite things about AWS. They are for people who really want to cost optimize and have a workload that can match its model. The main element to be aware of with Spot is that it is a market where you place a bid for how much you are willing to pay for the resource, if the market changes and the amount you are willing to pay is no longer high enough your instance will be taken away (or reclaimed if you want a nice way of saying it).

How fast is the instance reclaimed? Well before the start of the year it was reclaimed fast, essentially no notice. Now you get a two minute warning before they are terminated. Enough time to tidy the house before that knock on the door. Many people have not noticed this change as it occurred very early in January whilst many people were away on their Christmas holidays. Who reads the AWS blog on their holidays?

The notice period provides you the opportunity to automate performing tasks such as saving state, coping off data such as logs, or numerous other things which may be part of stopping processing.

How do you know when your two minutes notice period starts? You can monitor for the existence of the metadata field http://169.254.169.254/latest/meta-data/spot/termination-time. Its recommended you check every 5 seconds, but thats really up to you.

If you need to be aware of the status from outside of the instance each spot request has a bid status which will change to marked-for-termination during the notice period. See all the details at http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-bid-status.html

You can read more about all of this on the blog announcement. For details on Spot see the documentation at http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-spot-instances.html.

Rodos