Question

A new AWS ELB feature, connection draining, was recently announced.

http://aws.amazon.com/about-aws/whats-new/2014/03/20/elastic-load-balancing-supports-connection-draining/

Apparently this works with Auto Scaling Groups - instances are drained before being removed, but does that also apply to spot instances that are being terminated by AWS due to a rising spot price?

Was it helpful?

Solution

Nothing definitive I could find, but from my reading on this, I think the answer is almost definitely no. Spot instances are different animals than regular instances, and the way the connection draining works you can specify upto 60 minute delay before your connection-drained enabled instance gets terminated when it becomes unhealthy - if AWS was to allow this added layer of safety to spot instances, it would completely up-end the way spot instances are used and how they are positioned.

The trade-off for using spot instances has always been, "you can pay a fraction of the cost, but you risk being terminated at any instant without warning"...if they added an up to 60 minute 'warning' to spot instances, while it would be fantastic from the end-users point of view, I think it would severely eat into AWS's on-demand and reserved instance pricing model and thus they probably won't support this anytime soon (unless forced to by competitive pressure).

EDIT 1/6/2015: now, almost a year later, AWS has indeed added a 'two minute warning' for EC2 spot instance termination. https://aws.amazon.com/blogs/aws/new-ec2-spot-instance-termination-notices/

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