Hi David,
Thanks for replying so quickly. I'm supplying the subnet ids as a comma-separated list (subnet-<string1>, subnet-<string2>, subnet-<string3>). All of the subnets are part of the same VPC but belong to different AZs.
subnet-<string1> is part of AZ us-east-1a
subnet-<string2> is part of AZ us-east-1b
subnet-<string3> is part of AZ us-east-1c
I am also listing the three AZs as a comma-separated list in the "availability zone" text box ie. us-east-1a, us-east-1b, us-east-1c
It is possible that I have misunderstood the new feature. Do the subnets have to be part of the same availability zone?
This could be useful for us as well. It is a problem to hardcode to a single availability zone / vpc subnet for spot instances as there could be price spikes and capacity bottlenecks.
Tried comma separated subnet IDs for VPC. It did not work