Hard-coded bastion instance type forces HVM EC2 nodes

[gustav-b]

Because there is only one parameter to set the CoreOS AMI (--ami) for all nodes and this value is used to create the bastion instance which is hard-coded to be t2.micro, this means that the AMI must be of HVM type. By extension this means that no PV-only instance types can be used (e.g. t1.micro, m1.small and m1.medium) as the argument to --instance-size.

If this is intended I suggest that it should be documented.

[jimmycuadra]

Thanks for bringint this up. It's not so much that it's intended than it is that almost all the code in kaws is based on how we deploy Kubernetes clusters at InQuicker. As an open source tool, we do want parts of it to be configurable, but not at huge expense to the complexity of the tool for our purposes. Could you say some more about your use case and why you want to use PV instances?

[gustav-b]

Thanks for a useful tool,

I have no actual use case that requires PV instances – I think the HVM limitation is fine if it simplifies the tool. I was just a bit surprised when I tried creating a cluster with m1.small and noticed that it failed because the t2.micro instance (that I didn't declare) required a HVM AMI. So maybe it should be documented as a requirement in the cluster reference?

[jimmycuadra]

Agreed, it should be documented. Thanks!