Kubernetes with AWS Elastic Block Storage
We opened an issue to discuss this: https://github.com/kubernetes/kubernetes/issues/13858
The recommended way to go here is to use IAM instance profiles. kube-up does configure this for you, and if you're not using kube-up I recommend looking at it to emulate what it does!
Although we did recently merge in support for using a .aws credentials file, I don't believe it has been back-ported into any release, and it isn't really the way I (personally) recommend.
It sounds like you're not using kube-up; you may find it easier if you can use that (and I'd love to know if there's some reason you can't or don't want to use kube-up, as I personally am working on an alternative that I hope will meet everyone's needs!)
I'd also love to know if IAM instance profiles aren't suitable for you for some reason.