partitions size fixed in 8Gb
There's an issue with current Jessie images on Amazon: Partitions have a fixed size of 8Gb. No matter the storage size you choose, it will end up with 8Gb.
I'm writing here because there are things that the folks at bootstrap-vz can not do, like upgrading cloud-utils package in Jessie.
Please, take a look at this issue above (to avoid repeating myself here). There I suggest how this can be fixed. I think this is a serious issue.