Here is a list of resources that have changed behavior between v1.x and 2.x
aptly_mirror resource architectures property has changed in a way that it now requires a array instead of a string.
aptly_publish Resource architectures property no longer explicitly defaults to ['amd64'] thus no longer always overriding the global aptly configuration/cookbook attribute value of default['aptly']['architectures']. This mimics aptly's native behavior.