Shard Allocation Awareness in ec2

Hi,

I'm setting up elastic search cluster in ec2

This is the discovery configuration

discovery:
type: ec2
ec2:
groups: elasticsearch
host_type: private_ip
availability_zones: us-east-1a,us-east-1c,us-east-1d
any_group: false
ping_timeout: 5
tag:
stage: dev

Now

From the documentation it's not clear if Cluster module allocation
awareness makes use of the fact that node is running in ec2 - which
seems natural to do.

So the question is do I need to set routing.allocation.awareness
explicitly like this:

cluster:
name: dev
routing.allocation.awareness:
attributes: availability_zone
force.availability_zone.values:
us-east-1a,us-east-1c,us-east-1d

node:
availability_zone: us-east-1a

Or this could be simplified or completely omitted with same effect?
Like specifying node.availability_zone - seems to be unneeded - as we
already know such info from the ec2 discovery module.

Thanks
Alex