data/aws: Explicitly set ebs_optimized true

[wking]

I'd have expected this to be the default for instance types where EBS-optimized is the default (like m4.large). But apparently not:

$ AWS_PROFILE=ci aws ec2 describe-instances --instance-ids i-076622e249b75a673 --query 'Reservations[0].Instances[0].{InstanceType: InstanceType, EbsOptimized: EbsOptimized}' --output json
{
    "EbsOptimized": false,
    "InstanceType": "m4.large"
}

Docs for the Terraform property are here.

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[staebler]

I am curious whether this is a deficiency in the AWS instance description. From the AWS web console, you are not allowed to un-check the EBS-optimized box when selecting a m4.large instance.

What will happen if the instance type passed into the bootstrap or master module is one that does not accept EBS optimization? I don't suppose that those instance types are even relevant any more.

[cgwalters]

The TF docs explicitly say:

Note that if this is not set on an instance type that is optimized by default then this will show as disabled but if the instance type is optimized by default then there is no need to set this and there is no effect to disabling it.

But it can't hurt to set it either.

[wking]

The TF docs explicitly say...

Heh, I somehow skimmed over that sentence. And taking another look at the AWS docs:

For instance types that are EBS–optimized by default, there is no need to enable EBS optimization and no effect if you disable EBS optimization.

So I'm closing this to keep the code simple and avoid @staebler's point about supporting instance types that don't do EBS-optimization.