Packer: Amazon Builders on t3 instances have unlimited credits enabled by default

[ricardclau]

This is related to https://github.com/hashicorp/packer/issues/6260 and it happens with all packer versions

AWS recently launched t3 instances which have better network performance (and are slightly cheaper) than the previous t2 family

However, they come with a hidden surprise, unlimited credits seems to be on by default

I guess it should be a relatively easy fix. Code in the mentioned issue should be slightly modified so that unlimited credits is explicitly set to false by default and only set to true if the packer user decides to

If nobody wants to pick this up, I may have some time to work on it!

[rickard-von-essen]

_Unlimited mode_ is the AWS default, we should retain the AWS defaults.

See https://aws.amazon.com/ec2/instance-types/t3/

[ricardclau]

Yeah, I see your point respecting AWS defaults.

Maybe docs should be improved https://www.packer.io/docs/builders/amazon-ebs.html#enable_t2_unlimited as they only cover t2 family

[rickard-von-essen]

We need to rework this functionality a bit. The option doesn't reflect what it actually does.. 😢

[rickard-von-essen]

This was introduced in #6265

[eedwards-sk]

Error: T2 Unlimited enabled with a non-T2 Instance Type: t3.micro

from a usability standpoint, makes zero sense that this is configurable for t2 and not t3. It's the same concept.

from an api standpoint, any PRs to make this consistent between the two would be ideal...

in terraform, it's configured with credit_specification and no mention of t2 or t3 at all

edit: for clarity, please allow us to disable bursting on t3 if we want, but leave the defaults