[Enhancement]: Option to skip iops validation for unknown ebs volume types

[willgorman]

Description

The provider currently prevents iops from being set on volume types other than io1, io2, and gp3:

terraform-provider-aws/internal/service/ec2/ebs_volume.go

Lines 349 to 367 in 08b1191

	// Iops is required for io1 and io2 volumes.
	// The default for gp3 volumes is 3,000 IOPS.
	// This parameter is not supported for gp2, st1, sc1, or standard volumes.
	// Hard validation in place to return an error if IOPs are provided
	// for an unsupported storage type.
	// Reference: https://github.com/hashicorp/terraform-provider-aws/issues/12667
	switch volumeType {
	case awstypes.VolumeTypeIo1, awstypes.VolumeTypeIo2:
	if iops == 0 {
	return fmt.Errorf("'iops' must be set when 'type' is '%s'", volumeType)
	}
	case awstypes.VolumeTypeGp3:
	default:
	if iops != 0 {
	return fmt.Errorf("'iops' must not be set when 'type' is '%s'", volumeType)
	}
	}

This presents a problem when using the provider with alternate backends that support the AWS EBS APIs but offer additional volume types, some of which do allow specifying provisioned iops. The purpose for this issue is to see if there is support for opening a PR that makes it possible to allow iops to be provided for other volume types. The implementation for this PR could be one of the following:

• Allow iops to be provided for any volume type that is not one of the official AWS volume types
• Support a flag/option/environment variable that allows a user to provide a list of volume types that support iops
• Support a flag/option/environment variable that disables the volume type check

This would also be beneficial if AWS adds another new volume type in the future that supports provisioned iops. Currently the provider would have to be updated to allow iops to be used with the new volume type but with this change it would be possible to use the new volume type without upgrading the provider version.

Affected Resource(s) and/or Data Source(s)

• aws_ebs_volume

Potential Terraform Configuration

resource "aws_ebs_volume" "a-volume" {
  availability_zone = "us-east-1a"
  size              = 50
  type              = "definitely-not-an-aws-volume-type"
  iops              = 5000
}

References

No response

Would you like to implement a fix?

Yes

[github-actions]

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