[Bug]: aws_subnet enable_lni_at_device_index doesn't work when clearing the value

[fh-yuxiao-zeng]

Terraform Core Version

1.4.5

AWS Provider Version

4.64.0

Affected Resource(s)

aws_subnet (enable_lni_at_device_index)

Expected Behavior

When I specify a subnet without enable_lni_at_device_index, the ModifySubnetAttribute API call should include DisableLniAtDeviceIndex parameter, and it should succeed.

Actual Behavior

Terraform fails with an error.

Relevant Error/Panic Output Snippet

│ Error: modifying EC2 Subnet (subnet-xxx) EnableLniAtDeviceIndex: InvalidParameterValue: lni-at-device-index must be less than or equal to 64 and greater than or equal to 1
│ 	status code: 400, request id: xxx
│ 
│   with aws_subnet.xxx,
│   on xxx.tf line 1, in resource "aws_subnet" "xxx":
│    1: resource "aws_subnet" "xxx" {
│ 
╵
Error: Terraform exited with code 1.
Error: Process completed with exit code 1.

Terraform Configuration Files

resource "aws_subnet" "xxx" {
  vpc_id      = xxx
  outpost_arn = xxx

  cidr_block = "10.0.0.0/24"

  assign_ipv6_address_on_creation = true
  ipv6_cidr_block                 = xxx

  private_dns_hostname_type_on_launch            = "resource-name"
  enable_resource_name_dns_a_record_on_launch    = true
  enable_resource_name_dns_aaaa_record_on_launch = true

  # note that enable_lni_at_device_index is not set
}

Steps to Reproduce

1. Manually create a subnet
2. Use AWS CLI to set lni_at_device_index to be 1: aws ec2 modify-subnet-attribute --subnet-id subnet-xxx --enable-lni-at-device-index 1
3. Apply the terraform config above

Debug Output

No response

Panic Output

No response

Important Factoids

No response

References

https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_ModifySubnetAttribute.html

When the LNI attribute needs to be cleared, the request should have DisableLniAtDeviceIndex set to true.

Would you like to implement a fix?

None

[github-actions]

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[ewbankkit]

Relates #30798.
Relates #30779.
Relates #25631.

[github-actions]

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