Prefix List ressource won't allow adding an entry and changing the maximum number of entries at the same time

[ingoaf]

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Terraform CLI and Terraform AWS Provider Version

windows_amd64
terraform v1.2.7

terraform providers
Providers:
├── provider[registry.terraform.io/hashicorp/aws] 4.29.0

Affected Resource(s)

• aws_ec2_managed_prefix_list

Terraform Configuration Files

Please include all Terraform configurations required to reproduce the bug. Bug reports without a functional reproduction may be closed without investigation.

resource "aws_ec2_managed_prefix_list" "my_prefix_list" {
  name           = "my-prefix-list"
  address_family = "IPv4"
  max_entries    = 1

  entry {
    cidr        = "172.217.0.0/32"
    description = "test-block-1"
  }
}

Expected Behavior

The execution of terraform apply + confirmation should have worked.

Actual Behavior

Received an error: error updating EC2 Managed Prefix List (pl-0625f89a976b5cd): InvalidParameterCombination: You cannot modify the entries and the maximum entries for the prefix list in the same request.

Steps to Reproduce

1. terraform apply, confirm
2. change the terraform configuration to

resource "aws_ec2_managed_prefix_list" "my_prefix_list" {
  name           = "my-prefix-list"
  address_family = "IPv4"
  max_entries    = 2 // increased by one

  entry {
    cidr        = "172.217.0.0/32"
    description = "test-block-1"
  }

  // added this entry
  entry {
    cidr        = "216.58.190.0/32"
    description = "test-block-2"
  }
}

3. terraform apply, confirm

References

[drewmullen]

The API will not allow updating max entries and entry changes at the same time. the resource code needs to account for:

• if MaxEntries is increasing, call Modify to increase MaxEntries prior to adding entries
• if MaxEntries is decreasing, call Modify to decrease MaxEntries after removing entries

This means that if MaxEntries and Entries are changing in the same call, terraform will need to make 2 modify calls

[kevindashton]

related to #25235

[kevindashton]

Seems like this is a bug/defect, as we were blocked from being able to apply a simple additional inline entry due to these EC2 API errors. A potential work around was to use the aws_ec2_managed_prefix_list_entry resources, but that causes rather extreme performance issues and timeouts during terraform apply due to EC2 API service throttling caused by managing each prefix list entry independently.

[github-actions]

This functionality has been released in v4.32.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.