aws_networkfirewall_rule_group: Cannot reference rule_variables in rule_variables

[AL1060005]

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Terraform CLI and Terraform AWS Provider Version

Provider version: 3.70.0

Description

The aws_networkfirewall_rule_group module allows to define a rule_variables block of ip sets for suricata rules.

The suricata format allows to reference other variables, and to negate them. This is both valid in the AWS console and CloudFormation, but unfortunately doesn't work here.

In this module, IP sets are expected to be in CIDR format only (i.e. A.B.C.D/X) only, with no way to reference other variables.

Expected working example

resource "aws_networkfirewall_rule_group" "example" {
  capacity = 100
  name     = "example"
  type     = "STATEFUL"
  rule_group {
    rule_variables {
      ip_sets {
        key = "WEBSERVERS_HOSTS"
        ip_set {
          definition = ["10.0.0.0/16", "10.0.1.0/24", "192.168.0.0/16"]
        }
      }
      ip_sets {
        key = "EXTERNAL_HOSTS"
        ip_set {
          definition = ["!WEBSERVERS_HOSTS"]
        }
      }
    }
  }
}

Actual Behavior

Error:

╷
│ Error: "!WEBSERVERS_HOSTS" is not a valid CIDR block: invalid CIDR address: !WEBSERVERS_HOSTS
│
│ with module.basic_example.aws_networkfirewall_rule_group.example,
│ on ../../main.tf line 28, in resource "aws_networkfirewall_rule_group" "example":
│ 28: rule_variables {

[anGie44]

Hi @AL1060005 , thank you for raising this issue. From the API specs, an ip_set definition seems to be defined as The list of IP addresses and address ranges, in CIDR notation. but oddly enough the pattern is specified as ^.*$ which i believe should allow for referencing other variables like WEBSERVERS_HOST. This can be addressed by adjusting the validation to the new regex pattern instead of just checking for valid CIDR addresses as seen here in the resource code:

terraform-provider-aws/internal/service/networkfirewall/rule_group.go

Lines 81 to 93 in 1915c4c

	"ip_set": {
	Type: schema.TypeList,
	Required: true,
	MaxItems: 1,
	Elem: &schema.Resource{
	Schema: map[string]*schema.Schema{
	"definition": {
	Type: schema.TypeSet,
	Required: true,
	Elem: &schema.Schema{
	Type: schema.TypeString,
	ValidateFunc: verify.ValidIPv4CIDRNetworkAddress,
	},

So ValidateFunc: validation.StringMatch(regexp.MustCompile(`^.*$`), ""), may be the better solution.

[github-actions]

This functionality has been released in v3.71.0 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]

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