SAM API Gateway with Cloudformation WAFRegional

Question

To secure our API, I'm trying to deploy a WAFRegional with a RateBasedRule. The API Gateway is located in a SAM template wherein I have also a nested stack for the child template holding the WAFRegional configurations. The child template for the WAFRegional configuration is provided below. What happens during the ExecuteChangeSet phase is the following:

1. CamerasIpSet is created

2. CamerasRateRule is created

3. WAFCamerasWebACL CREATE_FAILED: The referenced item does not exist. (Service: AWSWAFRegional; Status Code: 400; Error Code: WAFNonexistentItemException

I found the following post from about 2 months ago where someone has the same issue when using Serverless: https://forum.serverless.com/t/dependon-api-gateway-deployment/7792

What am I missing out on here?

AWSTemplateFormatVersion: '2010-09-09'
Description: 'Template for WAF Configuration'
Parameters:
  CamerasApi:
    Description: "Arn of the Cameras Api"
    Type: String
    Default: cameras-api-dev
  StageName:
    Description: "Stage name of the Cameras Api"
    Type: String
    Default: v
  Blocking:
    Description: "Number of calls per 5 minutes for WAF IP blocking."
    Type: Number
    Default: 2000
  EnvironmentType:
    Type: String
    Default: "dev"
    Description: "Type of environment: dev, staging or prod."


Resources:
  WAFCamerasWebACL:
    Type: AWS::WAFRegional::WebACL
    DependsOn: CamerasRateRule
    Properties:
      DefaultAction:
        Type: ALLOW
      MetricName: !Join ['', ['IPBlockingMetric', !Ref EnvironmentType]]
      Name: !Join ['', ['IPBlockingACL', !Ref EnvironmentType]]
      Rules:
        -
          Action:
            Type: "BLOCK"
          Priority: 1
          RuleId: !Ref CamerasRateRule

  CamerasRateRule:
    Type: AWS::WAFRegional::RateBasedRule
    Properties:
      MetricName: UnallowedAccessCount
      Name: FiveMinuteRule
      RateKey: IP
      RateLimit: !Ref Blocking
      MatchPredicates:
      -
        DataId: !Ref CamerasIpSet
        Negated: false
        Type: "IPMatch"

  CamerasIpSet:
    Type: AWS::WAFRegional::IPSet
    Properties:
      Name: !Join ['-', ['IpBlacklist', !Ref EnvironmentType]]


  MyWebACLAssociation:
    Type: AWS::WAFRegional::WebACLAssociation
    Properties:
      ResourceArn: !Sub arn:aws:apigateway:${AWS::Region}::/restapis/${CamerasApi}/stages/${StageName}
      WebACLId: !Ref WAFCamerasWebACL

Outputs:
  WebACL:
    Description: Name of the web ACL
    Value: !Ref WAFCamerasWebACL

Answer 1

I finally resolved the issue with the help of the AWS customer service. This is a limitation they have with CloudFormation when dealing with AWS::WAFRegional::RateBasedRule.

Despite the fact that CloudFormation supports creating WAF regional rate-based rules, the association of them with a Web ACL is not currently supported. If you observe link [1] below, you will realize that: "To add the rate-based rules created through CloudFormation to a web ACL, use the AWS WAF console, API, or command line interface (CLI)."

[1] AWS::WAFRegional::RateBasedRule: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-wafregional-ratebasedrule.html

I used the Cloudformation template to generate the WebACL, the RateBasedRule, and the association of the WebACL with my APIGW. Using CodeBuild in our CI/CD pipeline, I'm now adding the RateBasedRule to the WebACL by using the CLI command aws waf-regional update-web-acl.

Answer 2

I ran in the same issue and I solve the problem with WAFv2

AWSTemplateFormatVersion: '2010-09-09'
Description: 'Template for WAF Configuration'
Parameters:
  CamerasApi:
    Description: "Arn of the Cameras Api"
    Type: String
    Default: YOUR-API-ID
  StageName:
    Description: "Stage name of the Cameras Api"
    Type: String
    Default: YOUR-Stage
  Blocking:
    Description: "Number of calls per 5 minutes for WAF IP blocking."
    Type: Number
    Default: 2000
  EnvironmentType:
    Type: String
    Default: Prod
    Description: "Type of environment: dev, staging or prod."


Resources:
  WAFCamerasWebACL:
    Type: AWS::WAFv2::WebACL
    Properties:
      Name: ExampleWebACL
      Description: This is an example WebACL
      Scope: REGIONAL
      DefaultAction: 
        Allow: {}
      VisibilityConfig:
        SampledRequestsEnabled: true
        CloudWatchMetricsEnabled: true
        MetricName: ExampleWebACLMetric
      Rules:
        - Name: RulesTest
          Priority: 0
          Action:
           Block: {}
          VisibilityConfig:
            SampledRequestsEnabled: true
            CloudWatchMetricsEnabled: true
            MetricName: test
          Statement:
            RateBasedStatement:
              Limit: 100
              AggregateKeyType: IP

  MyWebACLAssociation:
    Type: AWS::WAFv2::WebACLAssociation
    Properties:
      ResourceArn: !Sub arn:aws:apigateway:${AWS::Region}::/restapis/${CamerasApi}/stages/${StageName}
      WebACLArn: !GetAtt  WAFCamerasWebACL.Arn

Outputs:
  WebACL:
    Description: Name of the web ACL
    Value: !Ref WAFCamerasWebACL