AWS::WAF::SizeConstraintSet - AWS CloudFormation
SyntaxPropertiesReturn valuesExamples

AWS::WAF::SizeConstraintSet

Note

AWS WAF Classic support will end on September 30, 2025.

This is AWS WAF Classic documentation. For more information, see AWS WAF Classic in the developer guide.

For the latest version of AWS WAF , use the AWS WAFV2 API and see the AWS WAF Developer Guide. With the latest version, AWS WAF has a single set of endpoints for regional and global use.

A complex type that contains SizeConstraint objects, which specify the parts of web requests that you want AWS WAF to inspect the size of. If a SizeConstraintSet contains more than one SizeConstraint object, a request only needs to match one constraint to be considered a match.

Syntax

To declare this entity in your AWS CloudFormation template, use the following syntax:

JSON

{
  "Type" : "AWS::WAF::SizeConstraintSet",
  "Properties" : {
      "Name" : String,
      "SizeConstraints" : [ SizeConstraint, ... ]
    }
}

YAML

Type: AWS::WAF::SizeConstraintSet
Properties:
  Name: String
  SizeConstraints: 
    - SizeConstraint

Properties

Name

The name, if any, of the SizeConstraintSet.

Required: Yes

Type: String

Pattern: .*\S.*

Minimum: 1

Maximum: 128

Update requires: Replacement

SizeConstraints

The size constraint and the part of the web request to check.

Required: Yes

Type: Array of SizeConstraint

Update requires: No interruption

Return values

Ref

When you pass the logical ID of this resource to the intrinsic Ref function, Ref returns the resource physical ID, such as 1234a1a-a1b1-12a1-abcd-a123b123456.

For more information about using the Ref function, see Ref.

Fn::GetAtt

Examples

Define a Size Constraint

The following example checks that the body of an HTTP request equals 4096 bytes.

JSON

"MySizeConstraint": {
  "Type": "AWS::WAF::SizeConstraintSet",
  "Properties": {
    "Name": "SizeConstraints",
    "SizeConstraints": [
      {
        "ComparisonOperator": "EQ",
        "FieldToMatch": {
          "Type": "BODY"
        },
        "Size": "4096",
        "TextTransformation": "NONE"
      }
    ]
  }
}

YAML

  MySizeConstraint: 
    Type: "AWS::WAF::SizeConstraintSet"
    Properties: 
      Name: "SizeConstraints"
      SizeConstraints: 
        - 
          ComparisonOperator: "EQ"
          FieldToMatch: 
            Type: "BODY"
          Size: "4096"
          TextTransformation: "NONE"

Associate a SizeConstraintSet with a Web ACL Rule

The following example associates the MySizeConstraint object with a web ACL rule.

JSON

"SizeConstraintRule" : {
  "Type": "AWS::WAF::Rule",
  "Properties": {
    "Name": "SizeConstraintRule",
    "MetricName" : "SizeConstraintRule",
    "Predicates": [
      {
        "DataId" : {  "Ref" : "MySizeConstraint" },
        "Negated" : false,
        "Type" : "SizeConstraint"
      }
    ]
  }
}

YAML

SizeConstraintRule: 
  Type: "AWS::WAF::Rule"
  Properties: 
    Name: "SizeConstraintRule"
    MetricName: "SizeConstraintRule"
    Predicates: 
      - 
        DataId: 
          Ref: "MySizeConstraint"
        Negated: false
        Type: "SizeConstraint"

Create a Web ACL

The following example associates the SizeConstraintRule rule with a web ACL. The web ACL blocks all requests except for requests with a body size equal to 4096 bytes.

JSON

"MyWebACL": {
  "Type": "AWS::WAF::WebACL",
  "Properties": {
    "Name": "Web ACL to allow requests with a specific size",
    "DefaultAction": {
      "Type": "BLOCK"
    },
    "MetricName" : "SizeConstraintWebACL",
    "Rules": [
      {
        "Action" : {
          "Type" : "ALLOW"
        },
        "Priority" : 1,
        "RuleId" : { "Ref" : "SizeConstraintRule" }
      }
    ]
  }
}

YAML

MyWebACL: 
  Type: "AWS::WAF::WebACL"
  Properties: 
    Name: "Web ACL to allow requests with a specific size"
    DefaultAction: 
      Type: "BLOCK"
    MetricName: "SizeConstraintWebACL"
    Rules: 
      - 
        Action: 
          Type: "ALLOW"
        Priority: 1
        RuleId: 
         Ref: "SizeConstraintRule"