AWS::Config::ConfigRule

The AWS::Config::ConfigRule resource uses an AWS Lambda (Lambda) function that evaluates configuration items to assess whether your AWS resources comply with your specified configurations. This function can run when AWS Config detects a configuration change or delivers a configuration snapshot. The resources this function evaluates must be in the recording group. For more information, see Evaluating AWS Resource Configurations with AWS Config in the AWS Config Developer Guide.

Syntax

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

JSON


{
  "Type" : "AWS::Config::ConfigRule",
  "Properties" : {
    "ConfigRuleName" : String,
    "Description" : String,
    "InputParameters" : { ParameterName : Value },
    "MaximumExecutionFrequency" : String,
    "Scope" : Scope,
    "Source" : Source
  }
}

YAML


Type: AWS::Config::ConfigRule
Properties:
  ConfigRuleName: String
  Description: String
  InputParameters:
    ParameterName : Value
  MaximumExecutionFrequency: String
  Scope:
    Scope
  Source:
    Source

Properties

ConfigRuleName

A name for the AWS Config rule. If you don't specify a name, AWS CloudFormation generates a unique physical ID and uses that ID for the rule name. For more information, see Name Type.

Required: No

Type: String

Update requires: Replacement

Description

A description about this AWS Config rule.

Required: No

Type: String

Update requires: No interruption

InputParameters

Input parameter values that are passed to the AWS Config rule (Lambda function).

Required: No

Type: JSON object

Update requires: No interruption

MaximumExecutionFrequency

The maximum frequency at which the AWS Config rule runs evaluations. For valid values, see the ConfigRule data type in the AWS Config API Reference.

If the rule runs an evaluation when AWS Config delivers a configuration snapshot, the rule cannot run more frequently than the snapshot delivery frequency. Set an execution frequency value that is equal to or greater than the value of the snapshot delivery frequency, which is a property the AWS::Config::DeliveryChannel resource.

Required: No

Type: String

Update requires: No interruption

Scope

Defines which AWS resources will trigger an evaluation when their configurations change. The scope can include one or more resource types, a combination of a tag key and value, or a combination of one resource type and one resource ID. Specify a scope to constrain the resources that are evaluated. If you don't specify a scope, the rule evaluates all resources in the recording group.

Required: No

Type: AWS Config ConfigRule Scope

Update requires: No interruption

Source

Specifies the rule owner, the rule identifier, and the events that cause the function to evaluate your AWS resources.

Required: Yes

Type: AWS Config ConfigRule Source

Update requires: No interruption

Return Values

Ref

When you pass the logical ID of an AWS::Config::ConfigRule resource to the intrinsic Ref function, the function returns the rule name, such as mystack-MyConfigRule-12ABCFPXHV4OV.

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

Fn::GetAtt

Fn::GetAtt returns a value for a specified attribute of this type. The following are the available attributes and sample return values.

Arn: The Amazon Resource Name (ARN) of the AWS Config rule, such as arn:aws:config:us-east-1:123456789012:config-rule/config-rule-a1bzhi.
ConfigRuleId: The ID of the AWS Config rule, such as config-rule-a1bzhi.
Compliance.Type: The compliance status of an AWS Config rule, such as COMPLIANT or NON_COMPLIANT.

For more information about using Fn::GetAtt, see Fn::GetAtt.

Examples

The following example uses an AWS managed rule that checks whether EC2 volumes resource types have a CostCenter tag.

JSON


"ConfigRuleForVolumeTags": {
  "Type": "AWS::Config::ConfigRule",
  "Properties": {
    "InputParameters": {"tag1Key": "CostCenter"},
    "Scope": {
      "ComplianceResourceTypes": ["AWS::EC2::Volume"]
    },
    "Source": {
      "Owner": "AWS",
      "SourceIdentifier": "REQUIRED_TAGS"
    }
  }
}

YAML


ConfigRuleForVolumeTags: 
  Type: AWS::Config::ConfigRule
  Properties: 
    InputParameters: 
      tag1Key: CostCenter
    Scope: 
      ComplianceResourceTypes: 
        - "AWS::EC2::Volume"
    Source: 
      Owner: AWS
      SourceIdentifier: "REQUIRED_TAGS"

Rule Using Lambda Function

The following example creates a custom configuration rule that uses a Lambda function. The function checks whether an EC2 volume has the AutoEnableIO property set to true. Note that the configuration rule has a dependency on the Lambda policy so that the rule calls the function only after it's permitted to do so.

JSON


"ConfigPermissionToCallLambda": {
  "Type": "AWS::Lambda::Permission",
  "Properties": {
    "FunctionName": {"Fn::GetAtt": ["VolumeAutoEnableIOComplianceCheck", "Arn"]},
    "Action": "lambda:InvokeFunction",
    "Principal": "config.amazonaws.com"
  }
},
"VolumeAutoEnableIOComplianceCheck": {
  "Type": "AWS::Lambda::Function",
  "Properties": {
    "Code": {
      "ZipFile":  {"Fn::Join": ["\n", [
        "var aws  = require('aws-sdk');",
        "var config = new aws.ConfigService();",
        "var ec2 = new aws.EC2();",

        "exports.handler = function(event, context) {",
        "    compliance = evaluateCompliance(event, function(compliance, event) {",
        "        var configurationItem = JSON.parse(event.invokingEvent).configurationItem;",

        "        var putEvaluationsRequest = {",
        "            Evaluations: [{",
        "                ComplianceResourceType: configurationItem.resourceType,",
        "                ComplianceResourceId: configurationItem.resourceId,",
        "                ComplianceType: compliance,",
        "                OrderingTimestamp: configurationItem.configurationItemCaptureTime",
        "            }],",
        "            ResultToken: event.resultToken",
        "        };",

        "        config.putEvaluations(putEvaluationsRequest, function(err, data) {",
        "            if (err) context.fail(err);",
        "            else context.succeed(data);",
        "        });",
        "    });",
        "};",

        "function evaluateCompliance(event, doReturn) {",
        "    var configurationItem = JSON.parse(event.invokingEvent).configurationItem;",
        "    var status = configurationItem.configurationItemStatus;",
        "    if (configurationItem.resourceType !== 'AWS::EC2::Volume' || event.eventLeftScope || (status !== 'OK' && status !== 'ResourceDiscovered'))",
        "        doReturn('NOT_APPLICABLE', event);",
        "    else ec2.describeVolumeAttribute({VolumeId: configurationItem.resourceId, Attribute: 'autoEnableIO'}, function(err, data) {",
        "        if (err) context.fail(err);",
        "        else if (data.AutoEnableIO.Value) doReturn('COMPLIANT', event);",
        "        else doReturn('NON_COMPLIANT', event);",
        "    });",
        "}"
      ]]}
    },
    "Handler": "index.handler",
    "Runtime": "nodejs4.3",
    "Timeout": "30",
    "Role": {"Fn::GetAtt": ["LambdaExecutionRole", "Arn"]}
  }
},
"ConfigRuleForVolumeAutoEnableIO": {
  "Type": "AWS::Config::ConfigRule",
  "Properties": {
    "ConfigRuleName": "ConfigRuleForVolumeAutoEnableIO",
    "Scope": {
      "ComplianceResourceId": {"Ref": "Ec2Volume"},
      "ComplianceResourceTypes": ["AWS::EC2::Volume"]
    },
    "Source": {
      "Owner": "CUSTOM_LAMBDA",
      "SourceDetails": [{
          "EventSource": "aws.config",
          "MessageType": "ConfigurationItemChangeNotification"
      }],
      "SourceIdentifier": {"Fn::GetAtt": ["VolumeAutoEnableIOComplianceCheck", "Arn"]}
    }
  },
  "DependsOn": "ConfigPermissionToCallLambda"
}

YAML


ConfigPermissionToCallLambda: 
  Type: AWS::Lambda::Permission
  Properties: 
    FunctionName: 
      Fn::GetAtt: 
        - VolumeAutoEnableIOComplianceCheck
        - Arn
    Action: "lambda:InvokeFunction"
    Principal: "config.amazonaws.com"
VolumeAutoEnableIOComplianceCheck: 
  Type: AWS::Lambda::Function
  Properties: 
    Code: 
      ZipFile: 
        !Sub |
          var aws  = require('aws-sdk');
          var config = new aws.ConfigService();
          var ec2 = new aws.EC2();
          exports.handler = function(event, context) {
              compliance = evaluateCompliance(event, function(compliance, event) {
                    var configurationItem = JSON.parse(event.invokingEvent).configurationItem;
                    var putEvaluationsRequest = {
                        Evaluations: [{
                            ComplianceResourceType: configurationItem.resourceType,
                            ComplianceResourceId: configurationItem.resourceId,
                            ComplianceType: compliance,
                            OrderingTimestamp: configurationItem.configurationItemCaptureTime
                        }],
                        ResultToken: event.resultToken
                    };
                    config.putEvaluations(putEvaluationsRequest, function(err, data) {
                        if (err) context.fail(err);
                        else context.succeed(data);
                    });
                });
            };
            function evaluateCompliance(event, doReturn) {
                var configurationItem = JSON.parse(event.invokingEvent).configurationItem;
                var status = configurationItem.configurationItemStatus;
                if (configurationItem.resourceType !== 'AWS::EC2::Volume' || event.eventLeftScope || (status !== 'OK' && status !== 'ResourceDiscovered'))
                    doReturn('NOT_APPLICABLE', event);
                else ec2.describeVolumeAttribute({VolumeId: configurationItem.resourceId, Attribute: 'autoEnableIO'}, function(err, data) {
                    if (err) context.fail(err);
                    else if (data.AutoEnableIO.Value) doReturn('COMPLIANT', event);
                    else doReturn('NON_COMPLIANT', event);
                });
            }
    Handler: "index.handler"
    Runtime: nodejs4.3
    Timeout: 30
    Role: 
      Fn::GetAtt: 
        - LambdaExecutionRole
        - Arn
ConfigRuleForVolumeAutoEnableIO: 
  Type: AWS::Config::ConfigRule
  Properties: 
    ConfigRuleName: ConfigRuleForVolumeAutoEnableIO
    Scope: 
      ComplianceResourceId: 
        Ref: Ec2Volume
      ComplianceResourceTypes: 
        - "AWS::EC2::Volume"
    Source: 
      Owner: "CUSTOM_LAMBDA"
      SourceDetails: 
        - 
          EventSource: "aws.config"
          MessageType: "ConfigurationItemChangeNotification"
      SourceIdentifier: 
        Fn::GetAtt: 
          - VolumeAutoEnableIOComplianceCheck
          - Arn
  DependsOn: ConfigPermissionToCallLambda

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