This is the new *Amazon CloudFormation Template Reference Guide*. Please update your bookmarks and links. For help getting started with CloudFormation, see the [Amazon CloudFormation User Guide](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/Welcome.html).

# AWS::Config::ConfigRule SourceDetail
<a name="aws-properties-config-configrule-sourcedetail"></a>

Provides the source and the message types that trigger Amazon Config to evaluate your Amazon resources against a rule. It also provides the frequency with which you want Amazon Config to run evaluations for the rule if the trigger type is periodic. You can specify the parameter values for `SourceDetail` only for custom rules. 

## Syntax
<a name="aws-properties-config-configrule-sourcedetail-syntax"></a>

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

### JSON
<a name="aws-properties-config-configrule-sourcedetail-syntax.json"></a>

```
{
  "[EventSource](#cfn-config-configrule-sourcedetail-eventsource)" : {{String}},
  "[MaximumExecutionFrequency](#cfn-config-configrule-sourcedetail-maximumexecutionfrequency)" : {{String}},
  "[MessageType](#cfn-config-configrule-sourcedetail-messagetype)" : {{String}}
}
```

### YAML
<a name="aws-properties-config-configrule-sourcedetail-syntax.yaml"></a>

```
  [EventSource](#cfn-config-configrule-sourcedetail-eventsource): {{String}}
  [MaximumExecutionFrequency](#cfn-config-configrule-sourcedetail-maximumexecutionfrequency): {{String}}
  [MessageType](#cfn-config-configrule-sourcedetail-messagetype): {{String}}
```

## Properties
<a name="aws-properties-config-configrule-sourcedetail-properties"></a>

`EventSource`  <a name="cfn-config-configrule-sourcedetail-eventsource"></a>
The source of the event, such as an Amazon service, that triggers Amazon Config to evaluate your Amazon resources.  
*Required*: Yes  
*Type*: String  
*Allowed values*: `aws.config`  
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`MaximumExecutionFrequency`  <a name="cfn-config-configrule-sourcedetail-maximumexecutionfrequency"></a>
The frequency at which you want Amazon Config to run evaluations for a custom rule with a periodic trigger. If you specify a value for `MaximumExecutionFrequency`, then `MessageType` must use the `ScheduledNotification` value.  
By default, rules with a periodic trigger are evaluated every 24 hours. To change the frequency, specify a valid value for the `MaximumExecutionFrequency` parameter.  
Based on the valid value you choose, Amazon Config runs evaluations once for each valid value. For example, if you choose `Three_Hours`, Amazon Config runs evaluations once every three hours. In this case, `Three_Hours` is the frequency of this rule. 
*Required*: No  
*Type*: String  
*Allowed values*: `One_Hour | Three_Hours | Six_Hours | Twelve_Hours | TwentyFour_Hours`  
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`MessageType`  <a name="cfn-config-configrule-sourcedetail-messagetype"></a>
The type of notification that triggers Amazon Config to run an evaluation for a rule. You can specify the following notification types:  
+ `ConfigurationItemChangeNotification` - Triggers an evaluation when Amazon Config delivers a configuration item as a result of a resource change.
+ `OversizedConfigurationItemChangeNotification` - Triggers an evaluation when Amazon Config delivers an oversized configuration item. Amazon Config may generate this notification type when a resource changes and the notification exceeds the maximum size allowed by Amazon SNS.
+ `ScheduledNotification` - Triggers a periodic evaluation at the frequency specified for `MaximumExecutionFrequency`.
+ `ConfigurationSnapshotDeliveryCompleted` - Triggers a periodic evaluation when Amazon Config delivers a configuration snapshot.
If you want your custom rule to be triggered by configuration changes, specify two SourceDetail objects, one for `ConfigurationItemChangeNotification` and one for `OversizedConfigurationItemChangeNotification`.  
*Required*: Yes  
*Type*: String  
*Allowed values*: `ConfigurationItemChangeNotification | ConfigurationSnapshotDeliveryCompleted | ScheduledNotification | OversizedConfigurationItemChangeNotification`  
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)