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

# AWS::Greengrass::SubscriptionDefinition
<a name="aws-resource-greengrass-subscriptiondefinition"></a>

The `AWS::Greengrass::SubscriptionDefinition` resource represents a subscription definition for AWS IoT Greengrass. Subscription definitions are used to organize your subscription definition versions.

Subscription definitions can reference multiple subscription definition versions. All subscription definition versions must be associated with a subscription definition. Each subscription definition version can contain one or more subscriptions.

**Note**  
When you create a subscription definition, you can optionally include an initial subscription definition version. To associate a subscription definition version later, create an [https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-greengrass-subscriptiondefinitionversion.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-greengrass-subscriptiondefinitionversion.html) resource and specify the ID of this subscription definition.  
After you create the subscription definition version that contains the subscriptions you want to deploy, you must add it to your group version. For more information, see [https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-greengrass-group.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-greengrass-group.html).

## Syntax
<a name="aws-resource-greengrass-subscriptiondefinition-syntax"></a>

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

### JSON
<a name="aws-resource-greengrass-subscriptiondefinition-syntax.json"></a>

```
{
  "Type" : "AWS::Greengrass::SubscriptionDefinition",
  "Properties" : {
      "[InitialVersion](#cfn-greengrass-subscriptiondefinition-initialversion)" : SubscriptionDefinitionVersion,
      "[Name](#cfn-greengrass-subscriptiondefinition-name)" : String,
      "[Tags](#cfn-greengrass-subscriptiondefinition-tags)" : [ [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-properties-resource-tags.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-properties-resource-tags.html), ... ]
    }
}
```

### YAML
<a name="aws-resource-greengrass-subscriptiondefinition-syntax.yaml"></a>

```
Type: AWS::Greengrass::SubscriptionDefinition
Properties:
  [InitialVersion](#cfn-greengrass-subscriptiondefinition-initialversion): 
    SubscriptionDefinitionVersion
  [Name](#cfn-greengrass-subscriptiondefinition-name): String
  [Tags](#cfn-greengrass-subscriptiondefinition-tags): 
    - [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-properties-resource-tags.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-properties-resource-tags.html)
```

## Properties
<a name="aws-resource-greengrass-subscriptiondefinition-properties"></a>

`InitialVersion`  <a name="cfn-greengrass-subscriptiondefinition-initialversion"></a>
The subscription definition version to include when the subscription definition is created. A subscription definition version contains a list of [https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-greengrass-subscriptiondefinition-subscription.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-greengrass-subscriptiondefinition-subscription.html) property types.  
To associate a subscription definition version after the subscription definition is created, create an [https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-greengrass-subscriptiondefinitionversion.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-greengrass-subscriptiondefinitionversion.html) resource and specify the ID of this subscription definition.
*Required*: No  
*Type*: [SubscriptionDefinitionVersion](aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion.md)  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`Name`  <a name="cfn-greengrass-subscriptiondefinition-name"></a>
The name of the subscription definition.  
*Required*: Yes  
*Type*: String  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`Tags`  <a name="cfn-greengrass-subscriptiondefinition-tags"></a>
Application-specific metadata to attach to the subscription definition. You can use tags in IAM policies to control access to AWS IoT Greengrass resources. You can also use tags to categorize your resources. For more information, see [Tagging Your AWS IoT Greengrass Resources](https://docs.aws.amazon.com/greengrass/v1/developerguide/tagging.html) in the * AWS IoT Greengrass Version 1 Developer Guide *.  
This `Json` property type is processed as a map of key-value pairs. It uses the following format, which is different from most `Tags` implementations in CloudFormation templates.  

```
"Tags": {
    "KeyName0": "value",
    "KeyName1": "value",
    "KeyName2": "value"
}
```
*Required*: No  
*Type*: Array of [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-properties-resource-tags.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-properties-resource-tags.html)  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

## Return values
<a name="aws-resource-greengrass-subscriptiondefinition-return-values"></a>

### Ref
<a name="aws-resource-greengrass-subscriptiondefinition-return-values-ref"></a>

When you pass the logical ID of this resource to the intrinsic `Ref` function, `Ref` returns the ID of the subscription definition, such as `1234a5b6-78cd-901e-2fgh-3i45j6k178l9`. 

For more information about using the `Ref` function, see [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-ref.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-ref.html).

### Fn::GetAtt
<a name="aws-resource-greengrass-subscriptiondefinition-return-values-fn--getatt"></a>

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

For more information about using the `Fn::GetAtt` intrinsic function, see [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-getatt.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-getatt.html).

#### 
<a name="aws-resource-greengrass-subscriptiondefinition-return-values-fn--getatt-fn--getatt"></a>

`Arn`  <a name="Arn-fn::getatt"></a>
The Amazon Resource Name (ARN) of the `SubscriptionDefinition`, such as `arn:aws:greengrass:us-east-1:123456789012:/greengrass/definition/subscriptions/1234a5b6-78cd-901e-2fgh-3i45j6k178l9`. 

`Id`  <a name="Id-fn::getatt"></a>
The ID of the `SubscriptionDefinition`, such as `1234a5b6-78cd-901e-2fgh-3i45j6k178l9`. 

`LatestVersionArn`  <a name="LatestVersionArn-fn::getatt"></a>
The ARN of the last `SubscriptionDefinitionVersion` that was added to the `SubscriptionDefinition`, such as `arn:aws:greengrass:us-east-1:123456789012:/greengrass/definition/subscriptions/1234a5b6-78cd-901e-2fgh-3i45j6k178l9/versions/9876ac30-4bdb-4f9d-95af-b5fdb66be1a2`. 

`Name`  <a name="Name-fn::getatt"></a>
The name of the `SubscriptionDefinition`, such as `MySubscriptionDefinition`. 

## Examples
<a name="aws-resource-greengrass-subscriptiondefinition--examples"></a>



### Subscription Definition Snippet
<a name="aws-resource-greengrass-subscriptiondefinition--examples--Subscription_Definition_Snippet"></a>

The following snippet defines a subscription definition subscription with an initial version that contains a subscription. In this example, the subscription source is an existing device in the group. The target is a function in the group that was created in another stack and is referenced using the `ImportValue` function.

For an example of a complete template, see the [https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-subscription-greengrass-group.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-subscription-greengrass-group.html) subscription.

#### JSON
<a name="aws-resource-greengrass-subscriptiondefinition--examples--Subscription_Definition_Snippet--json"></a>

```
"TestSubscriptionDefinition": {
    "Type": "AWS::Greengrass::SubscriptionDefinition",
    "Properties": {
        "Name": "DemoTestSubscriptionDefinition",
        "InitialVersion": {
            "Subscriptions": [
                {
                    "Id": "TestSubscription1",
                    "Source": {
                        "Fn::Join": [
                            ":",
                            [
                                "arn:aws:iot",
                                {
                                    "Ref": "AWS::Region"
                                },
                                {
                                    "Ref": "AWS::AccountId"
                                },
                                "thing/TestDevice1"
                            ]
                        ]
                    },
                    "Subject": "some/topic",
                    "Target": {
                        "Fn::ImportValue": "TestCanaryLambdaVersionArn"
                    }
                }
            ]
        }
    }
}
```

#### YAML
<a name="aws-resource-greengrass-subscriptiondefinition--examples--Subscription_Definition_Snippet--yaml"></a>

```
TestSubscriptionDefinition:
  Type: 'AWS::Greengrass::SubscriptionDefinition'
  Properties:
    Name: DemoTestSubscriptionDefinition
    InitialVersion:
      Subscriptions:
        - Id: TestSubscription1
          Source: !Join 
            - ':'
            - - 'arn:aws:iot'
              - !Ref 'AWS::Region'
              - !Ref 'AWS::AccountId'
              - thing/TestDevice1
          Subject: some/topic
          Target: !ImportValue TestCanaryLambdaVersionArn
```

## See also
<a name="aws-resource-greengrass-subscriptiondefinition--seealso"></a>
+ [CreateSubscriptionDefinition](https://docs.aws.amazon.com/greengrass/v1/apireference/createsubscriptiondefinition-post.html) in the * AWS IoT Greengrass Version 1 API Reference *
+  [AWS IoT Greengrass Version 1 Developer Guide](https://docs.aws.amazon.com/greengrass/v1/developerguide/) 

# AWS::Greengrass::SubscriptionDefinition Subscription
<a name="aws-properties-greengrass-subscriptiondefinition-subscription"></a>

<a name="aws-properties-greengrass-subscriptiondefinition-subscription-description"></a>Subscriptions define how MQTT messages can be exchanged between devices, functions, and connectors in the group, and with AWS IoT or the local shadow service. A subscription defines a message source, message target, and a topic (or subject) that's used to route messages from the source to the target. A subscription defines the message flow in one direction, from the source to the target. For two-way communication, you must set up two subscriptions, one for each direction.

<a name="aws-properties-greengrass-subscriptiondefinition-subscription-inheritance"></a> In an CloudFormation template, the `Subscriptions` property of the [https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion.html) property type contains a list of `Subscription` property types.

## Syntax
<a name="aws-properties-greengrass-subscriptiondefinition-subscription-syntax"></a>

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

### JSON
<a name="aws-properties-greengrass-subscriptiondefinition-subscription-syntax.json"></a>

```
{
  "[Id](#cfn-greengrass-subscriptiondefinition-subscription-id)" : String,
  "[Source](#cfn-greengrass-subscriptiondefinition-subscription-source)" : String,
  "[Subject](#cfn-greengrass-subscriptiondefinition-subscription-subject)" : String,
  "[Target](#cfn-greengrass-subscriptiondefinition-subscription-target)" : String
}
```

### YAML
<a name="aws-properties-greengrass-subscriptiondefinition-subscription-syntax.yaml"></a>

```
  [Id](#cfn-greengrass-subscriptiondefinition-subscription-id): String
  [Source](#cfn-greengrass-subscriptiondefinition-subscription-source): String
  [Subject](#cfn-greengrass-subscriptiondefinition-subscription-subject): String
  [Target](#cfn-greengrass-subscriptiondefinition-subscription-target): String
```

## Properties
<a name="aws-properties-greengrass-subscriptiondefinition-subscription-properties"></a>

`Id`  <a name="cfn-greengrass-subscriptiondefinition-subscription-id"></a>
A descriptive or arbitrary ID for the subscription. This value must be unique within the subscription definition version. Maximum length is 128 characters with pattern `[a-zA-Z0-9:_-]+`.  
*Required*: Yes  
*Type*: String  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`Source`  <a name="cfn-greengrass-subscriptiondefinition-subscription-source"></a>
The originator of the message. The value can be a thing ARN, the ARN of a Lambda function alias (recommended) or version, a connector ARN, `cloud` (which represents the AWS IoT cloud), or `GGShadowService`.  
*Required*: Yes  
*Type*: String  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`Subject`  <a name="cfn-greengrass-subscriptiondefinition-subscription-subject"></a>
The MQTT topic used to route the message.  
*Required*: Yes  
*Type*: String  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`Target`  <a name="cfn-greengrass-subscriptiondefinition-subscription-target"></a>
The destination of the message. The value can be a thing ARN, the ARN of a Lambda function alias (recommended) or version, a connector ARN, `cloud` (which represents the AWS IoT cloud), or `GGShadowService`.  
*Required*: Yes  
*Type*: String  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

## See also
<a name="aws-properties-greengrass-subscriptiondefinition-subscription--seealso"></a>
+ [Subscription](https://docs.aws.amazon.com/greengrass/v1/apireference/definitions-subscription.html) in the * AWS IoT Greengrass Version 1 API Reference *
+  [AWS IoT Greengrass Version 1 Developer Guide](https://docs.aws.amazon.com/greengrass/v1/developerguide/) 

# AWS::Greengrass::SubscriptionDefinition SubscriptionDefinitionVersion
<a name="aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion"></a>

<a name="aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion-description"></a> A subscription definition version contains a list of [subscriptions](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-greengrass-subscriptiondefinition-subscription.html).

**Note**  
After you create a subscription definition version that contains the subscriptions you want to deploy, you must add it to your group version. For more information, see [https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-greengrass-group.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-greengrass-group.html).

<a name="aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion-inheritance"></a> In an CloudFormation template, `SubscriptionDefinitionVersion` is the property type of the `InitialVersion` property in the [https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-greengrass-subscriptiondefinition.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-greengrass-subscriptiondefinition.html) resource.

## Syntax
<a name="aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion-syntax"></a>

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

### JSON
<a name="aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion-syntax.json"></a>

```
{
  "[Subscriptions](#cfn-greengrass-subscriptiondefinition-subscriptiondefinitionversion-subscriptions)" : [ Subscription, ... ]
}
```

### YAML
<a name="aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion-syntax.yaml"></a>

```
  [Subscriptions](#cfn-greengrass-subscriptiondefinition-subscriptiondefinitionversion-subscriptions): 
    - Subscription
```

## Properties
<a name="aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion-properties"></a>

`Subscriptions`  <a name="cfn-greengrass-subscriptiondefinition-subscriptiondefinitionversion-subscriptions"></a>
The subscriptions in this version.  
*Required*: Yes  
*Type*: Array of [Subscription](aws-properties-greengrass-subscriptiondefinition-subscription.md)  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

## See also
<a name="aws-properties-greengrass-subscriptiondefinition-subscriptiondefinitionversion--seealso"></a>
+ [SubscriptionDefinitionVersion](https://docs.aws.amazon.com/greengrass/v1/apireference/definitions-subscriptiondefinitionversion.html) in the * AWS IoT Greengrass Version 1 API Reference *
+  [AWS IoT Greengrass Version 1 Developer Guide](https://docs.aws.amazon.com/greengrass/v1/developerguide/)