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::AppSync::ChannelNamespace
<a name="aws-resource-appsync-channelnamespace"></a>

The `AWS::AppSync::ChannelNamespace` resource creates a channel namespace associated with an `Api`. The `ChannelNamespace` contains the definitions for code handlers for the `Api`.

## Syntax
<a name="aws-resource-appsync-channelnamespace-syntax"></a>

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

### JSON
<a name="aws-resource-appsync-channelnamespace-syntax.json"></a>

```
{
  "Type" : "AWS::AppSync::ChannelNamespace",
  "Properties" : {
      "[ApiId](#cfn-appsync-channelnamespace-apiid)" : String,
      "[CodeHandlers](#cfn-appsync-channelnamespace-codehandlers)" : String,
      "[CodeS3Location](#cfn-appsync-channelnamespace-codes3location)" : String,
      "[HandlerConfigs](#cfn-appsync-channelnamespace-handlerconfigs)" : HandlerConfigs,
      "[Name](#cfn-appsync-channelnamespace-name)" : String,
      "[PublishAuthModes](#cfn-appsync-channelnamespace-publishauthmodes)" : [ AuthMode, ... ],
      "[SubscribeAuthModes](#cfn-appsync-channelnamespace-subscribeauthmodes)" : [ AuthMode, ... ],
      "[Tags](#cfn-appsync-channelnamespace-tags)" : [ Tag, ... ]
    }
}
```

### YAML
<a name="aws-resource-appsync-channelnamespace-syntax.yaml"></a>

```
Type: AWS::AppSync::ChannelNamespace
Properties:
  [ApiId](#cfn-appsync-channelnamespace-apiid): String
  [CodeHandlers](#cfn-appsync-channelnamespace-codehandlers): String
  [CodeS3Location](#cfn-appsync-channelnamespace-codes3location): String
  [HandlerConfigs](#cfn-appsync-channelnamespace-handlerconfigs): 
    HandlerConfigs
  [Name](#cfn-appsync-channelnamespace-name): String
  [PublishAuthModes](#cfn-appsync-channelnamespace-publishauthmodes): 
    - AuthMode
  [SubscribeAuthModes](#cfn-appsync-channelnamespace-subscribeauthmodes): 
    - AuthMode
  [Tags](#cfn-appsync-channelnamespace-tags): 
    - Tag
```

## Properties
<a name="aws-resource-appsync-channelnamespace-properties"></a>

`ApiId`  <a name="cfn-appsync-channelnamespace-apiid"></a>
The `Api` ID.  
*Required*: Yes  
*Type*: String  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`CodeHandlers`  <a name="cfn-appsync-channelnamespace-codehandlers"></a>
The event handler functions that run custom business logic to process published events and subscribe requests.  
*Required*: No  
*Type*: String  
*Minimum*: `1`  
*Maximum*: `32768`  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`CodeS3Location`  <a name="cfn-appsync-channelnamespace-codes3location"></a>
The Amazon S3 endpoint where the code is located.  
*Required*: No  
*Type*: String  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`HandlerConfigs`  <a name="cfn-appsync-channelnamespace-handlerconfigs"></a>
The configuration for the `OnPublish` and `OnSubscribe` handlers.  
*Required*: No  
*Type*: [HandlerConfigs](aws-properties-appsync-channelnamespace-handlerconfigs.md)  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`Name`  <a name="cfn-appsync-channelnamespace-name"></a>
The name of the channel namespace. This name must be unique within the `Api`.  
*Required*: Yes  
*Type*: String  
*Pattern*: `([A-Za-z0-9](?:[A-Za-z0-9\-]{0,48}[A-Za-z0-9])?)`  
*Minimum*: `1`  
*Maximum*: `50`  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`PublishAuthModes`  <a name="cfn-appsync-channelnamespace-publishauthmodes"></a>
The authorization mode to use for publishing messages on the channel namespace. This configuration overrides the default `Api`authorization configuration.  
*Required*: No  
*Type*: Array of [AuthMode](aws-properties-appsync-channelnamespace-authmode.md)  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`SubscribeAuthModes`  <a name="cfn-appsync-channelnamespace-subscribeauthmodes"></a>
The authorization mode to use for subscribing to messages on the channel namespace. This configuration overrides the default `Api`authorization configuration.  
*Required*: No  
*Type*: Array of [AuthMode](aws-properties-appsync-channelnamespace-authmode.md)  
*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-appsync-channelnamespace-tags"></a>
A set of tags (key-value pairs) for this channel namespace.  
*Required*: No  
*Type*: Array of [Tag](aws-properties-appsync-channelnamespace-tag.md)  
*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-appsync-channelnamespace-return-values"></a>

### Ref
<a name="aws-resource-appsync-channelnamespace-return-values-ref"></a>

When you pass the logical ID of this resource to the intrinsic `Ref` function, `Ref` returns The Amazon Resource Name (ARN) of the channel namespace. 

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-appsync-channelnamespace-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-appsync-channelnamespace-return-values-fn--getatt-fn--getatt"></a>

`ChannelNamespaceArn`  <a name="ChannelNamespaceArn-fn::getatt"></a>
The Amazon Resource Name (ARN) of the channel namespace.