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::Lambda::Alias
<a name="aws-resource-lambda-alias"></a>

The `AWS::Lambda::Alias` resource creates an [alias](https://docs.aws.amazon.com/lambda/latest/dg/configuration-aliases.html) for a Lambda function version. Use aliases to provide clients with a function identifier that you can update to invoke a different version.

You can also map an alias to split invocation requests between two versions. Use the `RoutingConfig` parameter to specify a second version and the percentage of invocation requests that it receives.

## Syntax
<a name="aws-resource-lambda-alias-syntax"></a>

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

### JSON
<a name="aws-resource-lambda-alias-syntax.json"></a>

```
{
  "Type" : "AWS::Lambda::Alias",
  "Properties" : {
      "[Description](#cfn-lambda-alias-description)" : String,
      "[FunctionName](#cfn-lambda-alias-functionname)" : String,
      "[FunctionVersion](#cfn-lambda-alias-functionversion)" : String,
      "[Name](#cfn-lambda-alias-name)" : String,
      "[ProvisionedConcurrencyConfig](#cfn-lambda-alias-provisionedconcurrencyconfig)" : ProvisionedConcurrencyConfiguration,
      "[RoutingConfig](#cfn-lambda-alias-routingconfig)" : AliasRoutingConfiguration
    }
}
```

### YAML
<a name="aws-resource-lambda-alias-syntax.yaml"></a>

```
Type: AWS::Lambda::Alias
Properties:
  [Description](#cfn-lambda-alias-description): String
  [FunctionName](#cfn-lambda-alias-functionname): String
  [FunctionVersion](#cfn-lambda-alias-functionversion): String
  [Name](#cfn-lambda-alias-name): String
  [ProvisionedConcurrencyConfig](#cfn-lambda-alias-provisionedconcurrencyconfig): 
    ProvisionedConcurrencyConfiguration
  [RoutingConfig](#cfn-lambda-alias-routingconfig): 
    AliasRoutingConfiguration
```

## Properties
<a name="aws-resource-lambda-alias-properties"></a>

`Description`  <a name="cfn-lambda-alias-description"></a>
A description of the alias.  
*Required*: No  
*Type*: String  
*Minimum*: `0`  
*Maximum*: `256`  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`FunctionName`  <a name="cfn-lambda-alias-functionname"></a>
The name or ARN of the Lambda function.  

**Name formats**
+ **Function name** - `MyFunction`.
+ **Function ARN** - `arn:aws:lambda:us-west-2:123456789012:function:MyFunction`.
+ **Partial ARN** - `123456789012:function:MyFunction`.
The length constraint applies only to the full ARN. If you specify only the function name, it is limited to 64 characters in length.  
*Required*: Yes  
*Type*: String  
*Pattern*: `(arn:(aws[a-zA-Z-]*)?:lambda:)?([a-z]{2}((-gov)|(-iso([a-z]?)))?-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9-_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?`  
*Minimum*: `1`  
*Maximum*: `140`  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`FunctionVersion`  <a name="cfn-lambda-alias-functionversion"></a>
The function version that the alias invokes.  
*Required*: Yes  
*Type*: String  
*Pattern*: `(\$LATEST|[0-9]+)`  
*Minimum*: `1`  
*Maximum*: `1024`  
*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-lambda-alias-name"></a>
The name of the alias.  
*Required*: Yes  
*Type*: String  
*Pattern*: `(?!^[0-9]+$)([a-zA-Z0-9-_]+)`  
*Minimum*: `1`  
*Maximum*: `128`  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`ProvisionedConcurrencyConfig`  <a name="cfn-lambda-alias-provisionedconcurrencyconfig"></a>
Specifies a [provisioned concurrency](https://docs.aws.amazon.com/lambda/latest/dg/configuration-concurrency.html) configuration for a function's alias.  
*Required*: No  
*Type*: [ProvisionedConcurrencyConfiguration](aws-properties-lambda-alias-provisionedconcurrencyconfiguration.md)  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`RoutingConfig`  <a name="cfn-lambda-alias-routingconfig"></a>
The [routing configuration](https://docs.aws.amazon.com/lambda/latest/dg/lambda-traffic-shifting-using-aliases.html) of the alias.  
*Required*: No  
*Type*: [AliasRoutingConfiguration](aws-properties-lambda-alias-aliasroutingconfiguration.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-lambda-alias-return-values"></a>

### Ref
<a name="aws-resource-lambda-alias-return-values-ref"></a>

When you pass the logical ID of this resource to the intrinsic `Ref` function, `Ref` returns the resource ARN.

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-lambda-alias-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-lambda-alias-return-values-fn--getatt-fn--getatt"></a>

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

## Examples
<a name="aws-resource-lambda-alias--examples"></a>



**Topics**
+ [Alias](#aws-resource-lambda-alias--examples--Alias)
+ [Weighted Alias](#aws-resource-lambda-alias--examples--Weighted_Alias)

### Alias
<a name="aws-resource-lambda-alias--examples--Alias"></a>

A Node.js function with a version and alias.

#### YAML
<a name="aws-resource-lambda-alias--examples--Alias--yaml"></a>

```
Resources:
  function:
    Type: AWS::Lambda::Function
    Properties:
      Handler: index.handler
      Role: arn:aws:iam::123456789012:role/lambda-role
      Code:
        ZipFile: |
          exports.handler = function(event){
              console.log(JSON.stringify(event, null, 2))
              const response = {
                  statusCode: 200,
                  body: JSON.stringify('Hello from Lambda!')
              }
              return response
          };
      Runtime: nodejs18.x
      TracingConfig:
        Mode: Active
  version:
    Type: AWS::Lambda::Version
    Properties:
      FunctionName: !Ref function
      Description: v1
  alias:
    Type: AWS::Lambda::Alias
    Properties:
      FunctionName: !Ref function
      FunctionVersion: !GetAtt version.Version
      Name: BLUE
```

### Weighted Alias
<a name="aws-resource-lambda-alias--examples--Weighted_Alias"></a>

An alias that routes requests to two versions.

#### YAML
<a name="aws-resource-lambda-alias--examples--Weighted_Alias--yaml"></a>

```
Resources:
  function:
    Type: AWS::Lambda::Function
    Properties:
      Handler: index.handler
      Role: arn:aws:iam::123456789012:role/lambda-role
      Code:
        ZipFile: |
          exports.handler = function(event){
              console.log(JSON.stringify(event, null, 2))
              const response = {
                  statusCode: 200,
                  body: JSON.stringify('Hello again from Lambda!')
              }
              return response
          }
      Runtime: nodejs18.x
      TracingConfig:
        Mode: Active
  version:
    Type: AWS::Lambda::Version
    Properties:
      FunctionName: !Ref function
      Description: v1
  newVersion:
    Type: AWS::Lambda::Version
    Properties:
      FunctionName: !Ref function
      Description: v2
  alias:
    Type: AWS::Lambda::Alias
    Properties:
      FunctionName: !Ref function
      FunctionVersion: !GetAtt newVersion.Version
      Name: BLUE
      RoutingConfig:
        AdditionalVersionWeights:
          - FunctionVersion: !GetAtt version.Version
            FunctionWeight: 0.5
```