# AWS::VpcLattice::Listener

Creates a listener for a service. Before you start using your Amazon VPC Lattice service, you must add one or more listeners. A listener is a process that checks for connection requests to your services.

## Syntax

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

### JSON

<pre>
{
    "Type" : "AWS::VpcLattice::Listener",
    "Properties" : {
        "<a href="#defaultaction" title="DefaultAction">DefaultAction</a>" : <i><a href="defaultaction.md">DefaultAction</a></i>,
        "<a href="#name" title="Name">Name</a>" : <i>String</i>,
        "<a href="#port" title="Port">Port</a>" : <i>Integer</i>,
        "<a href="#protocol" title="Protocol">Protocol</a>" : <i>String</i>,
        "<a href="#serviceidentifier" title="ServiceIdentifier">ServiceIdentifier</a>" : <i>String</i>,
        "<a href="#tags" title="Tags">Tags</a>" : <i>[ <a href="tag.md">Tag</a>, ... ]</i>
    }
}
</pre>

### YAML

<pre>
Type: AWS::VpcLattice::Listener
Properties:
    <a href="#defaultaction" title="DefaultAction">DefaultAction</a>: <i><a href="defaultaction.md">DefaultAction</a></i>
    <a href="#name" title="Name">Name</a>: <i>String</i>
    <a href="#port" title="Port">Port</a>: <i>Integer</i>
    <a href="#protocol" title="Protocol">Protocol</a>: <i>String</i>
    <a href="#serviceidentifier" title="ServiceIdentifier">ServiceIdentifier</a>: <i>String</i>
    <a href="#tags" title="Tags">Tags</a>: <i>
      - <a href="tag.md">Tag</a></i>
</pre>

## Properties

#### DefaultAction

_Required_: Yes

_Type_: <a href="defaultaction.md">DefaultAction</a>

_Update requires_: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

#### Name

_Required_: No

_Type_: String

_Minimum Length_: <code>3</code>

_Maximum Length_: <code>63</code>

_Pattern_: <code>^(?!listener-)(?![-])(?!.*[-]$)(?!.*[-]{2})[a-z0-9-]+$</code>

_Update requires_: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

#### Port

_Required_: No

_Type_: Integer

_Update requires_: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

#### Protocol

_Required_: Yes

_Type_: String

_Allowed Values_: <code>HTTP</code> | <code>HTTPS</code>

_Update requires_: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

#### ServiceIdentifier

_Required_: No

_Type_: String

_Minimum Length_: <code>21</code>

_Maximum Length_: <code>2048</code>

_Pattern_: <code>^((svc-[0-9a-z]{17})|(arn:[a-z0-9\-]+:vpc-lattice:[a-zA-Z0-9\-]+:\d{12}:service/svc-[0-9a-z]{17}))$</code>

_Update requires_: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

#### Tags

_Required_: No

_Type_: List of <a href="tag.md">Tag</a>

_Update requires_: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

## Return Values

### Ref

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

### Fn::GetAtt

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 [Fn::GetAtt](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-getatt.html).

#### Arn

Returns the <code>Arn</code> value.

#### Id

Returns the <code>Id</code> value.

#### ServiceArn

Returns the <code>ServiceArn</code> value.

#### ServiceId

Returns the <code>ServiceId</code> value.