# Updating a default event bus using Amazon CloudFormation in EventBridge
<a name="event-bus-update-default-cfn"></a>

Amazon CloudFormation enables you to configure and manage your Amazon resources across accounts and regions in a centralized and repeatable manner by treating infrastructure as code. CloudFormation does this by letting you create *templates*, which define the resources you want to provision and manage.

Because EventBridge provisions the default event bus into your account automatically, you cannot create it using a CloudFormation template, as you normally would for any resource you wanted to include in a CloudFormation stack. To include the default event bus in a CloudFormation stack, you must first *import* it into a stack. Once you have imported the default event bus into a stack, you can then update the event bus properties as desired.

To import an existing resource into a new or existing CloudFormation stack, you need the following information:
+ A unique identifier for the resource to import.

  For default event buses, the identifier is `Name` and then identifier value is `default`.
+ A template that accurately describes the current properties of the existing resource.

  The template snippet below contains an `AWS::Events::EventBus` resource that describes the current properties of a default event bus. In this example, the event bus has been configured to use a customer managed key and DLQ for encryption at rest.

  Also, the `AWS::Events::EventBus` resource that describes the default event bus you want to import should include a `DeletionPolicy` property set to `Retain`.

  ```
  {
      "AWSTemplateFormatVersion": "2010-09-09",
      "Description": "Default event bus import example",
      "Resources": {
          "defaultEventBus": {
              "Type" : "AWS::Events::EventBus",
              "DeletionPolicy": "Retain",
              "Properties" : {
                  "Name" : "default",
                  "KmsKeyIdentifier" : "{{KmsKeyArn}}",
                  "DeadLetterConfig" : {
                      "Arn" : "{{DLQ_ARN}}"
                  }
              }
          }
      }
  }
  ```

For more information, see [Bringing existing resources into CloudFormation management](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/resource-import.html) in the *CloudFormation User Guide*.