# Reference an OpenAPI specification external file with Infrastructure Composer
<a name="using-composer-external-files-examples-example1"></a>

This example uses Infrastructure Composer from the console to reference an external OpenAPI specification file that defines a API Gateway REST API.

First, create a new project from the Infrastructure Composer **home** page.

Next, activate **local sync** by selecting **Activate local sync** from the **Menu**. Create a new folder named `demo`, allow the prompt to view files, and select **Activate**. When prompted, select **Save changes**.

![\[The Infrastructure Composer Activate local sync window with a demo project folder selected and the Activate button is ready to be selected.\]](http://docs.amazonaws.cn/en_us/infrastructure-composer/latest/dg/images/aac_use_ex_11.png)


Next, drag an Amazon API Gateway card onto the canvas. Select **Details** to bring up the **Resource properties** panel.

![\[An API Gateway resource on the canvas with the Resource properties panel open.\]](http://docs.amazonaws.cn/en_us/infrastructure-composer/latest/dg/images/aac_use_ex_12.png)


From the **Resource properties** panel, configure the following and **save**.
+ Select the **Use external file for api definition** option.
+ Input `./api-spec.yaml` as the **relative path to external file**

![\[A window showing the checkbox marked under Use external file for api definition and a relative path to an external file defined.\]](http://docs.amazonaws.cn/en_us/infrastructure-composer/latest/dg/images/aac_use_ex_13.png)


This creates the following directory on our local machine:

```
demo
└── api-spec.yaml
```

Now, you can configure the external file on our local machine. Using our IDE, open the `api-spec.yaml` located in your project folder. Replace its contents with the following:

```
openapi: '3.0'
info: {}
paths:
  /:
    get:
      responses: {}
    post:
      x-amazon-apigateway-integration:
        credentials:
          Fn::GetAtt:
            - ApiQueuesendmessageRole
            - Arn
        httpMethod: POST
        type: aws
        uri:
          Fn::Sub: arn:${AWS::Partition}:apigateway:${AWS::Region}:sqs:path/${AWS::AccountId}/${Queue.QueueName}
        requestParameters:
          integration.request.header.Content-Type: '''application/x-www-form-urlencoded'''
        requestTemplates:
          application/json: Action=SendMessage&MessageBody={"data":$input.body}
        responses:
          default:
            statusCode: 200
      responses:
        '200':
          description: 200 response
```

In the Infrastructure Composer **Template** view, you can see that Infrastructure Composer has automatically updated your template to reference the external file.

![\[The Infrastructure Composer template view showing your infrastructure code configured to reference the external file.\]](http://docs.amazonaws.cn/en_us/infrastructure-composer/latest/dg/images/aac_use_ex_07.png)