Creating a Gateway Response

A gateway response is displayed if APIG fails to process an API request. APIG provides a set of default responses and also allows you to create responses with custom status codes and content. The response content must be in JSON format.

For example, the content of a default gateway response is as follows:

{"error_code": "$context.error.code", "error_msg": "$context.error.message", "request_id": "$context.requestId"}

You can add a response with the following content:

{"errorcode": "$context.error.code", "errormsg": "$context.error.message", "requestid": "$context.requestId","apiId":"$context.apiId"}

You can add more fields to or delete existing fields from the JSON body.

You can create a maximum of four gateway responses for each group.
The type of a default or custom response cannot be modified, but the status code and content of the response can.
The type of a gateway response cannot be changed. For details, see Response Types.
Gateway responses can contain the API gateway context variables (starting with $context). For details, see Context Variables.

Procedure

Go to the APIG console.

Select a dedicated gateway at the top of the navigation pane.

Choose API Management > API Groups.

Click a group name.
Click the Group Information tab.
In the Gateway Responses area, create or modify gateway responses.

To cancel modifications to a default response, click Restore Defaults in the upper right.

Response Types

The following table lists the response types supported by APIG. You can define status codes to meet your service requirements.

**Table 1** Error response types supported by APIG
Response Name	Default Status Code	Description
Access Denied	403	Access denied. For example, the access control policy is triggered or an attack is detected.
Authorizer Configuration Error	500	A custom authorizer error has occurred. For example, communication failed or an error response was returned.
Authorizer Failed	500	The custom authorization failed.
Incorrect Identity Source	401	The identity source of the custom authorizer is missing or invalid.
Third-Party Configuration Error	500	A third-party authorizer error has occurred. For example, communication failed or an error response was returned.
Third-Party Authorizer Failure	401	The third-party authorizer returns an authentication failure.
Incorrect Third-Party Identity Source	401	The identity source of the third-party authorizer is missing.
Authentication Failure	401	IAM or app authentication failed.
Identity Source Not Found	401	No identity source has been specified.
Backend Timeout	504	Communication with the backend service timed out.
Backend Unavailable	502	The backend service is unavailable due to communication error.
Default 4XX	-	Another 4XX error occurred.
Default 5XX	-	Another 5XX error occurred.
No API Found	404	No API is found.
Incorrect Request Parameters	400	The request parameters are incorrect or the HTTP method is not supported.
Request Throttled	429	The request was rejected due to request throttling.
Unauthorized Credential	401	The credential you are using has not been authorized to call the API.

Context Variables

**Table 2** Variables that can be used in response message body
Variable	Description
$context.apiId	API ID.
$context.appId	ID of the credential that calls the API.
$context.requestId	Request ID generated when the API is called.
$context.stage	Deployment environment in which the API is called.
$context.sourceIp	Source IP address of the API caller.
$context.authorizer.frontend.property	Values of the specified attribute–value pairs mapped to the context in the frontend custom authorizer response
$context.authorizer.backend.property	Values of the specified attribute–value pairs mapped to the context in the backend custom authorizer response
$context.error.message	Error message.
$context.error.code	Error code.
$context.error.type	Error type.