refactor(apigateway): Enclose getaway response parameters within sing…

…le quotes (#22637)

Hi team,

Here is a follow up to #22633

Please let me know if this makes sense.
Thanks

----

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packages/@aws-cdk/aws-apigateway/README.md

@@ -1378,9 +1378,8 @@ api.addGatewayResponse('test-response', {
   type: apigateway.ResponseType.ACCESS_DENIED,
   statusCode: '500',
   responseHeaders: {
-    // Note that values must be enclosed within a pair of single quotes
-    'Access-Control-Allow-Origin': "'test.com'",
-    'test-key': "'test-value'",
+    'Access-Control-Allow-Origin': 'test.com',
+    'test-key': 'test-value',
   },
   templates: {
     'application/json': '{ "message": $context.error.messageString, "statusCode": "488", "type": "$context.error.responseType" }'

packages/@aws-cdk/aws-apigateway/lib/gateway-response.ts

@@ -2,6 +2,7 @@ import { IResource, Resource } from '@aws-cdk/core';
 import { Construct } from 'constructs';
 import { CfnGatewayResponse, CfnGatewayResponseProps } from './apigateway.generated';
 import { IRestApi } from './restapi';
+import { normalizeResponseParameterValue } from './util';
 
 /**
  * Represents gateway response resource.
@@ -88,7 +89,7 @@ export class GatewayResponse extends Resource implements IGatewayResponse {
 
     const responseParameters: { [key: string]: string } = {};
     for (const [header, value] of Object.entries(responseHeaders)) {
-      responseParameters[`gatewayresponse.header.${header}`] = value;
+      responseParameters[`gatewayresponse.header.${header}`] = normalizeResponseParameterValue(value) ;
     }
     return responseParameters;
   }

packages/@aws-cdk/aws-apigateway/lib/util.ts

@@ -11,6 +11,22 @@ export function validateHttpMethod(method: string, messagePrefix: string = '') {
   }
 }
 
+/**
+ * Response header values need to be enclosed in single quotes.
+ */
+export function normalizeResponseParameterValue(value: string) {
+  if (!value) {
+    return value;
+  }
+
+  // check if the value is already enclosed in single quotes
+  if (value.startsWith("'") && value.endsWith("'")) {
+    return value;
+  }
+
+  return `'${value}'`;
+}
+
 export function parseMethodOptionsPath(originalPath: string): { resourcePath: string, httpMethod: string } {
   if (!originalPath.startsWith('/')) {
     throw new Error(`Method options path must start with '/': ${originalPath}`);

packages/@aws-cdk/aws-apigateway/test/gateway-response.test.ts

@@ -45,6 +45,7 @@ describe('gateway response', () => {
       responseHeaders: {
         'Access-Control-Allow-Origin': 'test.com',
         'test-key': 'test-value',
+        'another-test': "'test-value-enclosed-within-single-quotes'",
       },
     });
 
@@ -54,8 +55,9 @@ describe('gateway response', () => {
       RestApiId: stack.resolve(api.restApiId),
       StatusCode: '500',
       ResponseParameters: {
-        'gatewayresponse.header.Access-Control-Allow-Origin': 'test.com',
-        'gatewayresponse.header.test-key': 'test-value',
+        'gatewayresponse.header.Access-Control-Allow-Origin': "'test.com'",
+        'gatewayresponse.header.test-key': "'test-value'",
+        'gatewayresponse.header.another-test': "'test-value-enclosed-within-single-quotes'",
       },
       ResponseTemplates: Match.absent(),
     });