feat(cdk): enables customization of the API domain

While the Next.js rewrite support works nicely, it increases the total
cost of the deployment since the server API will be charged while the
real backend does its work. This gets worse when the backend is also
deployed as a lambda function on the same account, as they will consume
two concurrent execution quotas.

Author: fabiob

Diff for: lib/cdk/app.ts

@@ -38,6 +38,7 @@ new NextStandaloneStack(app, process.env.STACK_NAME, {
 	imageLambdaMemory: process.env.LAMBDA_MEMORY ? Number(process.env.IMAGE_LAMBDA_MEMORY) : IMAGE_LAMBDA_DEFAULT_MEMORY,
 	hostedZone: process.env.HOSTED_ZONE ?? undefined,
 	dnsPrefix: process.env.DNS_PREFIX ?? undefined,
+	customApiDomain: process.env.CUSTOM_API_DOMAIN ?? undefined,
 	env: {
 		account: process.env.CDK_DEFAULT_ACCOUNT,
 		region: process.env.CDK_DEFAULT_REGION,

Diff for: lib/cdk/stack.ts

@@ -2,6 +2,7 @@ import { HttpApi } from '@aws-cdk/aws-apigatewayv2-alpha'
 import { App, Stack } from 'aws-cdk-lib'
 import { ICertificate } from 'aws-cdk-lib/aws-certificatemanager'
 import { IDistribution } from 'aws-cdk-lib/aws-cloudfront'
+import { HttpOrigin } from 'aws-cdk-lib/aws-cloudfront-origins'
 import { Function } from 'aws-cdk-lib/aws-lambda'
 import { HostedZone, IHostedZone } from 'aws-cdk-lib/aws-route53'
 import { Bucket } from 'aws-cdk-lib/aws-s3'
@@ -76,6 +77,7 @@ export class NextStandaloneStack extends Stack {
 			serverBasePath: config.apigwServerPath,
 			domainName: config.dnsPrefix ? `${config.dnsPrefix}.${config.hostedZone}` : config.hostedZone,
 			certificate: this.cfnCertificate,
+			customApiOrigin: config.customApiDomain ? new HttpOrigin(config.customApiDomain) : undefined,
 		})
 
 		this.uploadStaticAssets({

Diff for: lib/cdk/types.ts

@@ -17,4 +17,5 @@ export interface CustomStackProps extends StackProps {
 	imageLambdaMemory?: number
 	hostedZone?: string
 	dnsPrefix?: string
+	customApiDomain?: string
 }

Diff for: lib/cdk/utils/cfnDistro.ts

@@ -8,6 +8,7 @@ import {
 	CachePolicy,
 	CacheQueryStringBehavior,
 	Distribution,
+	IOrigin,
 	PriceClass,
 	ViewerProtocolPolicy,
 } from 'aws-cdk-lib/aws-cloudfront'
@@ -21,9 +22,10 @@ export interface SetupCfnDistroProps {
 	imageBasePath: string
 	serverBasePath: string
 	assetsBucket: Bucket
+	customApiOrigin?: IOrigin
 }
 
-export const setupCfnDistro = (scope: Stack, { apiGateway, imageBasePath, serverBasePath, assetsBucket, domainName, certificate }: SetupCfnDistroProps) => {
+export const setupCfnDistro = (scope: Stack, { apiGateway, imageBasePath, serverBasePath, assetsBucket, domainName, certificate, customApiOrigin }: SetupCfnDistroProps) => {
 	const apiGwDomainName = `${apiGateway.apiId}.execute-api.${scope.region}.amazonaws.com`
 
 	const serverOrigin = new HttpOrigin(apiGwDomainName, { originPath: serverBasePath })
@@ -80,7 +82,7 @@ export const setupCfnDistro = (scope: Stack, { apiGateway, imageBasePath, server
 		additionalBehaviors: {
 			'/api*': {
 				...defaultOptions,
-				origin: serverOrigin,
+				origin: customApiOrigin ?? serverOrigin,
 				allowedMethods: AllowedMethods.ALLOW_ALL,
 				cachePolicy: apiCachePolicy,
 			},