feat(url-shortener): use a Lambda function URL (#331)

Author: jogold

.eslintrc.json

@@ -123,35 +123,31 @@ export class UrlShortener extends Construct {
     });
 
     // Redirect function
-    const redirectFunction = new RedirectFunction(this, 'Redirect');
+    const redirectFunction = new RedirectFunction(this, 'Redirect', {
+      environment: {
+        BUCKET_NAME: bucket.bucketName,
+      },
+    });
     bucket.grantRead(redirectFunction);
 
     const distribution = new cloudfront.Distribution(this, 'Distribution', {
       defaultBehavior: {
-        origin: origins.S3BucketOrigin.withOriginAccessControl(bucket),
-        edgeLambdas: [
-          {
-            eventType: cloudfront.LambdaEdgeEventType.ORIGIN_REQUEST,
-            functionVersion: redirectFunction,
-          },
-        ],
+        origin: origins.FunctionUrlOrigin.withOriginAccessControl(redirectFunction.addFunctionUrl()),
       },
       certificate: props.certificate,
       domainNames: [domainName],
       httpVersion: cloudfront.HttpVersion.HTTP2_AND_3,
     });
 
     // Route53 records
-    new route53.ARecord(this, 'ARecord', {
+    const aliasProps = {
       zone: props.hostedZone,
       target: route53.RecordTarget.fromAlias(new targets.CloudFrontTarget(distribution)),
       recordName: props.recordName,
-    });
-    new route53.AaaaRecord(this, 'AaaaRecord', {
-      zone: props.hostedZone,
-      target: route53.RecordTarget.fromAlias(new targets.CloudFrontTarget(distribution)),
-      recordName: props.recordName,
-    });
+    };
+    new route53.ARecord(this, 'ARecord', aliasProps);
+    new route53.AaaaRecord(this, 'AaaaRecord', aliasProps);
+    new route53.HttpsRecord(this, 'HttpsRecord', aliasProps);
 
     // Lambda function to increment counter and write redirect in bucket
     const shortenerFunction = new ShortenerFunction(this, 'Shortener', {

.gitignore

@@ -0,0 +1,34 @@
+import { GetObjectCommand, S3Client } from '@aws-sdk/client-s3';
+
+const s3Client = new S3Client({});
+
+export async function handler(event: AWSLambda.LambdaFunctionURLEvent): Promise<AWSLambda.LambdaFunctionURLResult> {
+  try {
+    const key = event.rawPath.substring(1); // remove first slash
+
+    const data = await s3Client.send(new GetObjectCommand({
+      Bucket: process.env.BUCKET_NAME,
+      Key: key,
+    }));
+
+    if (!data.Body) {
+      throw new Error('No body');
+    }
+
+    const redirect = JSON.parse(await data.Body.transformToString());
+
+    if (!redirect.url) {
+      throw new Error('Redirect object in S3 is missing a `url` property.');
+    }
+
+    return {
+      statusCode: 301,
+      headers: {
+        Location: redirect.url,
+      },
+    };
+  } catch (err) {
+    console.log(err);
+    return { statusCode: 404 };
+  }
+}