From b1edb5cfd9e2761a5715152e06532a6c6f8b85b7 Mon Sep 17 00:00:00 2001
From: Patrick Jungermann <Patrick.Jungermann@gmail.com>
Date: Wed, 15 Jun 2022 14:25:19 +0200
Subject: [PATCH] fix: fix parsing of S3 URLs for the default region

Closes: #11913
Signed-off-by: Patrick Jungermann <Patrick.Jungermann@gmail.com>
---
 .changeset/chilled-mirrors-grab.md                       | 5 +++++
 .../backend-common/src/reading/AwsS3UrlReader.test.ts    | 9 +++++++++
 packages/backend-common/src/reading/AwsS3UrlReader.ts    | 8 +++++---
 3 files changed, 19 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/chilled-mirrors-grab.md

diff --git a/.changeset/chilled-mirrors-grab.md b/.changeset/chilled-mirrors-grab.md
new file mode 100644
index 0000000000..ecc95680e2
--- /dev/null
+++ b/.changeset/chilled-mirrors-grab.md
@@ -0,0 +1,5 @@
+---
+'@backstage/backend-common': patch
+---
+
+Fix parsing of S3 URLs for the default region.
diff --git a/packages/backend-common/src/reading/AwsS3UrlReader.test.ts b/packages/backend-common/src/reading/AwsS3UrlReader.test.ts
index 0ae64e9404..454b8a2c5a 100644
--- a/packages/backend-common/src/reading/AwsS3UrlReader.test.ts
+++ b/packages/backend-common/src/reading/AwsS3UrlReader.test.ts
@@ -39,6 +39,15 @@ const treeResponseFactory = DefaultReadTreeResponseFactory.create({
 
 describe('parseUrl', () => {
   it('supports all aws formats', () => {
+    expect(
+      parseUrl('https://s3.amazonaws.com/my.bucket-3/a/puppy.jpg', {
+        host: 'amazonaws.com',
+      }),
+    ).toEqual({
+      path: 'a/puppy.jpg',
+      bucket: 'my.bucket-3',
+      region: 'us-east-1',
+    });
     expect(
       parseUrl('https://s3.us-west-2.amazonaws.com/my.bucket-3/a/puppy.jpg', {
         host: 'amazonaws.com',
diff --git a/packages/backend-common/src/reading/AwsS3UrlReader.ts b/packages/backend-common/src/reading/AwsS3UrlReader.ts
index b0ac81676a..7c314cf036 100644
--- a/packages/backend-common/src/reading/AwsS3UrlReader.ts
+++ b/packages/backend-common/src/reading/AwsS3UrlReader.ts
@@ -35,6 +35,8 @@ import { ForwardedError, NotModifiedError } from '@backstage/errors';
 import { ListObjectsV2Output, ObjectList } from 'aws-sdk/clients/s3';
 import { ReadUrlResponseFactory } from './ReadUrlResponseFactory';
 
+const DEFAULT_REGION = 'us-east-1';
+
 /**
  * Path style URLs: https://s3.(region).amazonaws.com/(bucket)/(key)
  * The region can also be on the old form: https://s3-(region).amazonaws.com/(bucket)/(key)
@@ -57,7 +59,7 @@ export function parseUrl(
   // Treat Amazon hosted separately because it has special region logic
   if (config.host === 'amazonaws.com') {
     const match = host.match(
-      /^(?:([a-z0-9.-]+)\.)?s3[.-]([a-z0-9-]+)\.amazonaws\.com$/,
+      /^(?:([a-z0-9.-]+)\.)?s3(?:[.-]([a-z0-9-]+))?\.amazonaws\.com$/,
     );
     if (!match) {
       throw new Error(`Invalid AWS S3 URL ${url}`);
@@ -76,14 +78,14 @@ export function parseUrl(
       return {
         path: pathname.substring(slashIndex + 1),
         bucket: pathname.substring(0, slashIndex),
-        region: hostRegion,
+        region: hostRegion ?? DEFAULT_REGION,
       };
     }
 
     return {
       path: pathname,
       bucket: hostBucket,
-      region: hostRegion,
+      region: hostRegion ?? DEFAULT_REGION,
     };
   }