Custom domain cannot be configured for ap-northeast-1 region

[YutakaShimokawa]

Describe the bug
After deploying a stack to the ap-northeast-1 region and configuring a custom domain, sigv4 authentication fails and login becomes impossible.

To Reproduce

1. Deploy in ap-northeast-1 region
2. Configure custom domain refering to the following manual

https://github.com/aws-solutions/qnabot-on-aws/blob/771b4b465266c19fb863a38c2aa0cd80bf665e96/docs/custom_domain_name_setup/README.md

Expected behavior
Able to login

Please complete the following information about the solution:

• Version: v5.2.2

• Region: ap-northeast-1

• Was the solution modified from the version published on this repository?: No

• If the answer to the previous question was yes, are the changes available on GitHub?: -

• Have you checked your service quotas for the sevices this solution uses?: Yes, and no alart

• Were there any errors in the CloudWatch Logs?: No

[YutakaShimokawa]

I think it is probably due to the fact that the aws4 library in the following section is set to us-east-1 when the region cannot be determined from the URL path.
https://github.com/aws-solutions/qnabot-on-aws/blob/ecdf9f887bb1cd0688421b57c6809eea6ccd4609/website/js/lib/store/api/actions/index.js

[ihmaws]

Thanks for the report @YutakaShimokawa and sorry for the delay in getting back to you!

The team will have a look and add it into the backlog for investigation.

[jangidms]

Hi @YutakaShimokawa
Sorry for the delayed response. We are planning a fix for this issue. Please continue to monitor repo for updates

[jangidms]

Hi @YutakaShimokawa
This issue has been fixed in release 5.4.2