Uploading files using presigned url in af-south-1

[vedantbajaj96]

Unable to upload data using presigned url in af-south-1 region.

Steps to reproduce

s3_client = boto3.client('s3', region_name='af-south-1')
res = s3_client.generate_presigned_post(Bucket=bucket_name, Key=object_key)
http_response = requests.post(res['url'], data=url['fields'], files=files)

The response I get is IllegalLocationConstraintException. The af-south-1 location constraint is incompatible for the region specific endpoint this request was sent to.

The same code works with buckets in other regions.

Boto3 version - 1.16.56
Interestingly, the same code works with boto3 version < 1.12

[vedantbajaj96]

Upon further inspection, it seems when i pass the endpoint url while generating the s3 client, it works then.

    s3_client = boto3.client('s3',region_name='af-south-1', endpoint_url='https://s3.af-south-1.amazonaws.com')

But I dont see this issue on older versions of boto3, or with some of the other regions.

[swetashre]

Amazon S3 uses the Domain Name System (DNS) to route requests to facilities that can process them. This system works effectively, but temporary routing errors can occur. If a request arrives at the wrong Amazon S3 location, Amazon S3 responds with a temporary redirect that tells the requester to resend the request to a new endpoint. If a request is incorrectly formed, Amazon S3 uses permanent redirects to provide direction on how to perform the request correctly.

For all Regions that launched after March 20, 2019, if a request arrives at the wrong Amazon S3 location, Amazon S3 returns an HTTP 400 Bad Request error. Basically this means s3 region re-director won't work for region launched after march 20, 2019.
That's why when you are specifying the exact endpoint_url it works. I hope it helps. Please let me know if you have any more questions.