s3 presigned request does not work with custom endpoint and no region set

[ibotty]

If using an aws-config with custom endpoint, but no region the presigned request is not complete. If setting the region it works allright.

Is that expected? If so it would be great to at least document it or better statically prohibit using it without region.

let aws_config = aws_config::from_env()
    .endpoint_url(...)
    //.region("us-east-1")
    .load()
    .await;
let client = aws_sdk_s3::Client::from_conf(s3_config);
let req = client.get_object()
    .bucket(..)
    .key("test-key")
    .presigned(..)
    .await.unwrap();
assert_eq(req.uri, "/test-key/?x-id=GetObject")

[rcoh]

signing requires a region as an inherent part of signing, so any request needs a region. Unfortunately, there isn't a practical way to prohibit this statically, since, e.g. a region could be set as late as config override when customizing the request.

[ibotty]

Yes, it has to be signed. I do now set a default region, but I do think that's not the best API. My testing shows the region does not matter when using a custom endpoint, so it should be optional. Am I wrong in this regard?

[rcoh]

If the SDK was designed to exclusively work with services like Ceph, that may be a reasonable strategy. However, for most AWS customers, there is no good default region (and setting one automatically or having a default) would almost certainly be the wrong thing.

[ibotty]

I do understand that (and don't want to convince you otherwise), but do users on AWS set an endpoint URL? I don't when deploying on AWS, but I am most likely missing things.

[rcoh]

There are a few use cases where it is required, things like S3 VPC endpoints, localstack, etc. It's fairly rare, but does happen.

[ibotty]

Ah, I see. Maybe it could be at least documented, that setting an endpoint is not sufficient without also setting a region somehow.

Thank you for the friendly discussion. Very appreciated.