The problem only happens when a user has configured the new AWS Frankfurt
region for their S3 backend. It is the only region to require the new
v4 signature. All other regions support both v2 and v4. I'm not sure
which version is used by default on US Standard.
We could attempt to figure out where the bucket is hosted based on its
DNS resolution and auto-populate the host field that way. But I think
the amount of effort to have that work correctly outweighs its benefit
for such a simple solution.
fixes#863fixes#764
The previous change to this file didn't raise the error up to stream_write,
and so the complete_upload function still ran because the loop was only
broken. It errored because the data was already canceled. This is better
than what we had before, which was to silently fail but report success
(even internally to ourselves!) on bad image upload.
This means we discovered a bug where a user could have failed during image
upload, but quay would write that image to the repository, potentially
writing broken images to S3.
