Use AWS Java SDK for signing URL

[danielcompton]

We should investigate whether it is possible to use the AWS Java SDK to sign URLs. This would let us support v4 signing format, as well as letting users use the credential chain rather than needing to provide access keys. One thing to watch out for is the dependencies that this might bring along with it.

[danielcompton]

https://docs.aws.amazon.com/AmazonS3/latest/dev/ShareObjectPreSignedURLJavaSDK.html has docs on how to do this.

[danielcompton]

I took a look at this, my findings:

• AWS Java SDK v2 doesn't support generating presigned URLS yet - Presigned URL Generators aws/aws-sdk-java-v2#203
• AWS Java SDK v1 creates presigned URLs using virtual-host style URLs, even if the bucket name has a . in it - Generate presigned URLs with path-style addressing when the bucket has a "." character aws/aws-sdk-java#2105, and Presigned URLs : bucket names containing "." chars + HTTPS aws/aws-sdk-java#628
• AWS Java SDK v1 doesn't seem to create v4 presigned URLs, though I don't think we do now either - Add support for Signature Version 4 #34, Presigned V4 URLs using Java SDK aws/aws-sdk-java#834

Given that there is no urgency to move, I suggest waiting to see if either of these SDK's add support for presigned URLs with "." in the bucket name.