Accessing Keep using S3 protocol¶

See #16360

As of 2020-08-24 7a7a1395490eb9b9789b79f88a77fe709a898feb there is experimental support for accessing Arvados projects and collections as S3 buckets.

Client configuration:

• S3 endpoint: Services.WebDAV.ExternalURL
• bucket name: UUID of a project or collection
• Access key: Arvados API token
• Secret key: any string (not used)

Supported operations:

• GetBucketVersioning
• HeadBucket
• HeadObject
• GetObject
• PutObject
• DeleteObject

Planned, but not yet supported:

• DeleteObjects
• POST Object