Middleware alias blobstore

S3Proxy can use an alias for a backend bucket. This may be helpful to preserve bucket names when switching backends, for example. The alternate name can be specified as follows:

s3proxy.alias-blobstore.content=backend-data

In the above example, requests for the bucket content are redirected to backend-data. This does not preclude using the name backend-data, however, when listing buckets backend-data bucket is replaced with content in the listing.

S3Proxy does not allow mapping multiple aliases to the same backend bucket. Future work could expand this middleware to include a prefix, allowing a subset of a bucket to appear as a bucket to the S3Proxy clients.