Middleware prefix blobstore

Middleware: Prefix BlobStore

Use the prefix middleware when you want a single S3 bucket exposed by S3Proxy to map onto a fixed prefix inside a backend bucket. This is useful when an upstream consumer cannot specify object prefixes but your storage layout requires them.

Enable the middleware by adding one property per bucket that should be scoped to a prefix:

s3proxy.prefix-blobstore.<bucket-name>=<prefix>

For example, to expose scoped-data/ objects from your backend storage as if they were located at the top of customer-bucket:

s3proxy.prefix-blobstore.customer-bucket=scoped-data/

With this configuration all reads, writes, listings, and multipart uploads issued to the customer-bucket bucket will transparently operate under the scoped-data/ prefix on the backend. Objects stored outside the configured prefix remain untouched, and deleting the virtual bucket contents only affects objects within the scoped prefix.

Multiple buckets can be configured and each bucket may define at most one prefix.

Note: Prefix scoping currently refuses to wrap providers listed in Quirks.OPAQUE_MARKERS (e.g., Google Cloud Storage, Backblaze B2, Azure Blob) because their pagination semantics differ from Amazon S3.