Backend capabilities

What each driver in internal/backend/ advertises through the Capabilities struct. The dashboard hides UI affordances when the capability is false or zero.

#The Capabilities shape

From internal/backend/backend.go:

type Capabilities struct {
    Versioning        bool
    ObjectLock        bool
    Lifecycle         bool
    BucketPolicy      bool
    CORS              bool
    Tagging           bool
    ServerSideEncrypt bool
    AdminAPI          string  // "" | "minio" | "garage" | "seaweedfs"
    MaxMultipartParts int
    MaxPartSizeBytes  int64
}

#Per-driver matrix

The s3v4 driver is the production driver — it's what every YAML or UI-managed backend uses. Capability flags are advertised optimistically; the dashboard surfaces upstream errors when the upstream actually rejects an operation it claimed to support.

#When AdminAPI is non-empty

Capabilities.AdminAPI is a marker for native admin-API screens (create users, attach policies, etc.) inside the dashboard. Today it returns "" for every driver; the screens are gated on this and so remain hidden.

When the minio, garage, or seaweedfs drivers ship, their AdminAPI returns will flip to those literals and the dashboard grows the corresponding admin views.

#What drives the UI matrix

• bucket-settings panel for versioning, CORS, policy, lifecycle appears only when the matching capability is true.
• The Object lock column on the bucket detail page is hidden when ObjectLock=false.
• Tags and user metadata editors are hidden when Tagging=false.
• Multipart UI uses MaxMultipartParts and MaxPartSizeBytes to pre-validate large uploads.

#Adding a driver

To add a driver (say, garage with native admin API):

1. Implement the Backend interface under internal/backend/garage/.
2. Implement AdminBackend (the optional escape hatch in backend.go).
3. Have Capabilities() return AdminAPI: "garage".
4. Register the driver in internal/backend/registry.go so type: garage config entries resolve.
5. Add UI screens that consume the AdminAPI capability.

The deferred drivers are tracked in Roadmap.