Add support for plugin backends

plugins/plugins.go

@@ -0,0 +1,21 @@
+package plugins
+
+import "github.com/versity/versitygw/backend"
+
+// BackendPlugin defines an interface for creating backend
+// implementation instances.
+// Plugins implementing this interface can be built as shared
+// libraries using Go's plugin system (to build use `go build -buildmode=plugin`).
+// The shared library should export an instance of
+// this interface in a variable named `Backend`.
+type BackendPlugin interface {
+	// New creates and initializes a new backend.Backend instance.
+	// The config parameter specifies the path of the file containing
+	// the configuration for the backend.
+	//
+	// Implementations of this method should perform the necessary steps to
+	// establish a connection to the underlying storage system or service
+	// (e.g., network storage system, distributed storage system, cloud storage)
+	//  and configure it according to the provided configuration.
+	New(config string) (backend.Backend, error)
+}