distribution/docs/storage/layerhandler.go
Stephen J Day 6e4f9a2e3e Move storagedriver package to registry/storage/driver
This change is slightly more complex than previous package maves in that the
package name changed. To address this, we simply always reference the package
driver as storagedriver to avoid compatbility issues with existing code. While
unfortunate, this can be cleaned up over time.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-02-11 12:43:04 -08:00

51 lines
1.7 KiB
Go

package storage
import (
"fmt"
"net/http"
storagedriver "github.com/docker/distribution/registry/storage/driver"
)
// LayerHandler provides middleware for serving the contents of a Layer.
type LayerHandler interface {
// Resolve returns an http.Handler which can serve the contents of a given
// Layer if possible, or nil and an error when unsupported. This may
// directly serve the contents of the layer or issue a redirect to another
// URL hosting the content.
Resolve(layer Layer) (http.Handler, error)
}
// LayerHandlerInitFunc is the type of a LayerHandler factory function and is
// used to register the contsructor for different LayerHandler backends.
type LayerHandlerInitFunc func(storageDriver storagedriver.StorageDriver, options map[string]interface{}) (LayerHandler, error)
var layerHandlers map[string]LayerHandlerInitFunc
// RegisterLayerHandler is used to register an LayerHandlerInitFunc for
// a LayerHandler backend with the given name.
func RegisterLayerHandler(name string, initFunc LayerHandlerInitFunc) error {
if layerHandlers == nil {
layerHandlers = make(map[string]LayerHandlerInitFunc)
}
if _, exists := layerHandlers[name]; exists {
return fmt.Errorf("name already registered: %s", name)
}
layerHandlers[name] = initFunc
return nil
}
// GetLayerHandler constructs a LayerHandler
// with the given options using the named backend.
func GetLayerHandler(name string, options map[string]interface{}, storageDriver storagedriver.StorageDriver) (LayerHandler, error) {
if layerHandlers != nil {
if initFunc, exists := layerHandlers[name]; exists {
return initFunc(storageDriver, options)
}
}
return nil, fmt.Errorf("no layer handler registered with name: %s", name)
}