Require storage drivers to report their name

Signed-off-by: Stephen J Day <stephen.day@docker.com>

docs/storage/driver/azure/azure.go

@@ -94,6 +94,9 @@ func New(accountName, accountKey, container, realm string) (*Driver, error) {
 }
 
 // Implement the storagedriver.StorageDriver interface.
+func (d *driver) Name() string {
+	return driverName
+}
 
 // GetContent retrieves the content stored at "path" as a []byte.
 func (d *driver) GetContent(path string) ([]byte, error) {

docs/storage/driver/filesystem/driver.go

@@ -71,6 +71,10 @@ func New(rootDirectory string) *Driver {
 
 // Implement the storagedriver.StorageDriver interface
 
+func (d *driver) Name() string {
+	return driverName
+}
+
 // GetContent retrieves the content stored at "path" as a []byte.
 func (d *driver) GetContent(path string) ([]byte, error) {
 	rc, err := d.ReadStream(path, 0)

docs/storage/driver/inmemory/driver.go

@@ -64,6 +64,10 @@ func New() *Driver {
 
 // Implement the storagedriver.StorageDriver interface.
 
+func (d *driver) Name() string {
+	return driverName
+}
+
 // GetContent retrieves the content stored at "path" as a []byte.
 func (d *driver) GetContent(path string) ([]byte, error) {
 	d.mutex.RLock()

docs/storage/driver/s3/s3.go

@@ -261,6 +261,10 @@ func New(params DriverParameters) (*Driver, error) {
 
 // Implement the storagedriver.StorageDriver interface
 
+func (d *driver) Name() string {
+	return driverName
+}
+
 // GetContent retrieves the content stored at "path" as a []byte.
 func (d *driver) GetContent(path string) ([]byte, error) {
 	content, err := d.Bucket.Get(d.s3Path(path))

docs/storage/driver/storagedriver.go

@@ -35,6 +35,11 @@ const CurrentVersion Version = "0.1"
 // StorageDriver defines methods that a Storage Driver must implement for a
 // filesystem-like key/value object storage.
 type StorageDriver interface {
+	// Name returns the human-readable "name" of the driver, useful in error
+	// messages and logging. By convention, this will just be the registration
+	// name, but drivers may provide other information here.
+	Name() string
+
 	// GetContent retrieves the content stored at "path" as a []byte.
 	// This should primarily be used for small objects.
 	GetContent(path string) ([]byte, error)