Provide self-registering storage system (#12978)

* Provide self-registering storage system

Signed-off-by: Andrew Thornton <art27@cantab.net>

* More simplification

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Remove old strings from setting

Signed-off-by: Andrew Thornton <art27@cantab.net>

* oops attachments not attachment

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

modules/storage/local.go

@@ -5,6 +5,7 @@
 package storage
 
 import (
+	"context"
 	"io"
 	"net/url"
 	"os"
@@ -17,19 +18,35 @@ var (
 	_ ObjectStorage = &LocalStorage{}
 )
 
+// LocalStorageType is the type descriptor for local storage
+const LocalStorageType Type = "local"
+
+// LocalStorageConfig represents the configuration for a local storage
+type LocalStorageConfig struct {
+	Path string `ini:"PATH"`
+}
+
 // LocalStorage represents a local files storage
 type LocalStorage struct {
+	ctx context.Context
 	dir string
 }
 
 // NewLocalStorage returns a local files
-func NewLocalStorage(bucket string) (*LocalStorage, error) {
-	if err := os.MkdirAll(bucket, os.ModePerm); err != nil {
+func NewLocalStorage(ctx context.Context, cfg interface{}) (ObjectStorage, error) {
+	configInterface, err := toConfig(LocalStorageConfig{}, cfg)
+	if err != nil {
+		return nil, err
+	}
+	config := configInterface.(LocalStorageConfig)
+
+	if err := os.MkdirAll(config.Path, os.ModePerm); err != nil {
 		return nil, err
 	}
 
 	return &LocalStorage{
-		dir: bucket,
+		ctx: ctx,
+		dir: config.Path,
 	}, nil
 }
 
@@ -80,6 +97,11 @@ func (l *LocalStorage) IterateObjects(fn func(path string, obj Object) error) er
 		if err != nil {
 			return err
 		}
+		select {
+		case <-l.ctx.Done():
+			return l.ctx.Err()
+		default:
+		}
 		if path == l.dir {
 			return nil
 		}
@@ -98,3 +120,7 @@ func (l *LocalStorage) IterateObjects(fn func(path string, obj Object) error) er
 		return fn(relPath, obj)
 	})
 }
+
+func init() {
+	RegisterStorageType(LocalStorageType, NewLocalStorage)
+}