S3 backend for storage service (#1629)

Co-authored-by: Alok Kumar <rajalokan@gmail.com>

pkg/storagesvc/localstorage.go

@@ -0,0 +1,52 @@
+package storagesvc
+
+import (
+	"os"
+
+	"github.com/graymeta/stow"
+	_ "github.com/graymeta/stow/local"
+	uuid "github.com/satori/go.uuid"
+)
+
+type localStorage struct {
+	storageType   StorageType
+	containerName string
+	localPath     string
+}
+
+// NewLocalStorage return new local storage struct
+func NewLocalStorage(localPath string) Storage {
+	subdir := os.Getenv("SUBDIR")
+	if len(subdir) == 0 {
+		subdir = "fission-functions"
+	}
+	return localStorage{
+		storageType:   StorageTypeLocal,
+		containerName: subdir,
+		localPath:     localPath,
+	}
+}
+
+// Local
+func (ls localStorage) getStorageType() StorageType {
+	return ls.storageType
+}
+
+func (ls localStorage) SetLocalPath(path string) {
+	ls.localPath = path
+}
+
+func (ls localStorage) getUploadFileName() string {
+	// This is not the item ID (that's returned by Put)
+	// should we just use handler.Filename? what are the constraints here?
+	return uuid.NewV4().String()
+}
+
+func (ls localStorage) getContainerName() string {
+	return ls.containerName
+}
+
+func (ls localStorage) dial() (stow.Location, error) {
+	cfg := stow.ConfigMap{"path": ls.localPath}
+	return stow.Dial("local", cfg)
+}