Rewrite of the LFS server (#15523)

* Restructured code. Moved static checks out of loop.

* Restructured batch api. Add support for individual errors.

* Let router decide if LFS is enabled.

* Renamed methods.

* Return correct status from verify handler.

* Unified media type check in router.

* Changed error code according to spec.

* Moved checks into router.

* Removed invalid v1 api methods.

* Unified methods.

* Display better error messages.

* Added size parameter. Create meta object on upload.

* Use object error on invalid size.

* Skip upload if object exists.

* Moved methods.

* Suppress fields in response.

* Changed error on accept.

* Added tests.

* Use ErrorResponse object.

* Test against message property.

* Add support for the old invalid lfs client.

* Fixed the check because MinIO wraps the error.

* Use individual repositories.

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lauris BH <lauris@nix.lv>

modules/lfs/shared.go

@@ -45,7 +45,7 @@ type BatchResponse struct {
 // ObjectResponse is object metadata as seen by clients of the LFS server.
 type ObjectResponse struct {
 	Pointer
-	Actions map[string]*Link `json:"actions"`
+	Actions map[string]*Link `json:"actions,omitempty"`
 	Error   *ObjectError     `json:"error,omitempty"`
 }
 
@@ -53,7 +53,7 @@ type ObjectResponse struct {
 type Link struct {
 	Href      string            `json:"href"`
 	Header    map[string]string `json:"header,omitempty"`
-	ExpiresAt time.Time         `json:"expires_at,omitempty"`
+	ExpiresAt *time.Time        `json:"expires_at,omitempty"`
 }
 
 // ObjectError defines the JSON structure returned to the client in case of an error
@@ -67,3 +67,10 @@ type PointerBlob struct {
 	Hash string
 	Pointer
 }
+
+// ErrorResponse describes the error to the client.
+type ErrorResponse struct {
+	Message          string
+	DocumentationURL string `json:"documentation_url,omitempty"`
+	RequestID        string `json:"request_id,omitempty"`
+}