Merge branch 'sh-lfs-replace-deleted-file' into 'master'

Gracefully recover from deleted LFS file

See merge request gitlab-org/gitlab!45459

app/controllers/repositories/lfs_storage_controller.rb

@@ -59,10 +59,17 @@ module Repositories
       params[:size].to_i
     end
 
+    def uploaded_file
+      params[:file]
+    end
+
     # rubocop: disable CodeReuse/ActiveRecord
     def store_file!(oid, size)
       object = LfsObject.find_by(oid: oid, size: size)
-      unless object&.file&.exists?
+
+      if object
+        replace_file!(object) unless object.file&.exists?
+      else
         object = create_file!(oid, size)
       end
 
@@ -73,12 +80,19 @@ module Repositories
     # rubocop: enable CodeReuse/ActiveRecord
 
     def create_file!(oid, size)
-      uploaded_file = params[:file]
       return unless uploaded_file.is_a?(UploadedFile)
 
       LfsObject.create!(oid: oid, size: size, file: uploaded_file)
     end
 
+    def replace_file!(lfs_object)
+      raise UploadedFile::InvalidPathError unless uploaded_file.is_a?(UploadedFile)
+
+      Gitlab::AppJsonLogger.info(message: "LFS file replaced because it did not exist", oid: oid, size: size)
+      lfs_object.file = uploaded_file
+      lfs_object.save!
+    end
+
     def link_to_project!(object)
       return unless object
 

changelogs/unreleased/sh-lfs-replace-deleted-file.yml

+---
+title: Gracefully recover from deleted LFS file
+merge_request: 45459
+author:
+type: fixed

spec/controllers/repositories/lfs_storage_controller_spec.rb

@@ -127,6 +127,41 @@ RSpec.describe Repositories::LfsStorageController do
           end
         end
 
+        context 'when existing file has been deleted' do
+          let(:lfs_object) { create(:lfs_object, :with_file) }
+
+          before do
+            FileUtils.rm(lfs_object.file.path)
+            params[:oid] = lfs_object.oid
+            params[:size] = lfs_object.size
+          end
+
+          it 'replaces the file' do
+            expect(Gitlab::AppJsonLogger).to receive(:info).with(message: "LFS file replaced because it did not exist", oid: lfs_object.oid, size: lfs_object.size)
+
+            subject
+
+            expect(response).to have_gitlab_http_status(:ok)
+            expect(lfs_object.reload.file).to exist
+          end
+
+          context 'with invalid file' do
+            before do
+              allow_next_instance_of(ActionController::Parameters) do |params|
+                allow(params).to receive(:[]).and_call_original
+                allow(params).to receive(:[]).with(:file).and_return({})
+              end
+            end
+
+            it 'renders LFS forbidden' do
+              subject
+
+              expect(response).to have_gitlab_http_status(:forbidden)
+              expect(lfs_object.reload.file).not_to exist
+            end
+          end
+        end
+
         context 'when file is not stored' do
           it 'renders unprocessable entity' do
             expect(controller).to receive(:store_file!).and_return(nil)