Keep failed renames in redis

lib/gitlab/database/rename_reserved_paths_migration/v1/rename_base.rb

@@ -134,12 +134,24 @@ module Gitlab
 
           def reverts_for_type(type)
             key = redis_key_for_type(type)
+
             Gitlab::Redis.with do |redis|
+              failed_reverts = []
+
               while rename_info = redis.lpop(key)
                 path_before_rename, path_after_rename = JSON.parse(rename_info)
                 say "renaming #{type} from #{path_after_rename} back to #{path_before_rename}"
-                yield(path_before_rename, path_after_rename)
+                begin
+                  yield(path_before_rename, path_after_rename)
+                rescue StandardError => e
+                  failed_reverts << rename_info
+                  say "Renaming #{type} from back to #{path_before_rename} failed. "\
+                      "Review the error and try again by running the `down` action. \n"\
+                      "#{e.message}: \n #{e.backtrace.join("\n")}"
+                end
               end
+
+              failed_reverts.each { |rename_info| redis.lpush(key, rename_info) }
             end
           end
 

spec/lib/gitlab/database/rename_reserved_paths_migration/v1/rename_base_spec.rb

@@ -257,5 +257,24 @@ describe Gitlab::Database::RenameReservedPathsMigration::V1::RenameBase, :trunca
       expect { |b| subject.reverts_for_type('namespace', &b) }
         .to yield_with_args('namespace_path', 'new_namespace_path')
     end
+
+    it 'keeps the revert in redis if it failed' do
+      subject.track_rename('project', 'old_path', 'new_path')
+
+      subject.reverts_for_type('project') do
+        raise 'whatever happens, keep going!'
+      end
+
+      key = 'rename:FakeRenameReservedPathMigrationV1:project'
+      stored_renames = nil
+      rename_count = 0
+      Gitlab::Redis.with do |redis|
+        stored_renames = redis.lrange(key, 0, 1)
+        rename_count = redis.llen(key)
+      end
+
+      expect(rename_count).to eq(1)
+      expect(JSON.parse(stored_renames.first)).to eq(%w(old_path new_path))
+    end
   end
 end