1 files changed, 106 insertions, 0 deletions
diff --git a/app/services/bulk_imports/relation_export_service.rb b/app/services/bulk_imports/relation_export_service.rb
new file mode 100644
index 00000000000..53952a33b5f
--- /dev/null
+++ b/app/services/bulk_imports/relation_export_service.rb
@@ -0,0 +1,106 @@
+# frozen_string_literal: true
+
+module BulkImports
+  class RelationExportService
+    include Gitlab::ImportExport::CommandLineUtil
+
+    def initialize(user, portable, relation, jid)
+      @user = user
+      @portable = portable
+      @relation = relation
+      @jid = jid
+    end
+
+    def execute
+      find_or_create_export! do |export|
+        remove_existing_export_file!(export)
+        serialize_relation_to_file(export.relation_definition)
+        compress_exported_relation
+        upload_compressed_file(export)
+      end
+    end
+
+    private
+
+    attr_reader :user, :portable, :relation, :jid
+
+    def find_or_create_export!
+      validate_user_permissions!
+
+      export = portable.bulk_import_exports.safe_find_or_create_by!(relation: relation)
+      export.update!(status_event: 'start', jid: jid)
+
+      yield export
+
+      export.update!(status_event: 'finish', error: nil)
+    rescue StandardError => e
+      Gitlab::ErrorTracking.track_exception(e, portable_id: portable.id, portable_type: portable.class.name)
+
+      export&.update(status_event: 'fail_op', error: e.class)
+    end
+
+    def validate_user_permissions!
+      ability = "admin_#{portable.to_ability_name}"
+
+      user.can?(ability, portable) ||
+        raise(::Gitlab::ImportExport::Error.permission_error(user, portable))
+    end
+
+    def remove_existing_export_file!(export)
+      upload = export.upload
+
+      return unless upload&.export_file&.file
+
+      upload.remove_export_file!
+      upload.save!
+    end
+
+    def serialize_relation_to_file(relation_definition)
+      serializer.serialize_relation(relation_definition)
+    end
+
+    def compress_exported_relation
+      gzip(dir: export_path, filename: ndjson_filename)
+    end
+
+    def upload_compressed_file(export)
+      compressed_filename = File.join(export_path, "#{ndjson_filename}.gz")
+      upload = ExportUpload.find_or_initialize_by(export_id: export.id) # rubocop: disable CodeReuse/ActiveRecord
+
+      File.open(compressed_filename) { |file| upload.export_file = file }
+
+      upload.save!
+    end
+
+    def config
+      @config ||= FileTransfer.config_for(portable)
+    end
+
+    def export_path
+      @export_path ||= config.export_path
+    end
+
+    def portable_tree
+      @portable_tree ||= config.portable_tree
+    end
+
+    # rubocop: disable CodeReuse/Serializer
+    def serializer
+      @serializer ||= ::Gitlab::ImportExport::JSON::StreamingSerializer.new(
+        portable,
+        portable_tree,
+        json_writer,
+        exportable_path: ''
+      )
+    end
+    # rubocop: enable CodeReuse/Serializer
+
+    def json_writer
+      @json_writer ||= ::Gitlab::ImportExport::JSON::NdjsonWriter.new(export_path)
+    end
+
+    def ndjson_filename
+      @ndjson_filename ||= "#{relation}.ndjson"
+    end
+  end
+end