This topic introduces the terms related to Resource Orchestration Service (ROS).

Term Description
template A JSON, YAML, or Terraform file encoded in UTF-8. You can save template files with file extensions such as .json, .yaml, .template, .txt, or .tf. Templates are used to create stacks and serve as the blueprint for the underlying infrastructure and architecture. Templates define the configurations and dependencies of Alibaba Cloud resources.
stack A collection of ROS resources that you can manage as a unit. You can create, update, or delete a stack to create, update, or delete a group of resources.
stack group A collection of ROS stacks that you can manage as a unit. You can apply an ROS template to a stack group to create stacks in multiple Alibaba Cloud accounts across regions. The ROS template of the stack group defines all resources included in each stack.
change set A feature that is used to update running stacks and serves as a summary of proposed changes. You can preview the impacts that specific changes made to a stack will have on the running resources. ROS modifies your stacks only if you execute change sets.
drift detection A feature that is used to detect whether the actual configurations of stack resources differ, or have drifted, from the expected configurations. You can then take corrective measures to resynchronize resources with their template definitions. Drift correction helps ensure that changes in resources can be identified and that relevant actions can be taken.
tag A key-value pair that can be used to label and classify ROS stacks or templates.