The Orchestration service provides a template-based orchestration for describing a cloud application by running OpenStack API calls to generate running cloud applications. The software integrates other core components of OpenStack into a one-file template system. The templates enable you to create most OpenStack resource types, such as instances, floating IPs, volumes, security groups, users, and so on. Also, provides some more advanced functionality, such as instance high availability, instance auto-scaling, and nested stacks. By providing very tight integration with other OpenStack core projects, all OpenStack core projects could receive a larger user base. The service enables deployers to integrate with the Orchestration service directly or through custom plug-ins. The Orchestration service consists of the following components: heat command-line client. A CLI that communicates with the heat-api to run AWS CloudFormation APIs. End developers could also use the Orchestration REST API directly. heat-api component. Provides an OpenStack-native REST API that processes API requests by sending them to the heat-engine over RPC. heat-api-cfn component. Provides an AWS Query API that is compatible with AWS CloudFormation and processes API requests by sending them to the heat-engine over RPC. heat-engine. Orchestrates the launching of templates and provides events back to the API consumer.