What is responsible for orchestration in OpenStack?

The correct answer is OpenStack Heat Templates, as they are specifically designed for orchestration within the OpenStack ecosystem. Heat is a core component of OpenStack that allows users to define the desired state of their cloud infrastructure using templates written in YAML (Yet Another Markup Language). Through these templates, users can automate the provisioning and management of complex cloud applications by specifying stacks, which are collections of related resources.

By utilizing Heat Templates, developers can create scalable and repeatable deployments, manage dependencies between resources, and implement configurations that enhance the overall efficiency of cloud resource management. This orchestration capability is essential in larger environments where complex applications are deployed across multiple resources and configurations.

The other options, while related to cloud technologies, do not serve the primary role of orchestration in OpenStack. KVM and Ubuntu are related to the cloud infrastructure layer, providing compute and operating system functionalities, rather than orchestration. Contrail, a networking solution, focuses on network virtualization and is not an orchestration tool. Celiometer is used for telemetry and monitoring within the OpenStack environment, but it does not manage the orchestration of resources like Heat does.