Heat is OpenStack's orchestration service designed to manage the deployment and lifecycle of composite cloud applications through template-based infrastructure automation. The service provides both an OpenStack-native REST API and a CloudFormation-compatible Query API, enabling users to define complex multi-resource deployments declaratively. Written in Python, Heat serves as a core component of the OpenStack ecosystem for infrastructure-as-code and automated provisioning workflows.
The repository functions as a mirror of code maintained at opendev.org and encompasses the Heat engine and orchestration framework. Heat enables users to define cloud applications using templates that describe the resources, their relationships, and configurations needed for deployment. The service abstracts away the complexity of provisioning multiple cloud resources by allowing operators and developers to specify entire application stacks in a single template definition, which Heat then orchestrates into running infrastructure.
Heat's architecture integrates extensively with other OpenStack services to provide comprehensive cloud resource management. The service maintains integrations with Nova for compute instances, Keystone for authentication, Swift for object storage, Neutron for networking, Cinder for block storage, Glance for image management, Trove for database services, Barbican for key management, Designate for DNS, Magnum for container orchestration, Manila for shared file systems, Mistral for workflow automation, Zaqar for messaging, Zun for container management, Blazar for resource reservations, Octavia for load balancing, Vitrage for root cause analysis, and Ironic for baremetal provisioning. This broad integration ecosystem allows Heat to orchestrate deployments spanning compute, storage, networking, and specialized services within OpenStack environments.
The repository includes comprehensive documentation available at docs.openstack.org, separate template samples maintained in the heat-templates repository, agent components in the heat-agents repository, and release notes documenting version changes. A Python client library, python-heatclient, provides programmatic access to Heat's APIs with its own documentation and source code repository. The project uses StoryBoard for issue and feature tracking, with a dedicated Heat project group containing sub-projects for different Heat components.
Heat's design draws inspiration from AWS CloudFormation, implementing compatible APIs while extending functionality for OpenStack-specific resources and capabilities. The service supports both OpenStack Heat Orchestration Template format and CloudFormation template syntax, enabling users familiar with AWS infrastructure-as-code practices to apply similar patterns within OpenStack environments. This dual API support positions Heat as a bridge technology for organizations transitioning between cloud platforms or managing multi-cloud deployments.
The codebase is actively maintained as part of the OpenStack project governance structure, indicated by the presence of governance badges and integration with OpenStack's development infrastructure. The service addresses the core need for declarative infrastructure automation, allowing teams to version control infrastructure definitions, reproduce deployments consistently, and manage complex application stacks through template-driven orchestration rather than manual resource provisioning.
