API server

HTTP REST API service for heat.


An abbreviated form of “AWS CloudFormation”.


Defines valid input parameters for a template.


When a resource must wait for another resource to finish creation before being created itself. Heat adds an implicit dependency when a resource references another resource or one of its attributes. An explicit dependency can also be created by the user in the template definition.


Used to affect the run-time behavior of the template. Provides a way to override the default resource implementation and parameters passed to Heat. See Environments.

Heat Orchestration Template

A particular template format that is native to Heat. Heat Orchestration Templates are expressed in YAML and are not backwards-compatible with CloudFormation templates.


An acronym for “Heat Orchestration Template”.

input parameters

See parameters.


May refer to Resource Metadata, Nova Instance metadata, or the Metadata service.

Metadata service

A Compute service that enables virtual machine instances to retrieve instance-specific data. See Nova Metadata service documentation.


A feature of Heat that supports deployment to multiple regions.

nested resource

A resource instantiated as part of a nested stack.

nested stack

A template referenced by URL inside of another template. Used to reduce redundant resource definitions and group complex architectures into logical groups.

Nova Instance metadata

User-provided key:value pairs associated with a Compute Instance. See Instance-specific data (OpenStack Operations Guide).


Open source software for building private and public clouds.


Arrange or direct the elements of a situation to produce a desired effect.


A top-level block in a template that defines what data will be returned by a stack after instantiation.


A top-level block in a template that defines what data can be passed to customise a template when it is used to create or update a stack.

provider resource

A resource implemented by a provider template. The parent resource’s properties become the nested stack’s parameters.

provider template

Allows user-definable resource providers to be specified via nested stacks. The nested stack’s outputs become the parent stack’s attributes.


An element of OpenStack infrastructure instantiated from a particular resource provider. See also nested resource.

resource attribute

Data that can be obtained from a resource, e.g. a server’s public IP or name. Usually passed to another resource’s properties or added to the stack’s outputs.

resource group

A resource provider that creates one or more identically configured resources or nested resources.

Resource Metadata

A resource property that contains CFN-style template metadata. See AWS::CloudFormation::Init (AWS CloudFormation User Guide)

resource plugin

Python code that understands how to instantiate and manage a resource. See Heat Resource Plugins (OpenStack wiki).

resource property

Data utilized for the instantiation of a resource. Can be defined statically in a template or passed in as input parameters.

resource provider

The implementation of a particular resource type. May be a resource plugin or a provider template.


A collection of instantiated resources that are defined in a single template.

stack resource

A resource provider that allows the management of a nested stack as a resource in a parent stack.


An orchestration document that details everything needed to carry out an orchestration.

template resource

See provider resource.

user data

A resource property that contains a user-provided data blob. User data gets passed to cloud-init to automatically configure instances at boot time. See also Nova User data documentation.

wait condition

A resource provider that provides a way to communicate data or events from servers back to the orchestration engine. Most commonly used to pause the creation of the stack while the server is being configured.