Glossary

API server

HTTP REST API service for heat.

CFN

An abbreviated form of “AWS CloudFormation”.

Constraint

Defines valid input parameters for a template.

Dependency

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.

Environment

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.

HOT

An acronym for “Heat Orchestration Template”.

Input parameters

See Parameters.

Metadata

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 Metadata service (OpenStack Cloud Admin Guide).

Multi-region

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 Compute Admin Guide).

OpenStack

Open source software for building private and public clouds.

Orchestrate

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

Outputs

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

Parameters

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. See What are “Providers”? (OpenStack Wiki).

Provider template

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

Resource

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.

Stack

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.

Template

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 User data (OpenStack End User Guide).

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.