5.2. Environment Files

An environment file is a special type of template that provides customization for your Heat templates. This includes three key parts:
  • Parameters - These are common settings you apply to a template's parameters. These are defined in the parameters section of an environment file.
  • Parameter Defaults - These parameters modify the default values for parameters in your templates. These are defined in the parameter_defaults section of an environment file.
  • Resource Registry - This section defines custom resource names, link to other Heat templates. This essentially provides a method to create custom resources that do not exist within the core resource collection. These are defined in the resource_registry section of an environment file.
Here is an example of a basic environment file: 
resource_registry:
  OS::Nova::Server::MyServer: myserver.yaml

parameter_defaults:
  NetworkName: my_network

parameters:
  MyIP: 192.168.0.1
This creates a new resource type called OS::Nova::Server::MyServer. The myserver.yaml file is a Heat template file that provides an implementation for this resource type that overrides any built-in ones.