mappings

The mappings section is optional and defines a mapping table. When creating a stack based on a template, you can use the get_in_map function to extract the content corresponding to a specific variable. A maximum of 10 mappings sections can be defined in a template.

Format of the mappings section:

 <Mapping name>:
    <Mapping object name>:
       <Mapping object property name>: <Mapping object property value>
       <Mapping object property name>: <Mapping object property value>
       ...
    ...
 ...

**Table 1** Parameter property description
Property	Mandatory	Type	Value Constraint	Description
Mapping name	Yes	String	The value must be 1 to 64 characters long. Only letters, digits, and hyphens (-) are allowed.	A maximum of 10 mapping names can be defined and each name must be unique.
Mapping object name	Yes	String	The value must be 1 to 64 characters long. Only letters, digits, and hyphens (-) are allowed.	Name of a mapping object, which must be unique.
Mapping object property name	Yes	String	The value must be 1 to 64 characters long. Only letters, digits, and hyphens (-) are allowed.	Property name of a mapping object. Each name must be unique in the same mapping object.
Mapping object property value	Yes	String or digit	String or digit	Property value corresponding to a mapping object.

Example configuration of mappings:

mappings:
  regionMap:
    cn-east-3:   # Defines the East China region.
      flavor: c2.medium    # Indicates the VM specifications of the East China region.
      image_id: f2003c7b-99c4-4616-be19-334beaca81b1   # Indicates the image ID of the East China region.
    cn-north-1:  # Defines the North China region.
      flavor: c1.medium    # Indicates the VM specifications of the North China region.
      image_id: 42f34d95-a538-4d17-be48-e690b48c1643   # Indicates the image ID of the North China region. 
    cn-south-1:   # Defines the South China region.
      flavor: c1.medium    # Indicates the VM specifications of the South China region.
      image_id: a3934478-bfeb-4a02-b257-9089779f0380   # Indicates the image ID of the South China region.

Usage mode of mappings:

The defined mappings can be used in node_templates or outputs.

Use the get_in_map function to extract the mapping content from node_templates.
For example, the myecs object is defined in node_templates, and its properties include the image ID and VM specifications. The image ID and VM specifications must have been predefined in mappings. During stack creation based on the template, the required image and VM specifications of the corresponding region will be used.
```
node_templates:
  myecs:
    type: HuaweiCloud.ECS.CloudServer
    properties:
      availabilityZone: cn-south-1a
      flavor:
        get_in_map:
          - regionMap
          - get_input: HuaweiCloud.Region
          - flavor
      imageId:
        get_in_map:
          - regionMap
          - get_input: HuaweiCloud.Region
          - image_id
      ...
```

Use the get_in_map function to extract the mapping content from outputs.

outputs:
  south-flavor:
    description: VM specifications of the South China region
    value:
      get_in_map:
        - regionMap
        - cn-south-1
        - flavor

Parent topic: Template Introduction

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