Variable

The Variable declaration specifies a literal value or an expression. Variables are inlined during compilation. They can be used by other variables, resources, and functions. Variables, like resources, can be scoped to functions, the stack, or to be public.

Syntax

Variable: String
Description: String
Type: String
Scope: ScopeDefinition
Value: Expression
EncryptionContext:
  Key-Value Mapping

Properties

Description

The Description attribute specifies the variable description.

Required: No

Type: String

EncryptionContext

The EncryptionContext section is an optional mapping of key-value pairs used for decrypting a variable of type Secret. For all other types, specifying EncryptionContext will produce a compilation error.

Required: No

Type: Key-Value Pair Mapping

Scope

The Scope attribute specifies which functions need to have access to this item. The Scope attribute can be a comma-separated list or a YAML list of function names. If all functions need the item, then all can be used as a wildcard. In addition, public can be used to export the item from the module. Alternatively, stack can be used to make the item available only in a nested stack.

Required: No

Type: Comma-delimited String or List of String

Type

The Type attribute specifies the variable type. When omitted, the type is String. Encrypted values must have type Secret and can optionally specify an EncryptionContext section. These values can be shared as is, or decrypted, when using the ::Plaintext suffix on the full name.

For example, the decrypted value of a variable called Password with type Secret can be accessed by using !Ref Password::Plaintext.

Value

The Value attribute specifies the value for the variable. The Value can be a literal value, an expression, or a list of expressions.

Required: Yes

Type: Expression

Variable

The Variable attribute specifies the item name. The name must start with a letter and followed only by letters or digits. Punctuation marks are not allowed. All names are case-sensitive.

Required: Yes

Type: String

Return Values

Ref

When the logical ID of this item is provided to the Ref intrinsic function, Ref returns the value of the variable. If the value of the variable is a list, the expressions in the list are concatenated into a comma-separated string.

Examples

Literal value

- Variable: MyValue
  Value: Hello World!

List of literal values

- Variable: MyList
  Value:
    - First
    - Second

Expression value

- Variable: MyExpression
  Value: !Sub "${AWS::StackName}-${AWS::Region}"

List of expressions

- Variable: MyExpressionList
  Value:
    - !Sub "${AWS::StackName}-${Module::FullName}"
    - !Sub "${AWS::StackName}-${AWS::Region}"