AWS CloudFormation Concepts Intrinsic Functions: Difference between revisions
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The intrinsic function Ref returns the value of the specified [[AWS_CloudFormation_Concepts#Input_Parameters|parameter]] or [[AWS_CloudFormation_Concepts#Resources|resource]]. When a parameter logical name is specified, it returns the value of the parameter. When a resource logical name is specified, it returns a value that can be typically used to refer to that resource, such as a physical ID. | The intrinsic function Ref returns the value of the specified [[AWS_CloudFormation_Concepts#Input_Parameters|parameter]] or [[AWS_CloudFormation_Concepts#Resources|resource]]. When a parameter logical name is specified, it returns the value of the parameter. When a resource logical name is specified, it returns a value that can be typically used to refer to that resource, such as a physical ID. | ||
!Ref AWS:: | !Ref AWS::StackName | ||
!Ref MyParameter | !Ref MyParameter | ||
Revision as of 04:41, 14 March 2019
External
Internal
Ref
The intrinsic function Ref returns the value of the specified parameter or resource. When a parameter logical name is specified, it returns the value of the parameter. When a resource logical name is specified, it returns a value that can be typically used to refer to that resource, such as a physical ID.
!Ref AWS::StackName !Ref MyParameter
Join
!Join [ delimiter, [ comma-delimited list of values ] ]
!Join ['-', [ a, b, c ]]
returns "a:b:c"
Split
!Split ['.', "www.example.com"]
returns ["www", "example", "com"].
Select
Sub
Sub substitutes variables in an input string with specified values.
If only template parameters, resource logical IDs and resource attributes are substituted in the String parameter, no variable map is required:
!Sub '${TemplateParameterA} is a ${TemplateParameterB}' !Sub '${AWS::Region}-something'
ImportValue
Can be used as a key in a YAML structure:
... ServiceRole: Fn::ImportValue: ...
or a value:
... EnvironmentVariables: - Name: TARGET_BUCKET Value: Fn::ImportValue: !Sub '${AWS::Region}-BuildBucket'
FindInMap
!FindInMap [ MapName, TopLevelKey, SecondLevelKey ]