AWS CloudFormation Concepts Condition Functions: Difference between revisions

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=Internal=
=Internal=


* [[AWS CloudFormation Concepts#Conditional_Functions|AWS CloudFormation Concepts]]
* [[AWS_CloudFormation_Concepts#Condition_Functions|AWS CloudFormation Concepts]]
* [[AWS CloudFormation Concepts Intrinsic Functions|Intrinsic Functions]]
* [[AWS CloudFormation Concepts Intrinsic Functions|Intrinsic Functions]]
=Overview=
As it is the case for [[AWS_CloudFormation_Concepts_Intrinsic_Functions#Overview|intrinsic functions]], condition functions have a full function name, and a short form. For more details see:
{{Internal|AWS_CloudFormation_Concepts_Intrinsic_Functions#Overview|Intrinsic Functions - Overview}}
=Fn::If: !If=
<font color=darkgray>
Fn::If: function can be used to conditionally specify a property.
Fn::If is only supported in the metadata attribute, update policy attribute, and property values in the Resources section and Outputs sections of a template.
</font>
=Fn::And: !And=
=Fn::Equals: !Equals=
!Equals ['something', !Ref SomethingElse]
=Fn::Not: !Not=
For YAML syntax reasons, it's best to leave spaces around [ and ].
Conditions:
  SomeCondition:
    Fn::Not: [ !Equals [ 'blue', !Ref SomeParameter ] ]
Conditions:
  SomeCondition:
    !Not  [ !Equals  [ 'blue', !Ref SomeParameter ] ]
=Fn::Or: !Or=
=Expressions=
Expressions can use [[AWS_CloudFormation_Concepts#Pseudo-Parameters|pseudo-parameters]], [[AWS_CloudFormation_Concepts#Input_Parameters_.28Template_Parameters.29|template input parameters]] and [[AWS_CloudFormation_Concepts#Mappings|mappings]]. Expressions are useful when declaring [[AWS_CloudFormation_Concepts#Conditions|Conditions]]. Other conditions can be referenced within conditions.

Latest revision as of 19:12, 18 April 2019

External

Condition Functions

Internal

Overview

As it is the case for intrinsic functions, condition functions have a full function name, and a short form. For more details see:

Intrinsic Functions - Overview

Fn::If: !If

Fn::If: function can be used to conditionally specify a property.

Fn::If is only supported in the metadata attribute, update policy attribute, and property values in the Resources section and Outputs sections of a template.

Fn::And: !And

Fn::Equals: !Equals

!Equals ['something', !Ref SomethingElse]

Fn::Not: !Not

For YAML syntax reasons, it's best to leave spaces around [ and ].

Conditions:
  SomeCondition:
    Fn::Not: [ !Equals [ 'blue', !Ref SomeParameter ] ]
Conditions:
  SomeCondition:
   !Not  [ !Equals  [ 'blue', !Ref SomeParameter ] ]

Fn::Or: !Or

Expressions

Expressions can use pseudo-parameters, template input parameters and mappings. Expressions are useful when declaring Conditions. Other conditions can be referenced within conditions.