AWS CloudFormation Concepts Condition Functions

External

Condition Functions

Internal

• AWS CloudFormation Concepts
• Intrinsic Functions

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::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 ] ]

Expressions

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