Intrinsic functions in CloudFormation

CloudFormation is a very popular and widely used service of AWS. it is an infrastructure as a code service. we declare all the resources in the cloud formation template in the form of JSON or YAML format.

Intrinsic functions in CloudFormation are built-in functions that help us assign values to attributes at runtime. Here we will discuss a few intrinsic functions.

Ref

The Ref function returns the value of attributes or resources.

Example

MyEIP:
Type: "AWS::EC2::EIP"
Properties:
InstanceId: !Ref MyEC2Instance

Fn::GetAtt

The Fn::GetAtt function returns an attribute's value from a resource in the template.

Syntax

Fn::GetAtt: [ logicalNameOfResource, attributeName ]
#Example
!GetAtt myELB.DNSName

Fn::FindInMap

We use Fn::FindInMap to return a named value from a specific key.

Syntax

Fn::FindInMap: [ MapName, TopLevelKey, SecondLevelKey ]

#Syntax for the short form

!FindInMap [ MapName, TopLevelKey, SecondLevelKey ]

Fn::ImportValue

We use Fn::ImportValue when we import the value of an output exported by another stack.

Syntax

Fn::ImportValue: sharedValueToImport

Alternatively, you can use the short form

!ImportValue sharedValueToImport