AWS Documentation » AWS CloudFormation » User Guide » Template Reference » Intrinsic Function Reference » Ref	« Previous Next »
	Did this page help you? Yes \| No \| Tell us about it...

Ref

The intrinsic function Ref returns the value of the specified parameter or resource.

When you specify a parameter's logical name, it returns the value of the parameter.
When you specify a resource's logical name, it returns a value that you can typically use to refer to that resource.

When you are declaring a resource in a template and you need to specify another template resource by name, you can use the Ref to refer to that other resource. In general, Ref returns the name of the resource. For example, a reference to an AWS::AutoScaling::AutoScalingGroup returns the name of that Auto Scaling group resource.

For some resources, an identifier is returned that has another significant meaning in the context of the resource. An AWS::EC2::EIP resource, for instance, returns the IP address, and an AWS::EC2::Instance returns the instance ID.

At the bottom of this topic, there is a table that lists the values returned for many common resource types. More information about Ref return values for a particular resource or property can be found in the documentation for that resource or property.

Tip

You can also use Ref to add values to Output messages.

Declaration

"Ref" : "logicalName"

Parameters

logicalName: The logical name of the resource or parameter you want to dereference.

Return Value

The value of the MyInputParameter parameter.

Example

The following resource declaration for an Elastic IP address needs the instance ID of an EC2 instance and uses the Ref function to specify the instance ID of the MyEC2Instance resource:

"MyEIP" : {
   "Type" : "AWS::EC2::EIP",
   "Properties" : {
      "InstanceId" : { "Ref" : "MyEC2Instance" }
   }
}

Resource Return Examples

This section lists sample values returned by Ref for particular AWS CloudFormation resources. For more information about Ref return values for a particular resource or property, refer to the documentation for that resource or property.

Resource Type	Reference Value	Example
AWS::AutoScaling::AutoScalingGroup	Name	mystack-myasgroup-NT5EUXTNTXXD
AWS::AutoScaling::LaunchConfiguration	Name	mystack-mylaunchconfig-1DDYF1E3B3I
AWS::AutoScaling::ScalingPolicy	Name	mystack-myaspolicy-1DDYF1E3B3I
AWS::AutoScaling::Trigger	Name	mystack-mytrigger-7GQPDS5YHI5B
AWS::CloudFormation::Stack	Stack ID	arn:aws:cloudformation:us-east-1:803981987763:stack/mystack-myembeddedstack-sggfrhxhum7w/f449b250-b969-11e0-a185-5081d0136786
AWS::CloudFormation::WaitCondition	Name	arn:aws:cloudformation:us-east-1:803981987763:stack/mystack/c325e210-bdf2-11e0-9638-50690880c386/mywaithandle
AWS::CloudFormation::WaitConditionHandle	Wait Condition Signal URL	https://cloudformation-waitcondition-us-east-1.s3.amazonaws.com/arn%3Aaws%3Acloudformation%3Aus-east-1%3A803981987763%3Astack%2Fwaittest%2F054a33d0-bdee-11e0-8816-5081c490a786%2FmyWaitHandle?Expires=1312475488&AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE&Signature=tUsrW3WvWVT46K69zMmgbEkwVGo%3D
AWS::CloudFront::Distribution	Distribution ID	E27LVI50CSW06W
AWS::CloudWatch::Alarm	Name	mystack-myalarm-3AOHFRGOXR5T
AWS::EC2::Volume	Volume ID	vol-3cdd3f56
AWS::EC2::VolumeAttachment	Name	mystack-myvola-ERXHJITXMRLT
AWS::EC2::EIP	Elastic IP Address	192.0.2.0
AWS::EC2::EIPAssociation	Name	mystack-myeipa-1NU3IL8LJ313N
AWS::EC2::Instance	Instance ID	i-636be302
AWS::EC2::SecurityGroup	Name	mystack-mysecuritygroup-QQB406M8FISX
AWS::EC2::SecurityGroupIngress	Name	mysecuritygroupingress
AWS::ElasticLoadBalancing::LoadBalancer	Name	mystack-myelb-1WQN7BJGDB5YQ
AWS::ElasticBeanstalk::Application	Name	mystack-myapplication-FM6BIXY7U8PK
AWS::ElasticBeanstalk::Environment	Name	mystack-myenv-LKGNQSFHO1DB
AWS::IAM::AccessKey	AccessKeyId	AKIAIOSFODNN7EXAMPLE
AWS::IAM::Group	GroupName	mystack-mygroup-1DZETITOWEKVO
AWS::IAM::User	UserName	mystack-myuser-1CCXAFG2H2U4D
AWS::RDS::DBInstance	Name	mystack-mydb-ea5ugmfvuaxg
AWS::RDS::DBSecurityGroup	Name	mystack-mydbsecuritygroup-1k5u5dxjb0nxs
AWS::S3::Bucket	Name	mystack-mys3bucket-1hbsmonr9mytq
AWS::SDB::Domain	Name	mystack-mysdbdomain-IVNAOZTDFVXL
AWS::SNS::Topic	Topic ARN	arn:aws:sns:us-east-1:803981987763:mystack-mytopic-NZJ5JSMVGFIE
AWS::SQS::Queue	Queue URL	https://sqs.us-east-1.amazonaws.com/803981987763/aa4-MyQueue-Z5NOSZO2PZE9
Pseudo Parameter	AWS::Region	us-east-1
Pseudo Parameter	AWS::StackName	MyStack

Document Conventions	« Previous Next »
Terms of Use	Did this page help you? Yes \| No \| Tell us about it...