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AWS CloudFormation
User Guide (API Version 2010-05-15)

Outputs

The optional Outputs section declares output values that you can import into other stacks (to create cross-stack references), return in response (to describe stack calls), or view on the AWS CloudFormation console. For example, you can output the S3 bucket name for a stack to make the bucket easier to find.

Syntax

The Outputs section consists of the key name Outputs, followed by a space and a single colon. You can declare a maximum of 60 outputs in a template.

The following example demonstrates the structure of the Outputs section.

JSON

Use braces to enclose all output declarations. Delimit multiple outputs with commas.

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"Outputs" : { "Logical ID" : { "Description" : "Information about the value", "Value" : "Value to return", "Export" : { "Name" : "Value to export" } } }

YAML

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Outputs: Logical ID: Description: Information about the value Value: Value to return Export: Name: Value to export

Output Fields

The Outputs section can include the following fields.

Logical ID

An identifier for the current output. The logical ID must be alphanumeric (a-z, A-Z, 0-9) and unique within the template.

Description (optional)

A String type that describes the output value. The description can be a maximum of 4 K in length.

Value (required)

The value of the property returned by the aws cloudformation describe-stacks command. The value of an output can include literals, parameter references, pseudo-parameters, a mapping value, or intrinsic functions.

Export (optional)

The name of the resource output to be exported for a cross-stack reference.

Note

The following restrictions apply to cross-stack references:

  • For each AWS account, Export names must be unique within a region.

  • You can't create cross-stack references across regions. You can use the intrinsic function Fn::ImportValue to import only values that have been exported within the same region.

  • For outputs, the value of the Name property of an Export can't use Ref or GetAtt functions that depend on a resource.

    Similarly, the ImportValue function can't include Ref or GetAtt functions that depend on a resource.

  • You can't delete a stack if another stack references one of its outputs.

  • You can't modify or remove an output value that is referenced by another stack.

You can use intrinsic functions to customize the Name value of an export. The following examples use the Fn::Join function.

JSON

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"Export" : { "Name" : { "Fn::Join" : [ ":", [ { "Ref" : "AWS::StackName" }, "AccountVPC" ] ] } }

YAML

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Export: Name: !Join [ ":", [ !Ref "AWS::StackName", AccountVPC ] ]

To associate a condition with an output, define the condition in the Conditions section of the template.

Examples

The following examples illustrate how stack output works.

Stack Output

In the following example, the output named BackupLoadBalancerDNSName returns the DNS name for the resource with the logical ID BackupLoadBalancer only when the CreateProdResources condition is true. (The second output shows how to specify multiple outputs.)

JSON

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"Outputs" : { "BackupLoadBalancerDNSName" : { "Description": "The DNSName of the backup load balancer", "Value" : { "Fn::GetAtt" : [ "BackupLoadBalancer", "DNSName" ]}, "Condition" : "CreateProdResources" }, "InstanceID" : { "Description": "The Instance ID", "Value" : { "Ref" : "EC2Instance" } } }

YAML

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Outputs: BackupLoadBalancerDNSName: Description: The DNSName of the backup load balancer Value: !GetAtt BackupLoadBalancer.DNSName Condition: CreateProdResources InstanceID: Description: The Instance ID Value: !Ref EC2Instance

Cross-Stack Output

In the following examples, the output named StackVPC returns the ID of a VPC, and then exports the value for cross-stack referencing with the name VPCID appended to the stack's name.

JSON

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"Outputs" : { "StackVPC" : { "Description" : "The ID of the VPC", "Value" : { "Ref" : "MyVPC" }, "Export" : { "Name" : {"Fn::Sub": "${AWS::StackName}-VPCID" } } } }

YAML

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Outputs: StackVPC: Description: The ID of the VPC Value: !Ref MyVPC Export: Name: !Sub "${AWS::StackName}-VPCID"

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