AWS Proton parameters

You can define and use parameters in your infrastructure as code (IaC) files to make them flexible and re-usable. You read a parameter value in your IaC files by referring to the parameter's name in the AWS Proton parameter namespace. AWS Proton injects parameter values into the rendered IaC files that it generates during resource provisioning. To process AWS CloudFormation IaC parameters, AWS Proton uses Jinja. To process Terraform IaC parameters, AWS Proton generates a Terraform parameter value file and relies on the parametrization ability built into HCL.

With CodeBuild provisioning, AWS Proton generates an input file that your code can import. The file is a JSON or HCL file, depending on a property in your template's manifest. For more information, see CodeBuild provisioning parameter details and examples.

You can refer to parameters in your environment, service, and component IaC files or provisioning code with the following requirements:

• The length of each parameter name doesn't exceed 100 characters.

• The length of the parameter namespace and resource name combined doesn't exceed the character limit for the resource name.

AWS Proton provisioning fails if these quotas are exceeded.

Parameter types

The following parameter types are available to you for reference in AWS Proton IaC files:

Input parameter

Environments and service instances can take input parameters that you define in a schema file that you associate with the environment or service template. You can refer to a resource's input parameters in the resource's IaC file. Component IaC files can refer to input parameters of the service instance that the component is attached to.

AWS Proton checks input parameter names against your schema file, and matches them with the parameters that are referenced in your IaC files to inject the input values that you provide in a spec file during resource provisioning.

Output parameter

You can define outputs in any of your IaC files. An output can be, for example, a name, ID, or ARN of one of the resources that the template provisions, or it can be a way to pass through one of the template's inputs. You can refer to these outputs in IaC files of other resources.

In CloudFormation IaC files,define output parameters in the Outputs: block. In a Terraform IaC file, define each output parameter using an output statement.

Resource parameter

AWS Proton automatically creates AWS Proton resource parameters. These parameters expose properties of the AWS Proton resource object. An example of a resource parameter is environment.name.

Using AWS Proton parameters in your IaC files

To read a parameter value in an IaC file, you refer to the parameter's name in the AWS Proton parameter namespace. For AWS CloudFormation IaC files, you use Jinja syntax and surround the parameter with pairs of curly braces and quotation marks.

The following table shows the reference syntax for each supported template language, with an example.

Template language	Syntax	Example: environment input named "VPC"
CloudFormation	"{{ parameter-name }}"	"{{ environment.inputs.VPC }}"
Terraform	var.parameter-name	var.environment.inputs.VPC Generated Terraform variable definitions

Note

If you use CloudFormation dynamic parameters in your IaC file, you must escape them to prevent Jinja misinterpretation errors. For more information, see Troubleshooting AWS Proton

The following table lists namespace names for all AWS Proton resource parameters. Each template file type can use a different subset of the parameter namespace.

Template file	Parameter type	Parameter name	Description
Environment	resource	environment.name	Environment name
	input	environment.inputs.input-name	Schema-defined environment inputs
Service	resource	environment.name environment.account_id	Environment name and AWS account ID
	output	environment.outputs.output-name	Environment IaC file outputs
	resource	service.branch_name service.name service.repository_connection_arn service.repository_id	Service name and code repository
	resource	service_instance.name	Service instance name
	input	service_instance.inputs.input-name	Schema-defined service instance inputs
	resource	service_instance.components.default.name	Attached default component name
	output	service_instance.components.default.outputs.output-name	Attached default component IaC file outputs
Pipeline	resource	service_instance.environment.name service_instance.environment.account_id	Service instance environment name and AWS account ID
	output	service_instance.environment.outputs.output-name	Service instance environment IaC file outputs
	input	pipeline.inputs.input-name	Schema-defined pipeline inputs
	resource	service.branch_name service.name service.repository_connection_arn service.repository_id	Service name and code repository
	input	service_instance.inputs.input-name	Schema-defined service instance inputs
	collection	{% for service_instance in service_instances %}...{% endfor %}	A collection of service instances that you can loop through
Component	resource	environment.name environment.account_id	Environment name and AWS account account ID
	output	environment.outputs.output-name	Environment IaC file outputs
	resource	service.branch_name service.name service.repository_connection_arn service.repository_id	Service name and code repository (attached components)
	resource	service_instance.name	Service instance name (attached components)
	input	service_instance.inputs.input-name	Schema-defined service instance inputs (attached components)
	resource	component.name	Component name

For more information and examples, see the subtopics about parameters in IaC template files for different resource types and template languages.

Topics

• Environment CloudFormation IaC file parameter details and examples
• Service CloudFormation IaC file parameter details and examples
• Component CloudFormation IaC file parameter details and examples
• Parameter filters for CloudFormation IaC files
• CodeBuild provisioning parameter details and examples
• Terraform infrastructure as code (IaC) file parameter details and examples