End of support notice: On October 7, 2026, AWS will end support for AWS Proton. After October 7, 2026, you will no longer be able to access the AWS Proton console or AWS Proton resources. Your deployed infrastructure will remain intact. For more information, see [AWS Proton Service Deprecation and Migration Guide](https://docs.aws.amazon.com/proton/latest/userguide/proton-end-of-support.html).

# Service CloudFormation IaC file parameter details and examples
<a name="svc-parameters"></a>

You can define and reference parameters in your service and pipeline infrastructure as code (IaC) files. For a detailed description of AWS Proton parameters, parameter types, the parameter namespace, and how to use parameters in your IaC files, see [AWS Proton parameters](parameters.md).

## Define service parameters
<a name="svc-parameters.define"></a>

You can define both input and output parameters for service IaC files.
+ **Input parameters** – Define service instance input parameters in your [schema file](ag-schema.md).

  The following list includes examples of service input parameters for typical use cases.
  + Port
  + Task size
  + Image
  + Desired count
  + Docker file
  + Unit test command

  You provide values for input parameters when you [create a service](ag-create-svc.md):
  + Use the console to fill out a schema-based form that AWS Proton provides.
  + Use the CLI to provide a spec that includes the values.
+ **Output parameters** – Define service instance outputs in your service IaC files. You can then refer to these outputs in IaC files of other resources.

## Read parameter values in service IaC files
<a name="svc-parameters.refer"></a>

You can read parameters related to the service and to other resources in service IaC files. You read a parameter value by referencing the parameter's name in the AWS Proton parameter namespace.
+ **Input parameters** – Read a service instance input value by referencing `service_instance.inputs.input-name`.
+ **Resource parameters** – Read AWS Proton resource parameters by referencing names such as `service.name`, `service_instance.name`, and `environment.name`.
+ **Output parameters** – Read outputs of other resources by referencing `environment.outputs.output-name` or `service_instance.components.default.outputs.output-name`.

## Example service IaC file with parameters
<a name="svc-parameters.example"></a>

The following example is a snippet from a service CloudFormation IaC file. The `environment.outputs.` namespace refers to outputs from the environment IaC file. The `service_instance.inputs.` namespace refers to service instance input parameters. The `service_instance.name` property refers to an AWS Proton resource parameter.

```
Resources:
  StoreServiceInstanceInputValue:
    Type: AWS::SSM::Parameter
    Properties:
      Type: String
      Value: "{{ service.name }} {{ service_instance.name }} {{ service_instance.inputs.my_sample_service_instance_required_input }} {{ service_instance.inputs.my_sample_service_instance_optional_input }} {{ environment.outputs.MySampleInputValue }} {{ environment.outputs.MyOtherSampleInputValue }}"
              #  resource parameter references               # input parameter references                                                                                                                    # output references to an environment infrastructure as code file
Outputs:
  MyServiceInstanceParameter:                                                         # output definition
    Value: !Ref StoreServiceInstanceInputValue 
  MyServiceInstanceRequiredInputValue:                                                # output definition
    Value: "{{ service_instance.inputs.my_sample_service_instance_required_input }}"  # input parameter reference
  MyServiceInstanceOptionalInputValue:                                                # output definition
    Value: "{{ service_instance.inputs.my_sample_service_instance_optional_input }}"  # input parameter reference
  MyServiceInstancesEnvironmentSampleOutputValue:                                     # output definition
    Value: "{{ environment.outputs.MySampleInputValue }}"                             # output reference to an environment IaC file
  MyServiceInstancesEnvironmentOtherSampleOutputValue:                                # output definition
    Value: "{{ environment.outputs.MyOtherSampleInputValue }}"                        # output reference to an environment IaC file
```