Parameter

The Parameter declaration specifies a value that is supplied at module deployment time either by the LambdaSharp CLI or a parent module. Module parameters can be modified subsequently by updating the CloudFormation stack in the AWS console.

Syntax

Parameter: String
Description: String
Section: String
Label: String
Scope: ScopeDefinition
NoEcho: Boolean
Default: String
AllowedValues:
  - String
AllowedPattern: String
ConstraintDescription: String
MaxLength: Int
MaxValue: Int
MinLength: Int
MinValue: Int
Pragmas:
  - PragmaDefinition
Type: String
Allow: AllowDefinition
DefaultAttribute: String
Properties:
  ResourceProperties
DeletionPolicy: String
EncryptionContext:
  Key-Value Mapping

Properties

Allow

The Allow attribute can be either a comma-separated, single string value, or a list of string values. String values that contain a colon (:) are interpreted as IAM permission and used as is (e.g. dynamodb:GetItem, s3:GetObject*, etc.). Otherwise, the value is interpreted as a LambdaSharp shorthand (see LambdaSharp Shorthand by Resource Type). Both notations can be used simultaneously within a single Allow section. Duplicate IAM permissions, after LambdaSharp shorthand resolution, are removed.

Required: No

Type: Either String or List of String

AllowedPattern

The AllowedPattern attribute specifies a regular expression that represents the patterns to allow for String types.

Required: No

Type: String

AllowedValues

The AllowedValues attribute specifies a list of allowed values for the parameter.

Required: No

Type: List of String

ConstraintDescription

The ConstraintDescription is used to explain a constraint when the constraint is violated.

Required: No

Type: String

Default

The Default attribute specifies a value to use when no value is provided for a module deployment. If the parameter defines value constraints, the default value must adhere to those constraints.

Required: No

Type: String

DefaultAttribute

The DefaultAttribute attribute specifies the resource attribute to use when exporting the resource from the module or to a Lambda function. By default, the LambdaSharp CLI automatically selects the Arn attribute when available. Otherwise, it uses the return value of a !Ref expressions. This behavior can be overwritten by specifying a DefaultAttribute attribute.

Required: No

Type: String

DeletionPolicy

The DeletionPolicy attribute specifies what to do with the resource when the stack is deleted. The value must be one of: Retain or Snapshot. The DeletionPolicy attribute can only be used on conjunction with the Properties section.

Required: No

Type: String

Description

The Description attribute specifies the parameter description. The description is shown in the AWS Console when creating or updating the CloudFormation stack.

Required: No

Type: String

EncryptionContext

The EncryptionContext section is an optional mapping of key-value pairs used for decrypting a variable of type Secret. For all other types, specifying EncryptionContext will produce a compilation error.

Required: No

Type: Key-Value Pair Mapping

Label

The Label specifies a human readable label for the parameter. This label is used instead of the parameter name by the AWS Console when updating a CloudFormation stack.

Required: No

Type: String

MaxLength

The MaxLength attribute specifies an integer value that determines the largest number of characters you want to allow for String types.

Required: No

Type: Int

MaxValue

The MaxValue attribute specifies a numeric value that determines the largest numeric value you want to allow for Number types.

Required: No

Type: Int

MinLength

The MinLength attribute specifies an integer value that determines the smallest number of characters you want to allow for String types.

Required: No

Type: Int

MinValue

The MinValue attribute specifies a numeric value that determines the smallest numeric value you want to allow for Number types.

Required: No

Type: Int

NoEcho

The NoEcho attribute specifies whether to mask the parameter value when a call is made that describes the stack. If you set the value to true, the parameter value is masked with asterisks (*****).

Required: No

Type: String

Parameter

The Parameter attribute specifies the parameter name. The name must start with a letter and followed only by letters or digits. Punctuation marks are not allowed. All names are case-sensitive.

Required: Yes

Type: String

Pragmas

The Pragmas section specifies directives that change the default compiler behavior.

Required: No

Type: List of Pragma Definition

Properties

The Properties section indicates the parameter represents a resource that can be specified at stack creation/update time. When omitted, the parameter is treated as a new resource that is instantiated.

The Properties section specifies additional options that can be specified for a managed resource. This section is copied verbatim into the CloudFormation template and can use CloudFormation intrinsic functions (e.g. !Ref, !Join, !Sub, etc.) for referencing other resources.

The Properties section cannot be specified for referenced resources. For a list of all additional options, see AWS Resource Types Reference.

Required: No

Type: Map

Scope

The Scope attribute specifies which functions need to have access to this item. The Scope attribute can be a comma-separated list or a YAML list of function names. If all functions need the item, then all can be used as a wildcard. In addition, public can be used to export the item from the module. Alternatively, stack can be used to make the item available only in a nested stack.

Required: No

Type: Comma-delimited String or List of String

Section

The Section attribute specifies a title for grouping related module inputs together. The AWS Console uses the title for laying out module inputs into sections. The order of the sections and the order of the module inputs in the section is determined by the order in which they occur in the module definition.

Required: No

Type: String

Type

The Type attribute specifies the data type for the parameter. When omitted, the type is assumed to be String.

Required: No

Type: String

The following parameter types are supported by CloudFormation. When using other AWS resource types, LambdaSharp automatically declares them as String type.

String

A literal string.

Secret

An encrypted string.

Number

An integer or float. The parameter value is validated as a number. However, when you use the parameter elsewhere in your module (for example, by using the !Ref function), the parameter value becomes a string.

List<Number>

An array of integers or floats that are separated by commas. The parameter value is validated as numbers. However, when you use the parameter elsewhere in your module (for example, by using the !Ref function), the parameter value becomes a list of strings.

CommaDelimitedList

An array of literal strings that are separated by commas. The total number of strings should be one more than the total number of commas. Also, each member string is space trimmed.

AWS-Specific Parameter Types

AWS values such as Amazon EC2 key pair names and VPC IDs. For more information, see AWS-Specific Parameter Types.

SSM Parameter Types

Parameters that correspond to existing parameters in Systems Manager Parameter Store. You specify a Systems Manager parameter key as the value of the SSM parameter, and AWS CloudFormation fetches the latest value from Parameter Store to use for the stack. For more information, see SSM Parameter Types.

Examples

A parameter

- Parameter: MyParameter
  Description: A module parameter

An optional parameter

- Parameter: MyParameter
  Description: A module parameter
  Default: no value provided

A parameter with associated IAM permissions

- Parameter: MyTopic
  Description: A topic ARN
  Type: AWS::SNS::Topic
  Allow: Publish

An optional parameter that generates a resource on default value

- Parameter: MyTopic
  Description: A topic ARN
  Type: AWS::SNS::Topic
  Allow: Publish
  Properties:
    DisplayName: New topic display name