Function

The Function declaration specifies a Lambda function for deployment. Each declaration is compiled and uploaded as part of the deployment process. The deployed Lambda function is prefixed with ${Deployment::TierPrefix} to uniquely distinguish is from other functions.

Use the lash new app command to add the Function declaration with a pre-configured project to your module.

Syntax

Function: String
Description: String
Scope: ScopeDefinition
If: String or Expression
Memory: Int
Timeout: Int
Project: String
Handler: String
Runtime: String
Language: String
Pragmas:
  - PragmaDefinition
Environment:
  String: String or Expression
Properties:
  ResourceProperties
Sources:
  - SourceDefinition
DependsOn:
  - String

Properties

DependsOn

The DependsOn attribute identifies items that must be created prior. For additional information, see CloudFormation DependsOn Attribute.

Type: List of String

Description

The Description attribute specifies the description of the Lambda function.

Required: No

Type: String

Environment

The Environment sections specifies key-value pairs that correspond to custom Lambda environment variables which can be retrieved by the Lambda function during initialization. The attribute can be a plaintext value or a CloudFormation expression (e.g. !Ref MyResource).

Required: No

Type: Map of key-value pair Expressions

Function

The Function attribute specifies the item name for the Lambda function.

Required: Yes

Type: String

Handler

The Handler attribute specifies the fully qualified method reference to the Lambda function handler.

Required: Conditional. By default, the .NET Core method reference is expected to be ${Module::Name}.${FunctionName}::${Namespace}.Function::FunctionHandlerAsync where ${Namespace} is determined by inspecting the <RootNamespace> element of the .NET Core project file. If the Lambda function handler is not called FunctionHandlerAsync, or the class implemented it is not called Function, or the <RootNamespace> is not specified in the .NET Core project file, the Handler attribute must be specified. Otherwise, it can be omitted. For javascript functions, the Handler is set to index.handler by default.

Type: String

If

The If attribute specifies a condition that must be met for the Lambda function to be included in the deployment. The condition can either the name of a Condition item or a logical expression.

Required: No.

Type: String or Expression

Memory

The Memory attribute specifies the memory limit for the lambda function. The value must be in the range of 128 MB up to 3008 MB, in 64 MB increments.

Required: Yes

Type: Int

Pragmas

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

Required: No

Type: List of Pragma Definition

Project

The Project attribute specifies the relative path of the function project file or its folder.

Required: Conditional. By default, the .NET Core project file is expected to be located in a sub-folder of the module definition. The name of the sub-folder and project file are expected to match the function name. If that is not the case, then the Project attribute must be specified. Otherwise, it can be omitted.

Type: String

Properties

The Properties section specifies additional options that can be specified for a Lambda function (see AWS::Lambda::Function CloudFormation type). 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.

Required: No

Type: Map

Runtime

The Runtime attribute specifies the Lambda runtime to use to run the function.

Required: Conditional. By default, the runtime is determined by inspecting the function sub-folder. If the runtime cannot be determined automatically, then it must be specified. Otherwise, it can be omitted.

Type: String

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

Sources

The Sources section specifies zero or more source definitions the Lambda function expects to be invoked by. Each source automatically grants the Lambda invocation permission to the invoking service.

Required: No

Type: List of Source Definition

Timeout

The Timeout attribute specifies the execution time limit in seconds. The maximum value is 900 seconds (15 minutes).

Required: Yes

Type: Int

Examples

A vanilla Lambda function

- Function: MyFunction
  Memory: 128
  Timeout: 15

A Lambda function with an SNS event source

- Function: MyFunction
  Memory: 128
  Timeout: 15
  Sources:
    - Topic: MySnsTopic

A conditional Lambda function

- Condition: IsFunctionWanted
  Value: !Equals [ !Ref WantFunctionParameter, "yes" ]

- Function: MyFunction
  If: IsFunctionWanted
  Memory: 128
  Timeout: 15

The above definitions can be expressed more concisely if the Condition item never used by anywhere else.

- Function: MyFunction
  If: !Equals [ !Ref WantFunctionParameter, "yes" ]
  Memory: 128
  Timeout: 15

A Lambda function with properties

- Function: MyFunction
  Memory: 128
  Timeout: 15
  Properties:
    ReservedConcurrentExecutions: 1
    VpcConfig:
      SecurityGroupIds: !Split [ ",", !Ref SecurityGroupIds ]
      SubnetIds: !Split [ ",", !Ref SubnetIds ]