AWSTemplateFormatVersion: 2010-09-09
Transform: 'AWS::Serverless-2016-10-31'
Description: A Lambda function that uses a Lambda Layer to retrieve configuration values.
# The parameter values for AppName, ParameterPath, and LayerArn are received from the parent stack.
Parameters:
  AppName:
    Description: Name of application.
    Type: String
  ParameterPath:
    Description: Parameter path without lagging forward slash (/).
    Type: String
    MinLength: 1
    MaxLength: 950
    AllowedPattern: ^[a-zA-Z0-9_.-/]*$
  LayerArn:
    Description: Arn of Lambda Layer.
    Type: String
Resources:
  Function:
    Type: 'AWS::Serverless::Function'
    Properties:
      FunctionName: !Sub ${AppName}-function
      Runtime: nodejs14.x
      CodeUri: ./src
      Handler: app.handler
      FunctionUrlConfig:
        AuthType: NONE
      Architectures:
        - arm64
      Environment:
        Variables:
          ParameterPath: !Ref ParameterPath
      Policies:
        - Statement:
          - Effect: Allow
            Action:
              - ssm:GetParameter*
            Resource: !Sub arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/*
      Layers:
        - !Ref LayerArn
# Output from this nested stack is used in the output section of the parent stack.
Outputs:
  FunctionName:
    Description: Name of Lambda function.
    Value: !Ref Function
  # When creating function URLs using AWS SAM, a resource name is auto-generated with the following syntax: {Function-Resource-Name}Url
  # If 'Function' is the function resource name in the SAM template, the function URL resource name will be 'FunctionUrl'.
  FunctionUrl:
    Description: Url of Lambda function.
    Value: !GetAtt FunctionUrl.FunctionUrl