!If not working on Serverless:Function handler

[des-psl]

Description

I am trying to have a conditional (!If) on my lambda handler property to execute different logics depending of an env var

Steps to reproduce

AWSTemplateFormatVersion: "2010-09-09"
Transform: AWS::Serverless-2016-10-31

Parameters:
  NewRelicEnabled:
    Type: String
    Description: Enable New Relic integration.
    Default: true

Conditions:
  IsNewRelicEnabled: !Equals [!Ref NewRelicEnabled, true]

Globals:
  Function:
    Architectures:
      - arm64
    Handler: !If [IsNewRelicEnabled, test1.handler, test2.handler]

Resources:
  ImportFunction:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: import-function
      CodeUri: application/functions/import/
    Metadata:
      BuildMethod: esbuild
      BuildProperties:
        Format: esm
        Minify: true
        OutExtension:
          - .js=.mjs
        Target: "es2020"
        Sourcemap: true
        EntryPoints:
          - index.ts
        Banner:
          - js=import { createRequire } from 'module'; const require = createRequire(import.meta.url);
        External:
          - application/node_modules

 Outputs:
  Condition:
    Description: asdf
    Value: !If [IsNewRelicEnabled, test1.handler, test2.handler]

Observed result

Global handlers variable is resolving to its false value (test2.handler), but at the Outputs, Condition is resolving to true (test1.handler)

Expected result

Global handlers and Output Condition should both resolving to true (test1.handler)

Additional environment details

1. OS: Mac
2. If using the SAM CLI, sam --version:
3. AWS region: eu-east-1

[xazhao]

Hello @des-psl , thanks for raising the issue.

As mentioned in #2533 SAM Transform does not support intrinsic functions for handler. So to make sure that SAM handles the created resources as you expect, we recommend you to use the AWS::LanguageExtensions Transform, and add it before SAM Transform so SAM receives the template after got processed, and intrinsic function got replaced with the actual values.

You can update your template, and replace

Transform: AWS::Serverless-2016-10-31

with

Transform:
  - AWS::LanguageExtensions
  - AWS::Serverless-2016-10-31

[des-psl]

@xazhao I tried your solution but still not working:

AWSTemplateFormatVersion: "2010-09-09"
Transform:
  - AWS::LanguageExtensions
  - AWS::Serverless-2016-10-31

[moelasmar]

Hi @des-psl,
Looking to your example, I think the problem is you defined the intrinsic function in the Globals section, and as it is not part of The CFN template anatomy (doc), so AWS::LanguageExtensions will not resolve the intrinsic functions defined in it. And since SAM Transform could not process the intrinsic functions, you are facing this problem.

The recommendation is not to use any intrinsic functions in the Globals section, and if you want to use intrinsic functions, you can use it in the resource itself.

[xazhao]

Closing the issue. Feel free to reopen it if you have other questions.

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