Bug: AutoPublishAlias won't create new versions if only layer arn is modified.

[DiscreteTom]

Description:

AutoPublishAlias won't create new versions if only layer arn is modified in function's properties.

This will also affect SnapStart since new versions can't be created, users must create the version and modify alias manually.

Steps to reproduce:

1. Deploy an official hello world example (e.g. python3.9 in my case) with AutoPublishAlias enabled. The first deployment will create version 1 for the function.
2. Modify the function's property in template.yaml, add a layer with an ARN. E.g. with lambda web adapter's arn:aws:lambda:${AWS::Region}:753240598075:layer:LambdaAdapterLayerX86:23
3. sam build then sam deploy. The function is updated but no new versions created.
4. Modify the layer's arn, e.g. use an old lambda web adapter layer arn: arn:aws:lambda:${AWS::Region}:753240598075:layer:LambdaAdapterLayerX86:22.
5. sam build then sam deploy. The function is updated but no new versions created.

Observed result:

Add/Modify a layer arn won't create new function versions.

Expected result:

Add/Modify a layer arn should create new function versions.

Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

{
  "version": "1.119.0",
  "system": {
    "python": "3.11.8",
    "os": "Linux-6.1.111-120.187.amzn2023.x86_64-x86_64-with-glibc2.34"
  },
  "additional_dependencies": {
    "docker_engine": "25.0.6",
    "aws_cdk": "2.131.0 (build 92b912d)",
    "terraform": "Not available"
  },
  "available_beta_feature_env_vars": [
    "SAM_CLI_BETA_FEATURES",
    "SAM_CLI_BETA_BUILD_PERFORMANCE",
    "SAM_CLI_BETA_TERRAFORM_SUPPORT",
    "SAM_CLI_BETA_RUST_CARGO_LAMBDA"
  ]
}

Add --debug flag to command you are running

[mbfreder]

Thanks for opening this @DiscreteTom . Setting AutoPublishAliasAllProperties to true creates a new AWS::Lambda::Version when any property in the Lambda function is modified. Please try this and let me know if it works.

[vicheey]

The way SAM know to publish a new version or not is by check the hash of a function. With AutoPublishAlias, only a handful of default properties are used fro the hashing. Layer is not one of this default properties. To solve your current issue, theAutoPublishAliasAllProperties should be used to tell SAM to consider Layer and additional properties when creating a hash.

[DiscreteTom]

Thanks for the response. AutoPublishAliasAllProperties works like a charm.

[github-actions]

⚠️COMMENT VISIBILITY WARNING⚠️

Comments on closed issues are hard for our team to see.
If you need more assistance, please either tag a team member or open a new issue that references this one.
If you wish to keep having a conversation with other community members under this issue feel free to do so.