add source code hash to lambda layer

[pedro-emidio]

AFT Version

1.13.2

Open issue

#507

Description

I implemented AFT a few months ago when it was not yet compatible with GitLab. Recently, I noticed that starting with version 1.13.2, the module now supports GitLab integration.

While updating the AFT module to use GitLab, I encountered the same issue: when files in the bucket aft-customizations-pipeline-your_account_id were updated, Terraform did not detect the changes to generate a new layer version. This caused a mismatch between the bucket and the code used by the layer.

The solution I implemented was to add the source_code_hash attribute to the aws_lambda_layer_version resource, setting it to use the etag attribute from the aws_s3_bucket_object data source. This ensures that whenever the object in the bucket is updated, Terraform detects the change and automatically publishes a new layer version.

Reference links

• https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/lambda_layer_version#source_code_hash-1
• https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/s3_bucket_object#etag-1