Reference Architecture: Web Application with multiple public/private services

[cattz]

I'm trying to deploy a pretty straight forward web application architecture with a handful of services (some public, some internal)

And this is a high level overview of the different terraform/terragrunt modules I'm deploying:

I'm trying to split the deployment so that critical and less frequently changing components (such as persistence and networking) are deployed separately.

The issues I'm encountering are:

I'm not finding documentation or examples of a similar approach. Most examples show everything—DB, VPC, ALB, and Fargate service—being deployed in a single Terraform module.
Some resources, like ALB listener rules, IAM roles for CI, and, in some cases, security groups, are difficult to categorize within my modules.
Is anyone else using a similar approach? Any advice or reference documents or code on how to organize these modules?