# ACDL Modules

Reusable building blocks for cloud infrastructure. Each module is
self-documented with a `README.md` following the
[template](README-TEMPLATE.md).

## How the modules work

There are two kinds of module:

- **L1 primitives** — a single cloud resource or a small group of
  related resources (e.g. a VPC with subnets and routing). Each L1 has
  an `interface.json` declaring its inputs and outputs, and a `README.md`
  in plain language.
- **L2 compositions** — a composition that references multiple L1s to
  deploy a complete stack (e.g. an ECS Fargate microservice). **The L2
  composition layer is being redesigned.** The previous implementation
  has been removed; a new mechanism will be designed in a later phase.

The Terraform adapter (`adapters/terraform/adapter.py`) compiles a
module instance to Terraform. Each module's README documents which
Terraform resources it creates.

## L1 primitives

| Module | What it creates | README |
|--------|----------------|--------|
| `l1-s3` | `aws_s3_bucket` — a single S3 bucket | [README](l1/l1-s3/README.md) |
| `l1-vpc` | `aws_vpc` + `aws_subnet` + `aws_route_table` + `aws_internet_gateway` — VPC with subnets and routing | [README](l1/l1-vpc/README.md) |
| `l1-ecs-cluster` | `aws_ecs_cluster` — ECS Fargate cluster | [README](l1/l1-ecs-cluster/README.md) |
| `l1-ecs-service` | `aws_ecs_task_definition` + `aws_ecs_service` — Fargate service with task definition | [README](l1/l1-ecs-service/README.md) |
| `l1-iam-role` | `aws_iam_role` — IAM role with assume-role policy | [README](l1/l1-iam-role/README.md) |
| `l1-alb` | `aws_lb` + `aws_lb_target_group` + `aws_lb_listener` — Application Load Balancer | [README](l1/l1-alb/README.md) |
| `l1-ecr` | `aws_ecr_repository` — ECR container image repository | [README](l1/l1-ecr/README.md) |

## L2 compositions

| Module | What it references | README |
|--------|--------------------|--------|
| `l2-microservice` | 6 L1s (vpc, cluster, ecr, iam-role, alb, ecs-service) — **under redesign** | [README](l2/l2-microservice/README.md) |
| `l2-static-asset` | 1 L1 (s3) — **under redesign** | [README](l2/l2-static-asset/README.md) |

## Registry

Module versions are tracked in `registry.json`. Only L1 entries are
active; L2 entries have been pruned pending the composition redesign.

## Template

New modules should use [README-TEMPLATE.md](README-TEMPLATE.md) as
their starting point.