# 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:

- **Primitives** — a single cloud resource or a small group of
  related resources (e.g. a VPC with subnets and routing). Each primitive
  has an `interface.json` declaring its inputs and outputs, and a
  `README.md` in plain language.
- **Modules** — a pattern that references multiple primitives to
  deploy a complete stack (e.g. an ECS Fargate microservice). Each module
  has a `composition.json` declaring its children and wires.

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

## Primitives

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

## Modules

| Module | What it references | README |
|--------|--------------------|--------|
| `microservice` | 6 primitives (vpc, cluster, ecr, iam-role, alb, ecs-service) | [README](l2/microservice/README.md) |
| `static-asset` | 1 primitive (s3) | [README](l2/static-asset/README.md) |

## Registry

Module versions are tracked in `registry.json`. Both primitives and
modules are registered.

## Template

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

## Module patterns (roadmap)

The current `composition.json` mechanism is a thin pattern layer. A future
redesign will let a consumer dynamically create a module directly from the
contract file (an agentic "composition" flow). That is on the roadmap, not
implemented today.