/aws-sst-development

name: aws-sst-development
description: "SST v4 (Ion) expert for managing AWS resources as code with the Pulumi-backed framework."
risk: critical
source: https://github.com/zxkane/aws-skills/tree/main/plugins/aws-iac/skills/aws-sst-development
source_repo: zxkane/aws-skills
source_type: community
date_added: 2026-07-01
license: MIT
license_source: https://github.com/zxkane/aws-skills/blob/main/LICENSE

SST v4 for AWS

When to Use

Use this skill when you need sST v4 (Ion) expert for managing AWS resources as code with the Pulumi-backed framework. Use when writing or editing sst.config.ts, building infra/ modules (sst.aws.Function/Bucket/Dynamo/Cron/Service/Router, sst.Secret, sst.Linkable, raw aws.* Pulumi resources), wiring resource links,...

SST v4 (the "Ion" engine) is a Pulumi-backed IaC framework: you describe AWS resources in TypeScript and SST/Pulumi reconciles them into your account. It gives you high-level `sst.aws.*` components (Function, Bucket, Dynamo, Cron, Service, …) that expand into many underlying resources, plus an escape hatch to *any* raw Pulumi `aws.*` resource for the long tail. This skill encodes a production-proven way to author, link, test, deploy, and troubleshoot SST stacks on AWS — distilled from real multi-stack projects that have paid for each lesson with a prod incident.

**SST and Pulumi are third-party — verify current syntax with Context7** (`resolve-library-id` → `query-docs` for `sst` or `pulumi-aws`) when you're unsure about a component's options. Verify AWS-side facts (service limits, model IDs, IAM action names, region availability) with the AWS docs MCP, never from memory. The patterns here are the *how*; the docs are the *what*.

When you're invoked

Figure out which mode you're in and jump to the right reference:

| Situation | Go to | |-----------|-------| | New project, or adding a resource/module to an existing SST app | **Author** → `references/authoring.md` | | Wiring one module's output into another (links, SSM, IAM scope) | **Author** → `references/authoring.md` § Sharing | | Writing tests for infra so changes don't silently break | **Test** → `references/testing.md` | | Running a deploy, or a deploy just failed | **Deploy/Operate** → `references/deploy-and-troubleshoot.md` | | Migrating a resource between Pulumi types, renaming a physical name | **Deploy/Operate** → `references/deploy-and-troubleshoot.md` § Migrations |

Always read the relevant reference before editing — they carry the *why* behind each rule, which matters more than the rule itself.

Orientation: read the repo before you touch it

SST projects are conventional but not identical. Before editing, build a quick map so your change matches the house style instead of fighting it:

1. **`sst.config.ts`** — the app name, `home`, providers/region, `defaultTags`, any global `$transform` (Node runtime pin, bundle fixups), and the order in which `run()` imports `infra/` modules. The import order *is* the dependency order; respect it. 2. **`infra/`** — one file per domain (storage, functions, api, observability…). This is where resources are declared. Check for an `infra/CLAUDE.md` — these projects keep IaC-specific rules there, and it's the single most valuable file to read first. 3. **`infra/tests/`** — source-level Vitest assertions that pin resource invariants. If they exist, your change must keep them green and probably needs a new assertion. 4. **`package.json` / `.nvmrc`** — package manager (npm vs pnpm), Node version, and the `sst`/`pulumi` versions actually installed.

Run `npx sst version` to confirm you're on v4/Ion (the `$config` + `.sst/platform/` signature). v2/v3 ("SST Classic", CDK-based) is a different framework — these patterns don't apply there.

The conventions, and which are universal vs tunable

The projects this skill is built from share a deliberate house style. Some of it is **universal** (true for any SST v4 + AWS project — apply it everywhere); some is **project-specific** (a sensible default these projects chose — adopt it for consistency, but recognize a project may differ).

**Universal — these principles hold for any SST v4 + AWS project:**

• **Control the Node runtime deliberately, in one place.** Don't leave it to

whatever the installed SST happens to default to. The idiom is a single global `$transform(sst.aws.Function, (args) => { args.runtime ??= "nodejs24.x" })` in `run()` — `??=` is correct here (the transform runs before the component applies its own default, so it fills in only when the user didn't set one). Recent SST already defaults to a current Node runtime, so check the installed default first (Context7); the transform is then version-independence insurance so a future SST downgrade can't silently move your fleet. See `references/authoring.md`.

• **Never interpolate a Pulumi `Output<T>` into a plain JS template literal.**

Use `$interpolate` (or `pulumi.interpolate`). A bare top-level `` `${bucket.arn}/*` `` stringifies the `Output` to a `[Output<T>]` placeholder and produces a broken ARN that only fails at deploy time (it type-checks and `sst dev` runs fine). The fix is `$interpolate`​`` `${bucket.arn}/*` ``. This has caused prod deploy outages. See `references/authoring.md` § Outputs.

• **Migrating a resource between Pulumi *types* should default to two PRs** —

Pulumi creates-before-destroys, so for a uniqueness-constrained AWS name (bucket, IAM role, gateway) the old resource still owns it and the create fails with `ConflictException`. Two sequential deploys (teardown, then recreate) is the conservative default; `aliases:` / `pulumi import` / state surgery can bridge identity in some cases but only with a reviewed plan. See `references/deploy-and-troubleshoot.md` § Migrations.

• **Prefer typed `sst.aws.*` / `aws.*` resources over the

`aws.cloudcontrol.Resource` escape hatch.** CloudControl outputs are stringly-typed and `oneOf` fields don't patch