Presets & Units

Straight Jacket uses a composable unit system instead of monolithic Dockerfiles.

Concepts

A unit is a reusable component — a set of packages, Dockerfile snippets, PATH entries, and build args.

A preset is a named composition of units.

┌─────────────────────────────────────────────────┐
│  Preset: full-stack                             │
│  ┌───────────┐ ┌──────┐ ┌─────┐ ┌───────────┐   │
│  │ dev-utils │ │ node │ │ bun │ │ github-cli│   │
│  └───────────┘ └──────┘ └─────┘ └───────────┘   │
└─────────────────────────────────────────────────┘

Straight Jacket generates a multi-stage Dockerfile from the preset's units, builds it once, and content-hash tags the image. Repos sharing the same preset share the same image — no redundant builds.

Built-in Presets

Preset	Units	Use Case
full-stack	dev-utils, node, bun, github-cli, doc-utils	Web apps, JS/TS projects
full-stack-playwright	full-stack + playwright	E2E testing, browser automation
rust-wasm	dev-utils, node, rust, wasm, github-cli	WebAssembly development
il2cpp-re	dev-utils, node, github-cli, java, dotnet, rust, ghidra, jadx, il2cpp-tools	Reverse engineering

Built-in Units

Unit	What It Provides
dev-utils	git, build-essential, zsh, ripgrep, jq, fd, bat, tree, and 30+ essential dev tools
node	Node.js (configurable version, default: 24)
bun	Bun JavaScript runtime
rust	Rust via rustup (configurable version)
wasm	Binaryen, wasmtime, wasm-tools
github-cli	GitHub CLI (gh)
doc-utils	pandoc, PDF tools, OCR, document processing
playwright	Playwright + Chromium for browser automation
java	OpenJDK 21
dotnet	.NET SDK 8.0 + ILSpy CLI
ghidra	Ghidra reverse engineering framework (multi-stage build)
jadx	Dex-to-Java decompiler
il2cpp-tools	IL2CPP/Unity reverse engineering toolkit

Custom Presets

Create your own presets to define exactly the environment you need.

Per-Repo Preset

mkdir -p .sj/presets/my-preset

// .sj/presets/my-preset/preset.json
{
  "name": "my-preset",
  "units": [
    { "name": "dev-utils" },
    { "name": "node", "args": { "version": "20" } },
    { "name": "rust", "args": { "version": "nightly" } }
  ]
}

User-Level Preset

mkdir -p ~/.config/sj/presets/my-preset
# Same preset.json format

Resolution Order

Presets resolve in priority order:

1. Per-repo — .sj/presets/<name>/preset.json
2. User — ~/.config/sj/presets/<name>/preset.json
3. Built-in — embedded in the sj binary

Custom Units

Create custom units with their own packages and Dockerfile snippets:

mkdir -p ~/.config/sj/units/my-tools

A unit consists of:

• unit.json — manifest declaring packages, build args, PATH entries, and dependencies
• post-install.Dockerfile (optional) — injected after system deps are installed
• build.Dockerfile (optional) — standalone build stage for multi-stage builds
• post-agent-install.Dockerfile (optional) — injected after agent binaries are installed

See the built-in units in default-units/ for examples.

Units resolve with the same priority order as presets: per-repo > user > built-in.