yarn (npm ecosystem)

Bomly uses this chain when it finds yarn evidence.

How yarn resolves

The default chain is lockfile-first: yarn-detector parses yarn.lock (classic v1 or Berry v2/v3/v4) and produces a full transitive graph. The native variant shells out to yarn list; Syft is the final fallback.

Network behavior

✅ The default yarn-detector is fully offline-safe. It reads yarn.lock and does not run any subprocess.

⚠️ yarn-native-detector runs yarn list. With a complete lockfile and an installed node_modules directory, yarn produces output from local state.

Prerequisites

• A committed yarn.lock. Both classic v1 (# yarn lockfile v1 header) and Berry v6+ are supported.
• No Node.js or Yarn installation is required to scan. Bomly parses the lockfile directly.
• For --install-first: yarn on PATH.

--install-first

yarn supports --install-first. When passed, Bomly runs yarn install before resolving the graph.

⚠️ --install-first downloads packages from the npm registry. Use it only when the lockfile is missing or stale.

bomly scan --install-first

Customizing the install command

Append flags to yarn install with repeatable --install-arg. Requires --detectors yarn-detector.

# Refuse to update the lockfile and skip optional deps
bomly scan --install-first --detectors yarn-detector \
  --install-arg --frozen-lockfile --install-arg --ignore-optional

Examples

Pin a transitive vulnerability

Use resolutions in package.json:

{
  "resolutions": {
    "**/lodash": "4.17.21"
  }
}

Re-lock: yarn install. Re-scan.

Berry workspaces

Bomly walks Berry workspaces and scans each as a subproject. Plug-and-Play (.pnp.cjs) projects are read through the lockfile, not the runtime resolver — graph fidelity matches the lockfile.

Reachability (experimental)

Experimental. Reachability is opt-in via --analyze. The feature is stable in shape but may evolve; ecosystem coverage is expanding.

For Yarn packages, the analyzer is jsreach at Tier-3 (package) — same caveats as npm. See REACHABILITY.md.

jsreach reads workspace arrays and Yarn-style workspaces.packages objects automatically, then follows imports between consumed sibling packages by package name.

Limitations

• Yarn Berry workspaces with injected: true dependencies are followed as regular edges.
• portal: and link: protocols point to local checkouts; their internal dependencies are read from the local package, not the registry.
• Subpath imports collapse to the package name for reachability.