@skedulo/mex-fn-build

Bundler CLI for Skedulo MEX shared connected functions. A shared-function project depends on this as its single build devDependency and runs it via yarn bundle (which is just mex-fn-build). The same CLI runs locally and in the cloud builder, so a local bundle matches the cloud bundle exactly.

Commands

mex-fn-build (default, bundle)

Run from a shared-function project root, in strict order:

1. Bundle src/index.backend.ts → dist/index.backend.js with esbuild.
2. Load the sharedFunctionFactory export from the freshly-built bundle.
3. Read libVersion from the project's installed @skedulo/mex-service-libs.
4. Derive feature descriptors via the project's describeSharedResources. Offline the resource thunk throws (no tenant token), so it falls back to an empty resource list + the real changeSets; the cloud builder re-derives and overwrites features.resources.
5. Write dist/info.json = { libVersion, features }.

mex-fn-build serve [--port N]

Boots a local Koa dev server over the function's routes so a developer can exercise handlers before deploying. It rebuilds a non-minified dev bundle (dist/index.backend.dev.js, so the shipped dist/index.backend.js stays untouched), then wraps the bundle's handler dispatcher in Koa. Routes: POST /resource_fetch, /resource_descriptor, /changeset, /changeset_after.

Auth is per request via Authorization: Bearer <jwt> + Sked-Api-Server: <baseUrl> headers; for convenience these are injected from SKED_API_TOKEN / SKED_BASE_URL when a request omits them. Port defaults to 3000 (--port or PORT). koa / koa-bodyparser resolve from the project's SDK — no dependency is added.

Why it resolves the SDK from the project

The CLI declares no dependency on @skedulo/mex-service-libs. It resolves the SDK — both the libVersion and the derivation helpers — from the consuming project's node_modules (require.resolve(id, { paths: [projectRoot] })), the same discipline the cloud builder uses. If the CLI carried its own SDK copy, libVersion would reflect the CLI's pin instead of the version the function was authored against, silently mis-selecting the fetch/save invocation contract.

Usage

In a shared-function project:

// package.json
{
  "scripts": {
    "bundle": "mex-fn-build",
    "start": "mex-fn-build serve"
  },
  "devDependencies": { "@skedulo/mex-fn-build": "^0.0.1" }
}

yarn bundle          # -> dist/index.backend.js + dist/info.json
yarn start           # local dev server on :3000 (SKED_BASE_URL / SKED_API_TOKEN)

Local development of this package

Uses an isolated npm toolchain (independent of the repo's root Yarn project):

cd tools/mex-fn-build
npm install
npm run build        # tsc -> dist/cli.js