Using Shared Packages in Firebase Monorepos

In a recent project I needed to share TypeScript types and utilities between my React frontend (Firebase Hosting) and Express backend (Firebase Cloud Functions).

file:../shared breaks Firebase deployment

I started with the obvious approach - referencing the shared package locally:

{
  "dependencies": {
    "@company/shared": "file:../shared"
  }
}

This works perfectly in development, but Firebase Functions deployment fails. The cloud build environment can't resolve the relative path ../shared since it only uploads your functions directory.

Use npm tarballs instead of relative paths

Use npm's tarball approach instead. In your functions package.json:

{
  "scripts": {
    "preinstall": "if [ -d ../shared ]; then npm pack ../shared; fi"
  },
  "dependencies": {
    "@company/shared": "file:./company-shared-1.0.0.tgz"
  }
}

The preinstall script creates a tarball locally (but skips in cloud via the if check). The tarball gets included in Firebase's deployment package.

Automate pack/deploy/unpack workflow

In your API package.json:

{
  "scripts": {
    "shared:pack": "npm pack ../shared && npm i $(ls -t ./company-shared-*.tgz | head -n1) --save",
    "shared:unpack": "npm i ../shared --save"
  }
}

In your root package.json for coordinated deployment:

{
  "scripts": {
    "api-shared-pack": "npm run shared:pack --prefix api",
    "api-shared-unpack": "npm run shared:unpack --prefix api",
    "api-deploy": "npm run api-shared-pack && firebase deploy --only functions && npm run api-shared-unpack"
  }
}

This automatically switches to tarball mode, deploys functions, then reverts to local development mode.