@typeofweb/ignore-monorepo-buildstep

A package that adds monorepo support for Vercel's "Ignore build-step" setting. Small, fast, with 0 external dependencies.

The problem

By default, when working in a monorepo, each push triggers Vercel to rebuild all the projects even when changes were introduced only to some of them. It takes time and blocks the build pipeline for your team. Thanks to @typeofweb/ignore-monorepo-buildstep, this is no longer a problem – Vercel becomes smarter and only rebuilds what needs building!

@typeofweb/ignore-monorepo-buildstep helps you save time and money.

Example setup

Repo structure

Assume we're using pnpm workspaces and we have the following monorepo structure:

.
├── apps
│   ├── a
│   └── b
└── packages
    ├── common
    └── depA

Apps a and b both depend on the common package. Moreover, app a depends on depA package.

Vercel config

Add the following command to the "Ignore Build Step" section in your Vercel project settings:

npx @typeofweb/ignore-monorepo-buildstep

By default, ignore-monorepo-buildstep will compare HEAD^ and HEAD. You can override this and use an env variable exposed by Vercel:

npx @typeofweb/ignore-monorepo-buildstep $VERCEL_GIT_PREVIOUS_SHA

Result

When any changes are introduced to packages/common, both apps a and b will be built:

However, when packages/depA is modified, only apps/a is built while apps/b is skipped:

Moreover, deployment statuses are reported as successful even when builds are skipped:

How does it work?

@typeofweb/ignore-monorepo-buildstep analyses the structure of the monorepo. It reads pnpm-workspace.yaml and package.json of every package, and creates a tree of dependencies inside the monorepo.

Then, it proceeds to check whether the given package or any of its dependencies were modified since the last commit with the use of git diff "HEAD^" "HEAD" --quiet.

Currently, only pnpm workspaces are supported but more is on the roadmap.