@typeofweb/ignore-monorepo-buildstep
A package that adds monorepo support for Vercel's "Ignore build-step" setting. Small, fast, with 0 external dependencies.
Why?
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!
In a real-life project such as saleor/react-storefront, we've saved up to 85% on Vercel build times – 6.6x speedup! @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 and yarn workspaces are supported but more is on the roadmap.
