midgard-yarn-strict

midgard-yarn-strict is a stopgap package manager for handling large scale monorepos. The goal is to ultimately use npm so we can lean on the npm team to deliver a first class support for our package manager. Until all the blockers of using npm are resolved, midgard-yarn-strict is this solution.

midgard-yarn-strict is a fork of midgard-yarn, which is itself a fork of yarn v1.

Improvements over yarn

• [reliability] retry on more errors.
• [performance] detect abnormally long requests and when detected create racing requests.
• [performance] use workers to copy files from cache to node_modules.
• [performance] optimize cycle-detection algorithm from o(n2) to o(n.log(n)).
• [feature] add support for --frozen-lockfile in monorepos.
• [bug fix] yarn would not properly remove scoped package from node_modules after uninstalling this dependency.
• [performance and reliability] optimize creation of bin scripts for large repos.

Improvements over midgard-yarn

• midgard-yarn-strict implementes the isolated-mode npm's RFC. This brings the following benefits:
  • scoped install: unrelated workspaces will not impact your installation time.
  • performance: isolated-mode allows for a maximal de-duplication of dependencies, which leads to lower installation time.
  • incremental installation: the performance of the installation depends only on packages that have never been installed before. This means that switching back and forth between two branches is very fast.

Usage

Install

Instead of yarn install, run

$ npx midgard-yarn-strict

The installation flags supported by yarn are not supported by the CLI but some are still supported via the yarn config file.

Optionally a scope can be given:

$ `npx midgard-yarn-strict "build-tools-*"` 

This will install the dependencies of the local packages matching the glob provided.

By default, midgard-yarn-strict does incremental installs by storing a .hash in each node_modules directory.

If you want to run without leveraging incremental, you can run with the --skip-cache flag, or alternatively, you can simply rm -rf path/to/packages/*/node_modules/.hash.

Upgrade or add a dependency

Manual edits to the package.json files is the only current supported way to manage dependencies, no CLI tool is available yet.

yarn link

Not supported yet.

yarn run

The yarn-run command is not affected by midgard-yarn-strict, so you can still run yarn test for example.

Configuration

midgard-yarn-strict allows you to declare dependencies on behalf of external packages, this is useful when external packages forgot to declare all their dependencies.

In the example below, webpack with a version matching "^4.0.0" will be installed as if it had declared a dependency on webpack-cli.

Using package.json

{
  // rest of package.json
  "extraDependencies": {
    "webpack": {
      "^4.0.0": {
        "dependencies": {
          "webpack-cli": "^4.0.0"
        }
      }
    }
  }
}

Using extraDependencies.json

{
  "webpack": {
    "^4.0.0": {
      "dependencies": {
        "webpack-cli": "^4.0.0"
      }
    }
  }
}

Prior art

This package manager is built on the learnings brought by npm, yarn and pnpm.