yarn import

Generates `yarn.lock` from an existing npm-installed `node_modules` folder.

yarn import

This command assists the migration of projects currently relying on npm-shrinkwrap.json, minimizing the differences between the lockfile and the existing dependency tree as best as it can.

Motivation

Many projects currently use npm shrinkwrap or check their node_modules into source control because they have fragile dependency trees. These projects can’t easily migrate to Yarn, because yarn install could produce a wildly different logical dependency tree. Not all trees can be represented by Yarn’s yarn.lock, and some valid trees will be automatically deduped upon install. These nuances and others present a significant barrier to manual migration.

yarn import aims to alleviate this challenge by generating a yarn.lock file using the versions found inside node_modules according to normal require.resolve() resolution rules. In cases where the Yarn resolution mechanism can’t satisfy the existing dependency tree identically, alerts will be made so that you may manually review the changes. The existing node_modules tree will be checked for validity beforehand, and the resultant lockfile should be yarn installable without any surprises (failed compatibility, unresolvable dependencies, auto-dedupes, etc.)

$ yarn import

yarn import vx.x.x
success Folder in sync.
warning Using version "2.2.4" of "lru-cache" instead of "2.7.3" for "ngstorage > grunt > minimatch"
warning Using version "2.0.6" of "readable-stream" instead of "2.2.9" for "ngstorage > karma > chokidar > readdirp"
[...]
success Saved lockfile.
✨  Done in 11.96s.