lerna

What is lerna?

Lerna is a tool that optimizes the workflow around managing multi-package repositories with git and npm. It allows you to manage your project's dependencies, versioning, and publishing in a more organized manner, especially when dealing with a monorepo containing multiple packages.

What are lerna's main functionalities?

Bootstrap

Installs all of the dependencies for each package, links any cross-dependencies, and ensures that each package can find and use the correct versions of each other.

lerna bootstrap

Publish

Helps with versioning of the changes and publishing packages that have been updated to npm. It can automatically determine version bumps based on conventional commits, create git tags, and push releases to the repository.

lerna publish

Run

Runs an npm script in each package that contains that script. The '--scope' flag can be used to run the script only in specified packages.

lerna run --scope my-package test

Exec

Executes an arbitrary command in each of your packages. In this example, it removes the 'node_modules' directory from each package.

lerna exec -- rm -rf ./node_modules

List

Lists all of the public packages in the current Lerna repo.

lerna list

Changed

Lists public packages that have changed since the last tagged release.

lerna changed

Diff

Shows the diff since the last release for a single package or all packages.

lerna diff

Import

Imports an external repository into the 'packages' folder of your Lerna monorepo, preserving the commit history.

lerna import <path-to-external-repository>

Other packages similar to lerna

nx

Nx is a suite of powerful, extensible dev tools that help you develop, test, build, and scale Angular and React applications with fully integrated support for monorepo management. It provides a more integrated experience for building applications compared to Lerna, which is more focused on package management.

README

Lerna is a fast modern build system for managing and publishing multiple JavaScript/TypeScript packages from the same repository.

Usage

Check out our docs site here.

Changelog

6.0.0 (2022-10-12)

Super fast, modern task-runner implementation for lerna run

As of version 6.0.0, Lerna will now delegate the implementation details of the lerna run command to the super fast, modern task-runner (powered by Nx) by default.

If for some reason you wish to opt in to the legacy task-runner implementation details (powered by p-map and p-queue), you can do so by setting "useNx": false in your lerna.json. (Please let us know via a Github issue if you feel the need to do that, however, as in general the new task-runner should just work how you expect it to as a lerna user).

Interactive configuration for lerna run caching and task pipelines via the new lerna add-caching command

When using the modern task-runner implementation described above, the way to get the most out of it is to tell it about the outputs of your various scripts, and also any relationships that exist between them (such as needing to run the build script before the test, for example).

Simply run lerna add-caching and follow the instructions in order to generate all the relevant configuration for your workspace.

You can learn more about the configuration it generates here: https://lerna.js.org/docs/concepts/task-pipeline-configuration

Automatic loading of .env files in lerna run with the new task-runner implementation

By default the modern task runner powered by Nx will automatically load .env files for you. You can set --load-env-files to false if you want to disable this behavior for any reason.

For more details about what .env files will be loaded by default please see: https://nx.dev/recipes/environment-variables/define-environment-variables

Obsolete options in lerna run with the new task-runner implementation

There are certain legacy options for lerna run which are no longer applicable to the modern task-runner. Please see full details about those flags, and the reason behind their obselence, here:

https://lerna.js.org/docs/lerna6-obsolete-options

New lerna repair command

When configuration changes over time as new versions of a tool are published it can be tricky to keep up with the changes and sometimes it's possible to miss out on optimizations as a result.

When you run the new command lerna repair, lerna will execute a series of code migrations/codemods which update your workspace to the latest and greatest best practices for workspace configuration.

The actual codemods which run will be added to over time, but for now one you might see run on your workspace is that it will remove any explicit "useNx": true references from lerna.json files, because that is no longer necessary and it's cleaner not to have it.

We are really excited about this feature and how we can use it to help users keep their workspaces up to date.