Skip to main content

Frequently asked questions

This document is a work in progress.

How do I add a package to my Lerna repository?​

For any packages that you add to your Lerna repository, instead of running npm install you should run lerna bootstrap. This will take into account the existing projects in the packages folder as well as external dependencies.

New packages​

Create a directory for your package in the packages folder, and run npm init as normal to create the package.json for your new package.

Existing packages​

You can use lerna import <package> to transfer an existing package into your Lerna repository; this command will preserve the commit history.

lerna import <package> takes a local path rather than a URL. In this case you will need to have the repo you wish to link to on your file system.

How do I retry publishing if publish fails?​

Sometimes, lerna publish does not work. Your network may have had a hiccup, you may have not been logged on to npm, etc.

If the lerna.json has not yet been updated, simply try lerna publish again.

If it has been updated, you can force re-publish. lerna publish --force-publish $(ls packages/)

The bootstrap process is really slow, what can I do?​

Projects having many packages inside them could take a very long time to bootstrap.

You can significantly reduce the time spent in lerna bootstrap if you turn on hoisting, see the hoisting docs for more information.

In combination with that you may increase the bootstrap performance even more by using yarn as an npm client instead of npm.

Root package.json​

The root package.json, at the very least, is how you install lerna locally during a CI build. You should also put your testing, linting and similar tasks there to run them from root as running them separately from each package is slower. The root can also hold all the "hoisted" packages, which speeds up bootstrapping when using the --hoist flag.

CI setup​

As mentioned above root package.json is responsible for installing lerna locally. You need to automate bootstrap though. This can be achieved by putting it as npm script to use it during CI phases.

Example root package.json:

{
  "name": "my-monorepo",
  "private": true,
  "devDependencies": {
    "eslint": "^3.19.0",
    "jest": "^20.0.4",
    "lerna": "^2.0.0"
  },
  "scripts": {
    "bootstrap": "lerna bootstrap --hoist",
    "pretest": "eslint packages",
    "test": "jest"
  }
}

Example CircleCI's configuration file (circle.yml):

dependencies:
  post:
    - npm run bootstrap