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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/)

Recovering from a network error​

In the case that some packages were successfully published and others were not, lerna publish may have left the repository in an inconsistent state with some changed files. To recover from this, reset any extraneous local changes from the failed run to get back to a clean working tree. Then, retry the same lerna publish command. Lerna will attempt to publish all of the packages again, but will recognize those that have already been published and skip over them with a warning.

If you used the lerna publish command without positional arguments to select a new version for the packages, then you can run lerna publish from-git to retry publishing that same already-tagged version instead of having to bump the version again while retrying.

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

How does Lerna detect packages?​

By default, Lerna uses the workspaces property in package.json to search for packages. For details on this property, see the npm documentation or the Yarn documentation.

If you are using pnpm, you might have set npmClient to pnpm in lerna.json. In this case, Lerna will use the packages property in pnpm-workspace.yaml to search for packages. For details on this property, see the pnpm documentation.

If you are using an older version of Lerna or have explicitly opted out of using workspaces, then Lerna will use the packages property in lerna.json to search for packages.