A tool for managing JavaScript projects with multiple packages.
Splitting up large codebases into separate independently versioned packages is extremely useful for code sharing. However, making changes across many repositories is messy and difficult to track, and testing across repositories gets complicated really fast.
To solve these (and many other) problems, some projects will organize their codebases into multi-package repositories (sometimes called monorepos). Projects like Babel, React, Angular, Ember, Meteor, Jest, and many others develop all of their packages within a single repository.
Lerna is a tool that optimizes the workflow around managing multi-package repositories with git and npm.
Lerna can also reduce the time and space requirements for numerous copies of packages in development and build environments - normally a downside of dividing a project into many separate NPM package. See the hoist documentation for details.
There's actually very little to it. You have a file system that looks like this:
my-lerna-repo/
package.json
packages/
package-1/
package.json
package-2/
package.json
The two primary commands in Lerna are lerna bootstrap and lerna publish.
bootstrap will link dependencies in the repo together.
publish will help publish any updated packages.
The instructions below are for Lerna 2.x. We recommend using it instead of 1.x for a new Lerna project. Check the wiki if you need to see the 1.x README.
Let's start by installing Lerna globally with npm.
$ npm install --global lernaNext we'll create a new folder:
$ mkdir lerna-repo $ cd lerna-repoAnd now let's turn it into a Lerna repo:
$ lerna initThis will create a
lerna.jsonconfiguration file as well as apackagesfolder, so your folder should now look like this:lerna-repo/ packages/ package.json lerna.jsonLerna allows you to manage your project using one of two modes: Fixed or Independent.
Fixed mode Lerna projects operate on a single version line. The version is kept in the
lerna.jsonfile at the root of your project under theversionkey. When you runlerna publish, if a module has been updated since the last time a release was made, it will be updated to the new version you're releasing. This means that you only publish a new version of a package when you need to.This is the mode that Babel is currently using. Use this if you want to automatically tie all package versions together. One issue with this approach is that a major change in any package will result in all packages having a new major version.
Independent mode Lerna projects allows maintainers to increment package versions independently of each other. Each time you publish, you will get a prompt for each package that has changed to specify if it's a patch, minor, major or custom change.
Independent mode allows you to more specifically update versions for each package and makes sense for a group of components. Combining this mode with something like semantic-release would make it less painful. (There is work on this already at atlassian/lerna-semantic-release).
The
versionkey inlerna.jsonis ignored in independent mode.If you encounter any issues while using Lerna please check out our Troubleshooting document where you might find the answer to your problem.
See FAQ.md.
$ lerna initCreate a new Lerna repo or upgrade an existing repo to the current version of Lerna.
Lerna assumes the repo has already been initialized with
git init.When run, this command will:
- Add
lernaas adevDependencyinpackage.jsonif it doesn't already exist.- Create a
lerna.jsonconfig file to store theversionnumber.Example output on a new git repo:
$ lerna init lerna info version v2.0.0 lerna info Updating package.json lerna info Creating lerna.json lerna success Initialized Lerna files$ lerna init --independentThis flag tells Lerna to use independent versioning mode.
$ lerna init --exactBy default,
lerna initwill use a caret range when adding or updating the local version oflerna, just likenpm install --save-dev lerna.To retain the
lerna1.x behavior of "exact" comparison, pass this flag. It will configurelerna.jsonto enforce exact match for all subsequent executions.{ "command": { "init": { "exact": true } }, "version": "0.0.0" }$ lerna bootstrapBootstrap the packages in the current Lerna repo. Installs all of their dependencies and links any cross-dependencies.
When run, this command will:
npm installall external dependencies of each package.- Symlink together all Lerna
packagesthat are dependencies of each other.npm run prepublishin all bootstrapped packages.npm run preparein all bootstrapped packages.
lerna bootstraprespects the--ignore,--ignore-scripts,--scopeand--include-filtered-dependenciesflags (see Flags).Pass extra arguments to npm client by placing them after
--:$ lerna bootstrap -- --production --no-optionalMay also be configured in
lerna.json:{ ... "npmClient": "yarn", "npmClientArgs": ["--production", "--no-optional"] }Let's use
babelas an example.
babel-generatorandsource-map(among others) are dependencies ofbabel-core.babel-core'spackage.jsonlists both these packages as keys independencies, as shown below.$ lerna add <package>[@version] [--dev]Add local or remote
packageas dependency to packages in the current Lerna repo.When run, this command will:
- Add
packageto each applicable package. Applicable are packages that are notpackageand are in scope- Bootstrap packages with changes to their manifest file (
package.json)
lerna addrespects the--ignore,--scopeand--include-filtered-dependenciesflags (see Flags).lerna add module-1 --scope=module-2 # Install module-1 to module-2 lerna add module-1 --scope=module-2 --dev # Install module-1 to module-2 in devDependencies lerna add module-1 # Install module-1 in all modules except module-1 lerna add babel-core # Install babel-core in all modules// babel-core package.json { "name": "babel-core", ... "dependencies": { ... "babel-generator": "^6.9.0", ... "source-map": "^0.5.0" } }
- Lerna checks if each dependency is also part of the Lerna repo.
- In this example,
babel-generatorcan be an internal dependency, whilesource-mapis always an external dependency.- The version of
babel-generatorin thepackage.jsonofbabel-coreis satisfied bypackages/babel-generator, passing for an internal dependency.source-mapisnpm installed (oryarned) like normal.packages/babel-core/node_modules/babel-generatorsymlinks topackages/babel-generator- This allows nested directory imports
Notes:
- When a dependency version in a package is not satisfied by a package of the same name in the repo, it will be
npm installed (oryarned) like normal.- Dist-tags, like
latest, do not satisfy semver ranges.- Circular dependencies result in circular symlinks which may impact your editor/IDE.
Webstorm locks up when circular symlinks are present. To prevent this, add
node_modulesto the list of ignored files and folders inPreferences | Editor | File Types | Ignored files and folders.$ lerna publishPublish packages in the current Lerna project. When run, this command does the following:
Creates a new release of the packages that have been updated. Prompts for a new version. Creates a new git commit/tag in the process of publishing to npm.
More specifically, this command will:
- Run the equivalent of
lerna updatedto determine which packages need to be published.- If necessary, increment the
versionkey inlerna.json.- Update the
package.jsonof all updated packages to their new versions.- Update all dependencies of the updated packages with the new versions, specified with a caret (^).
- Create a new git commit and tag for the new version.
- Publish updated packages to npm.
Lerna won't publish packages which are marked as private (
"private": truein thepackage.json).Note: to publish scoped packages, you need to add the following to each
package.json:"publishConfig": { "access": "public" }$ lerna publish --exactWhen run with this flag,
publishwill specify updated dependencies in updated packages exactly (with no punctuation), instead of as semver compatible (with a^).For more information, see the package.json dependencies documentation.
$ lerna publish --npm-tag=nextWhen run with this flag,
publishwill publish to npm with the given npm dist-tag (defaults tolatest).This option can be used to publish a
prereleaseorbetaversion.Note: the
latesttag is the one that is used when a user runsnpm install my-package. To install a different tag, a user can runnpm install my-package@prerelease.$ lerna publish --canary $ lerna publish --canary=betaWhen run with this flag,
publishpublishes packages in a more granular way (per commit). Before publishing to npm, it creates the newversiontag by taking the currentversion, bumping it to the next minor version, adding the provided meta suffix (defaults toalpha) and appending the current git sha (ex:1.0.0becomes1.1.0-alpha.81e3b443).The intended use case for this flag is a per commit level release or nightly release.
$ lerna publish --conventional-commitsWhen run with this flag,
publishwill use the Conventional Commits Specification to determine the version bump and generate CHANGELOG$ lerna publish --conventional-commits --changelog-preset angular-bitbucketBy default, the changelog preset is set to
angular. In some cases you might want to change either use a another preset or a custom one.Presets are names of built-in or installable configuration for conventional changelog. Presets may be passed as the full name of the package, or the auto-expanded suffix (e.g.,
angularis expanded toconventional-changelog-angular).$ lerna publish --git-remote upstreamWhen run with this flag,
publishwill push the git changes to the specified remote instead oforigin.$ lerna publish --skip-gitWhen run with this flag,
publishwill publish to npm without running any of the git commands.Only publish to npm; skip committing, tagging, and pushing git changes (this only affects publish).
$ lerna publish --skip-npmWhen run with this flag,
publishwill update allpackage.jsonpackage versions and dependency versions, but it will not actually publish the packages to npm.This flag can be combined with
--skip-gitto just update versions and dependencies, without committing, tagging, pushing or publishing.Only update versions and dependencies; don't actually publish (this only affects publish).
$ lerna publish --force-publish=package-2,package-4 # force publish all packages $ lerna publish --force-publish=*When run with this flag,
publishwill force publish the specified packages (comma-separated) or all packages using*.This will skip the
lerna updatedcheck for changed packages and forces a package that didn't have agit diffchange to be updated.$ lerna publish --canary --yes # skips `Are you sure you want to publish the above changes?`When run with this flag,
publishwill skip all confirmation prompts. Useful in Continuous integration (CI) to automatically answer the publish confirmation prompt.$ lerna publish --cd-version (major | minor | patch | premajor | preminor | prepatch | prerelease) # uses the next semantic version(s) value and this skips `Select a new version for...` promptWhen run with this flag,
publishwill skip the version selection prompt (in independent mode) and use the next specified semantic version. You must still use the--yesflag to avoid all prompts. This is useful when build systems need to publish without command prompts. Works in both normal and independent modes.If you have any packages with a prerelease version number (e.g.
2.0.0-beta.3) and you runlerna publishwith--cd-versionand a non-prerelease version increment (major / minor / patch), it will publish those packages in addition to the packages that have changed since the last release.$ lerna publish --cd-version=prerelease # uses the next semantic prerelease version, e.g. # 1.0.0 => 1.0.0-0 $ lerna publish --cd-version=prepatch --preid=next # uses the next semantic prerelease version with a specific prerelease identifier, e.g. # 1.0.0 => 1.0.1-next.0When run with this flag,
lerna publish --cd-versionwill incrementpremajor,preminor,prepatch, orprereleaseversions using the specified prerelease identifier.$ lerna publish --repo-version 1.0.1 # applies version and skips `Select a new version for...` promptWhen run with this flag,
publishwill skip the version selection prompt and use the specified version. Useful for bypassing the user input prompt if you already know which version to publish.$ lerna publish -m "chore(release): publish %s" # commit message = "chore(release): publish v1.0.0" $ lerna publish -m "chore(release): publish %v" # commit message = "chore(release): publish 1.0.0" $ lerna publish -m "chore(release): publish" --independent # commit message = "chore(release): publish # # - package-1@3.0.1 # - package-2@1.5.4"When run with this flag,
publishwill use the provided message when committing the version updates for publication. Useful for integrating lerna into projects that expect commit messages to adhere to certain guidelines, such as projects which use commitizen and/or semantic-release.If the message contains
%s, it will be replaced with the new global version version number prefixed with a "v". If the message contains%v, it will be replaced with the new global version version number without the leading "v". Note that this only applies when using the default "fixed" versioning mode, as there is no "global" version when using--independent.This can be configured in lerna.json, as well:
{ "command": { "publish": { "message": "chore(release): publish %s" } } }Lerna allows you to specify a glob or an array of globs in your
lerna.jsonthat your current branch needs to match to be publishable. You can use this flag to override this setting. If yourlerna.jsoncontains something like this:{ "command": { "publish": { "allowBranch": "master" } } }{ "command": { "publish": { "allowBranch": ["master", "feature/*"] } } }and you are not on the branch
masterlerna will prevent you from publishing. To force a publish despite this config, pass the--allow-branchflag:$ lerna publish --allow-branch my-new-feature$ lerna updatedCheck which
packageshave changed since the last release (the last git tag).Lerna determines the last git tag created and runs
git diff --name-only v6.8.1to get all files changed since that tag. It then returns an array of packages that have an updated file.Note that configuration for the
publishcommand also affects theupdatedcommand. For examplecommand.publish.ignoreChanges$ lerna updated --jsonWhen run with this flag,
updatedwill return an array of objects in the following format:[ { "name": "package", "version": "1.0.0", "private": false } ]$ lerna cleanRemove the
node_modulesdirectory from all packages.
lerna cleanrespects the--ignore,--scope, and--yesflags (see Flags).$ lerna diff [package?] $ lerna diff # diff a specific package $ lerna diff package-nameDiff all packages or a single package since the last release.
Similar to
lerna updated. This command runsgit diff.$ lerna lsList all of the public packages in the current Lerna repo.
lerna lsrespects the--ignoreand--scopeflags (see Flags).$ lerna ls --jsonWhen run with this flag,
lswill return an array of objects in the following format:[ { "name": "package", "version": "1.0.0", "private": false } ]$ lerna run <script> -- [..args] # runs npm run my-script in all packages that have it $ lerna run test $ lerna run build # watch all packages and transpile on change, streaming prefixed output $ lerna run --parallel watchRun an npm script in each package that contains that script. A double-dash (
--) is necessary to pass dashed arguments to the script execution.
lerna runrespects the--concurrency,--scope,--ignore,--stream, and--parallelflags (see Flags).$ lerna run --scope my-component testNote: It is advised to constrain the scope of this command (and
lerna exec, below) when using the--parallelflag, as spawning dozens of subprocesses may be harmful to your shell's equanimity (or maximum file descriptor limit, for example). YMMV$ 6052 lerna exec -- <command> [..args] # runs the command in all packages $ lerna exec -- rm -rf ./node_modules $ lerna exec -- protractor conf.jsRun an arbitrary command in each package. A double-dash (
--) is necessary to pass dashed flags to the spawned command, but is not necessary when all the arguments are positional.
lerna execrespects the--concurrency,--scope,--ignore,--streamand--parallelflags (see Flags).$ lerna exec --scope my-component -- ls -laTo spawn long-running processes, pass the
--parallelflag:# transpile all modules as they change in every package $ lerna exec --parallel -- babel src -d lib -wYou may also get the name of the current package through the environment variable
LERNA_PACKAGE_NAME:$ lerna exec -- npm view \$LERNA_PACKAGE_NAMEYou may also run a script located in the root dir, in a complicated dir structure through the environment variable
LERNA_ROOT_PATH:$ lerna exec -- node \$LERNA_ROOT_PATH/scripts/some-script.jsHint: The commands are spawned in parallel, using the concurrency given (except with
--parallel). The output is piped through, so not deterministic. If you want to run the command in one package after another, use it like this:$ lerna exec --concurrency 1 -- ls -la$ lerna exec --bail=<boolean> <command>This flag signifies whether or not the
execcommand should halt execution upon encountering an error thrown by one of the spawned subprocesses. Its default value istrue.$ lerna import <path-to-external-repository>Import the package at
<path-to-external-repository>, with commit history, intopackages/<directory-name>. Original commit authors, dates and messages are preserved. Commits are applied to the current branch.This is useful for gathering pre-existing standalone packages into a Lerna repo. Each commit is modified to make changes relative to the package directory. So, for example, the commit that added
package.jsonwill instead addpackages/<directory-name>/package.json.$ lerna linkSymlink together all Lerna
packagesthat are dependencies of each other in the current Lerna repo.$ lerna link --force-localWhen passed, this flag causes the
linkcommand to always symlink local dependencies regardless of matching version range.Lerna will log to a
lerna-debug.logfile (same asnpm-debug.log) when it encounters an error running a command.Lerna also has support for scoped packages.
Running
lernawithout arguments will show all commands/options.{ "version": "1.1.3", "command": { "publish": { "ignoreChanges": [ "ignored-file", "*.md" ] }, "bootstrap": { "ignore": "component-*" } }, "packages": ["packages/*"] }
version: the current version of the repository.command.publish.ignoreChanges: an array of globs that won't be included inlerna changed/publish. Use this to prevent publishing a new version unnecessarily for changes, such as fixing aREADME.mdtypo.command.bootstrap.ignore: an array of globs that won't be bootstrapped when running thelerna bootstrapcommand.command.bootstrap.scope: an array of globs that restricts which packages will be bootstrapped when running thelerna bootstrapcommand.packages: Array of globs to use as package locations.Most
devDependenciescan be pulled up to the root of a Lerna repo.This has a few benefits:
- All packages use the same version of a given dependency
- Can keep dependencies at the root up-to-date with an automated tool such as GreenKeeper
- Dependency installation time is reduced
- Less storage is needed
Note that
devDependenciesproviding "binary" executables that are used by npm scripts still need to be installed directly in each package where they're used.For example the
nspdependency is necessary in this case forlerna run nsp(andnpm run nspwithin the package's directory) to work correctly:{ "scripts": { "nsp": "nsp" }, "devDependencies": { "nsp": "^2.3.3" } }Lerna allows target versions of local dependent packages to be written as a git remote url with a
committish(e.g.,#v1.0.0or#semver:^1.0.0) instead of the normal numeric version range. This allows packages to be distributed via git repositories when packages must be private and a private npm registry is not desired.Please note that lerna does not perform the actual splitting of git history into the separate read-only repositories. This is the responsibility of the user. (See this comment for implementation details)
// packages/pkg-1/package.json { name: "pkg-1", version: "1.0.0", dependencies: { "pkg-2": "github:example-user/pkg-2#v1.0.0" } } // packages/pkg-2/package.json { name: "pkg-2", version: "1.0.0" }In the example above,
lerna bootstrapwill properly symlinkpkg-2intopkg-1.lerna publishwill update the committish (#v1.0.0) inpkg-1whenpkg-2changes.Options to Lerna can come from configuration (
lerna.json) or on the command line. Additionally options in config can live at the top level or may be applied to specific commands.Example:
{ "version": "1.2.0", "exampleOption": "foo", "command": { "init": { "exampleOption": "bar" } } }In this case
exampleOptionwill be "foo" for all commands exceptinit, where it will be "bar". In all cases it may be overridden to "baz" on the command-line with--example-option=baz.How many threads to use when Lerna parallelizes the tasks (defaults to
4)$ lerna publish --concurrency 1Scopes a command to a subset of packages.
$ lerna exec --scope my-component -- ls -la$ lerna run --scope toolbar-* testWhen executing a script or command, scope the operation to packages that have been updated since the specified
ref. Ifrefis not specified, it defaults to the latest tag.List the contents of packages that have changed since the latest tag:
$ lerna exec --since -- ls -laRun the tests for all packages that have changed since
master:$ lerna run test --since masterList all packages that have changed since
some-branch:$ lerna ls --since some-branchThis can be particularly useful when used in CI, if you can obtain the target branch a PR will be going into, because you can use that as the
refto the--sinceoption. This works well for PRs going into master as well as feature branches.When importing repositories with merge commits with conflicts, the import command will fail trying to apply all commits. The user can use this flag to ask for import of "flat" history, i.e. with each merge commit as a single change the merge introduced.
$ lerna import ~/Product --flattenExcludes a subset of packages when running a command.
$ lerna bootstrap --ignore component-*The
ignoreflag, when used with thebootstrapcommand, can also be set inlerna.jsonunder thecommand.bootstrapkey. The command-line flag will take precedence over this option.Example
{ "version": "0.0.0", "command": { "bootstrap": { "ignore": "component-*" } } }Hint: The glob is matched against the package name defined in
package.json, not the directory name the package lives in.When used with the
bootstrapcommand it won't run any lifecycle scripts in bootstrapped packages.$ lerna bootstrap --ignore-scriptsUsed in combination with any command that accepts
--scope(bootstrap,clean,ls,run,exec). Ensures that all dependencies (and dev dependencies) of any scoped packages (either through--scopeor--ignore) are operated on as well.Note: This will override the
--scopeand--ignoreflags.i.e. A package matched by the
--ignoreflag will still be bootstrapped if it is depended on by another package that is being bootstrapped.This is useful for situations where you want to "set up" a single package that relies on other packages being set up.
$ lerna bootstrap --scope my-component --include-filtered-dependencies # my-component and all of its dependencies will be bootstrapped$ lerna bootstrap --scope "package-*" --ignore "package-util-*" --include-filtered-dependencies # all package-util's will be ignored unless they are depended upon by a # package matched by "package-*"What level of logs to report. On failure, all logs are written to lerna-debug.log in the current working directory.
Any logs of a higher level than the setting are shown. The default is "info".
Set a max buffer length for each underlying process call. Useful for example when someone wants to import a repo with a larger amount of commits while running
lerna import. In that case the built-in buffer length might not be sufficient.By default, all tasks execute on packages in topologically sorted order as to respect the dependency relationships of the packages in question. Cycles are broken on a best-effort basis in a way not guaranteed to be consistent across Lerna invocations.
Topological sorting can cause concurrency bottlenecks if there are a small number of packages with many dependents or if some packages take a disproportionately long time to execute. The
--no-sortoption disables sorting, instead executing tasks in an arbitrary order with maximum concurrency.This option can also help if you run multiple "watch" commands. Since
lerna runwill execute commands in topologically sorted order, it can end up waiting for a command before moving on. This will block execution when you run "watch" commands, since they typically never end. An example of a "watch" command is runningbabelwith the--watchCLI flag.Install external dependencies matching
globat the repo root so they're available to all packages. Any binaries from these dependencies will be linked into dependent packagenode_modules/.bin/directories so they're available for npm scripts. If the option is present but noglobis given the default is**(hoist everything). This option only affects thebootstrapcommand.$ lerna bootstrap --hoistFor background on
--hoist, see the hoist documentation.Note: If packages depend on different versions of an external dependency, the most commonly used version will be hoisted, and a warning will be emitted.
Do not install external dependencies matching
globat the repo root. This can be used to opt out of hoisting for certain dependencies.$ lerna bootstrap --hoist --nohoist=babel-*Install external dependencies using
[client] install. Must be an executable that knows how to install npm dependencies.$ lerna bootstrap --npm-client=yarnMay also be configured in
lerna.json:{ ... "npmClient": "yarn" }Fail immediately if a cycle is found (in
bootstrap,exec,publishorrun).$ lerna bootstrap --reject-cyclesEnables integration with Yarn Workspaces (available since yarn@0.27+). The values in the array are the commands in which Lerna will delegate operation to Yarn (currently only bootstrapping). If
--use-workspacesis true thenpackageswill be overridden by the value frompackage.json/workspaces.May also be configured inlerna.json:{ ... "npmClient": "yarn", "useWorkspaces": true }The root-level package.json must also include a
workspacesarray:{ "private": true, "devDependencies": { "lerna": "^2.2.0" }, "workspaces": ["packages/*"] }This list is broadly similar to lerna's
packagesconfig (a list of globs matching directories with a package.json), except it does not support recursive globs ("**", a.k.a. "globstars").Stream output from child processes immediately, prefixed with the originating package name. This allows output from different packages to be interleaved.
$ lerna run watch --streamSimilar to
--stream, but completely disregards concurrency and topological sorting, running a given command or script immediately in all matching packages with prefixed streaming output. This is the preferred flag for long-running processes such asbabel src -d lib -wrun over many packages.$ lerna exec --parallel -- babel src -d lib -wWhen run with this flag, forwarded npm commands will use the specified registry for your package(s).
This is useful if you do not want to explicitly set up your registry configuration in all of your package.json files individually when e.g. using private registries.
When passed, this flag will alter the default publish process by first publishing all changed packages to a temporary dist-tag (
lerna-temp) and then moving the new version(s) to the default dist-tag (latest).This is not generally necessary, as Lerna will publish packages in topological order (all dependencies before dependents) by default.
Using Lerna? Add a README badge to show it off:
[](https://lernajs.io/)If you prefer some guidance for cli (in case you're about to start using lerna or introducing it to a new team), you might like lerna-wizard. It will lead you through a series of well-defined steps:

