Manypkg

Manypkg is a linter for package.json files in Yarn, Bolt or pnpm monorepos.

Install

yarn add @manypkg/cli

Usage

manypkg check

manypkg check runs all of the checks against your repo, logs any errors and exits with a code

manypkg fix

manypkg fix runs all of the checks against your repo and fixes any of problems that can be fixed.

manypkg run <partial package name or directory> <script>

manypkg run executes scripts for packages within a monorepo.

As an example, let's say there are two packages: @project/package-a at packages/pkg-a and @project/package-b at packages/pkg-b which both have a start script, manypkg run can be used like this:

yarn manypkg run pkg-a start
yarn manypkg run a start
yarn manypkg run package-a start
yarn manypkg run @project/package-a start
yarn manypkg run packages/pkg-a start
yarn manypkg run package-b start
yarn manypkg run b start

The following wouldn't work though because the package and pkg aren't unique among the package names/directories:

yarn manypkg run package start
yarn manypkg run pkg start

In order to target a package with a name that is a substring of another (for example, @project/package-a at packages/pkg-a and @project/package-a-1 at packages/pkg-a-1), use the exact package or directory name:

yarn manypkg run @project/package-a start
yarn manypkg run packages/pkg-a start

manypkg exec <cli command>

manypkg exec executes a command for all packages within a monorepo.

As an example, let's say there are two packages which both have a dist dir, manypkg exec can be used like this:

yarn manypkg exec rm -rf dist

Dictionary

• private package - A package that has private: true/is not published. It does not refer to a package published to a private registry here.
• internal package - A package that is local/in the repo
• external package - A package that is from a registry like npm
• range - A node-semver range
• highest range - The range which has the highest lower bound. If there are multiple ranges with the same highest lower bound, the range with the highest upper bound is the highest range.

Checks

External mismatch

The ranges for all dependencies(excluding peerDependencies) on external packages should exactly match(===). It's important to note that this check does not enforce that only a single version of an external package is installed, only that two versions of an external package will never be installed because they're specified as dependencies of internal packages.

Why it's a rule

So that only a single version of an external package will be installed because having multiple versions of the same package can cause confusion and bundle size problems especially with libraries like React that require there to only be a single copy of the library.

How it's fixed

The most commonly used range of the dependency is set as the range at every non-peer dependency place it is depended on. If for some reason, every range is used the same amount of times, they'll all be fixed to the highest version.

Examples

{
  "name": "@manypkg-example/repo",
  "version": "1.0.0",
  "workspaces": ["packages/*"]
}

{
  "name": "@manypkg-example/pkg-a",
  "version": "1.0.0",
  "dependencies": {
    "some-external-package": "1.0.0"
  }
}

{
  "name": "@manypkg-example/pkg-b",
  "version": "1.0.0",
  "dependencies": {
    "some-external-package": "2.0.0"
  }
}

{
  "name": "@manypkg-example/pkg-c",
  "version": "1.0.0",
  "dependencies": {
    "some-external-package": "1.0.0"
  }
}

{
  "name": "@manypkg-example/repo",
  "version": "1.0.0",
  "workspaces": ["packages/*"]
}

{
  "name": "@manypkg-example/pkg-a",
  "version": "1.0.0",
  "dependencies": {
    "some-external-package": "1.0.0"
  }
}

{
  "name": "@manypkg-example/pkg-b",
  "version": "1.0.0",
  "dependencies": {
    "some-external-package": "1.0.0"
  }
}

Ignoring this rule

There are some cases where you might want to intentionally have conflicts between versions. To do this, you can use something that isn't a valid semver range instead of a range such as a git url or etc. If you'd like a conflicting version of an npm package, you can use npm:pkg-name@your-range-here instead of just a range and it will be ignored.

Note: Do this with care, having different versions of the same package can lead to strange bugs

Internal mismatch

The ranges for all regular dependencies, devDependencies and optionalDependencies(not peerDependencies) on internal packages should include the version of the internal package.

Why it's a rule

So that an internal package that depends on another internal package will always get the local version of the internal package rather than a version from the registry because installing internal packages from the registry can be very confusing since you generally expect to get the local version when you depend on an internal package.

How it's fixed

If the range is a caret range or a tilde range with no other comparators, the range is set as a caret or tilde range respectively with the version of the internal package. If it is any other range, the range is set to the exact version of the internal package.

Invalid dev and peer dependency relationship

All peerDependencies should also be specified in devDependencies and the range specified in devDependencies should be a subset of the range for that dependency in peerDependencies.

Why it's a rule

This is so that peerDependencies are available in the package during development for testing and etc.

How it's fixed

The range for the dependency specified in peerDependencies is added to devDependencies unless the package is already a non-peer dependency elsewhere in the repo in which, that range is used instead.

Root has devDependencies

The root package should not have any devDependencies, instead all dependencies should be in dependencies

Why it's a rule

The root package.json of a monorepo is not published so whether a dependency is in devDependencies or dependencies does not make a difference and having one place to put dependencies in the root means that people do not have to arbitrarily decide where a dependency should go every time they install one.

How it's fixed

All devDependencies in the root package.json are moved to dependencies.

Multiple dependency types

A dependency shouldn't be specified in more than one of dependencies, devDependencies or optionalDependencies.

How it's fixed

The dep is removed from devDependencies or optionalDependencies if it's also in dependencies, if it's in devDependencies and optionalDependencies, it is removed from dependencies.

Invalid package name

There are rules from npm about what a package name can be and a package will fail to publish if those rules are not met.

Why it's a rule

All packages will be published together so some packages may depend on a package which can't be published. Checking for invalid package names prevents this kind of publish failure.

How it's fixed

This requires manual fixing as automatically fixing this may lead to valid but incorrect package names.

Unsorted dependencies

Dependencies in the dependency fields(dependencies, devDependencies, peerDependencies, optionalDependencies) should be sorted alphabetically.

Why it's a rule

When you add a package with yarn add or etc. dependencies are sorted, and this can cause confusing diffs if the dependencies were not previously sorted.

How it's fixed

This is fixed by sorting deps by key alphabetically.

Incorrect repository field

If a GitHub repo URL is in the repository field in the root package.json, all of the packages should have a repository field which goes into the directory of the package.

Why it's a rule

Having a repository field is helpful so there is a link to the source of a package on npm but setting that field on every package and making sure it's correct is error prone and time consuming.

How it's fixed

This is fixed by setting the correct URL.

workspace: protocol required

If "workspaceProtocol": "require" is set in the manypkg config in the root package.json, all dependencies on internal packages are required to use the workspace: protocol.

Why it's a rule

If you want to enforce the usage of the workspace: protocol.

How it's fixed

Dependencies are changed to workspace:^. Anything else is also allowed after the workspace: though.

License

Copyright (c) 2023 Thinkmill Labs Pty Ltd. Licensed under the MIT License.