yarn-deduplicate
Cleans up yarn.lock
by removing duplicates.
This package only works with Yarn v1. Yarn v2 supports package deduplication natively!
A duplicate package is when two dependencies are resolved to a different version, even when a single version matches the range specified in the dependencies. See the Deduplication strategies section for a few examples.
Installation
Install the package globally:
npm install -g yarn-deduplicate
or
yarn global add yarn-deduplicate
This package also works wth npx, so you don't need to install it.
Usage
The most common scenario is to run
yarn-deduplicate yarn.lock
This will use the default strategy to remove duplicated packages in yarn.lock
.
If you do not specify the yarn.lock path, it defaults to yarn.lock
.
Check all available options with:
yarn-deduplicate --help
Duplicated packages
yarn.lock
contains a list of all the dependencies required by your project (including transitive
dependencies), and the actual package version installed to satisfy those dependencies.
For the context of this project, a "duplicated package" is a package that appears on multiple nodes of the dependency tree with overlapping version ranges but resolved to different versions.
For example, imagine that your project directly depends on lodash
and babel
, and babel
depends
on lodash
as well. Specifically, your project depends on lodash@^1.0.0
and babel
depends on
lodash@^1.1.0
. Because how the resolution algorithm works in Yarn, you might end up with two
different copies of lodash
(for example, version 1.0.1
and 1.2.0
) in your project, even when
1.2.0
will suffice to satisfy both requirements for lodash
. That's a "duplicated package".
It is important to note that we do not consider duplicated packages when the version ranges don't
overlap. For example, if your project depends on underscore@^1.0.0
and underscore@^2.0.0
. Your
project will end up with two versions of underscore
, and yarn-deduplicate
won't change that.
When using yarn-deduplicate
remember that it will change your dependency tree. There are
certain code paths that now will run with a different set of dependencies. It is highly recommended
that you review each change to yarn.lock
. If the change is too big, use the flag --packages
to
deduplicate them gradually.
Why is this necessary?
Yarn documentation seems to suggest this package shouldn't be necessary. For example, in https://classic.yarnpkg.com/en/docs/cli/dedupe/, it says
The dedupe command isn’t necessary.
yarn install
will already dedupe.
This is, however, not exactly true. There are cases where yarn will not deduplicate existing packages. For example, this scenario:
-
Install
libA
. It depends onlibB ^1.1.0
. At this point, the latest version oflibB
is1.1.2
, so it gets installed as a transitive dependency in your repo -
After a few days, install
libC
. It also depends onlibB ^1.1.0
. But this time, the latestlibB
version is1.1.3
.
In the above scenario, you'll end up with libB@1.1.2
and libB@1.1.3
in your repo.
Find more examples in:
Deduplication strategies
--strategy <strategy>
highest
will try to use the highest installed version. For example, with the following
yarn.lock
:
library@^1.1.0:
version "1.2.0"
library@^1.2.0:
version "1.2.0"
library@^1.3.0:
version "1.3.0"
It will deduplicate library@^1.1.0
and library@^1.2.0
to 1.3.0
fewer
will try to minimize the number of installed versions by trying to deduplicate to the
version that satisfies most of the ranges first. For example, with the following yarn.lock
:
library@*:
version "2.0.0"
library@>=1.1.0:
version "3.0.0"
library@^1.2.0:
version "1.2.0"
It will deduplicate library@*
and library@>=1.1.0
to 1.2.0
.
Note that this may cause some packages to be downgraded. Be sure to check the changelogs between all versions and understand the consequences of that downgrade. If unsure, don't use this strategy.
It is not recommended to use different strategies for different packages. There is no guarantee that
the strategy will be honored in subsequent runs of yarn-deduplicate
unless the same set of flags
is specified again.
Progressive deduplication
--packages <package1> <package2> <packageN>
Receives a list of packages to deduplicate. It will ignore any other duplicated package not in the
list. This option is recommended when the number of duplicated packages in yarn.lock
is too big to
be easily reviewed by a human. This will allow for a more controlled and progressive deduplication
of yarn.lock
.
--scopes <scope1> <scope2> <scopeN>
Receives a list of scopes to deduplicate. It will ignore any other duplicated package not in the
list. This option is recommended when deduplicating a large number of inter-dependent packages from
a single scope, such as @babel. This will allow for a more controlled and progressive deduplication
of yarn.lock
without specifying each package individually.
Excluding packages
--exclude <package1> <package2> <packageN
--exclude-scopes <scope1> <scope2> <scopeN>
With these commands you can exclude certain packages/scopes from the deduplication process. This is specially useful if you want to apply a different strategy for a scope, for example.
Pre-release versions
By default, yarn-deduplicate
will only match pre-release versions if they share they share the
same major
, minor
and patch
versions (example: ^1.2.3-alpha.1
and 1.2.3-alpha.2
can be
deduplicated, but ^1.2.3
and 1.2.4-alpha.1
can't). This matches the behaviour of
semver.
To change this behaviour you can use the flag --includePrerelease
. This will treat all pre-release
versionas as if they were normal versions (^1.2.3
and 1.2.4-alpha.1
can be deduplicated).
Usage in CI
This tool can be used as part of a CI workflow. Adding the flag --fail
will force the process to
exit with status 1 if there are duplicated packages. Example:
# Print the list of duplicated packages and exit with status 1
yarn-deduplicate --list --fail
# Deduplicate yarn.lock and exit with status 1 if changes were required
yarn-deduplicate --fail
Migration guide
From 2.x to 3.x
In this version we have adopted variadic arguments from commander.js. These are the equivalent commands:
#Old
yarn-deduplicate --packages libA,libB
yarn-deduplicate --scopes @scopeA,@scopeB
yarn-deduplicate --exclude libA,libB
#New
yarn-deduplicate --packages libA libB
yarn-deduplicate --scopes @scopeA @scopeB
yarn-deduplicate --exclude libA libB
A consequence of this change is that if you were using one or more of the affected options (
--packages
, --scopes
or --exclude
) and a custom path for yarn.lock
, you need to use --
to "stop" package/scope/exclude parsing:
yarn-deduplicate --packages libA libB -- path/to/yarn.lock
From 0.x to 1.x
In this version we have renamed the project and refactored the CLI. These are the equivalent commands:
Installation
# Old
npm install -g yarn-tools
# New
npm install -g yarn-deduplicate
List duplicates
# Old
yarn-tools list-duplicates path/to/yarn.lock
# New
yarn-deduplicate --list path/to/yarn.lock
Deduplicate yarn.lock
# Old
yarn-tools fix-duplicates path/to/yarn.lock > tmp
mv tmp path/to/yarn.lock
# New
yarn-deduplicate path/to/yarn.lock
Limit packages to deduplicate yarn.lock
# Old
yarn-tools fix-duplicates path/to/yarn.lock package1 package2
# New
yarn-deduplicate --packages package1,package2 path/to/yarn.lock
License
Copyright (c) 2022 Sergio Cinos and others. Apache 2.0 licensed, see LICENSE.txt file.