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An alternative package manager for Node.
-
Concurrent Installations -
iedinstalls sub-dependencies in parallel. This means that the download of a dependency might have been completed before that of its parent or any of its siblings even started. -
Correct Caching - Downloaded packages are being cached locally. Similarly to the entry dependencies stored in
node_modules, they are being identified by their checksums. Therefore we can guarantee the consistency of the cache itself without (manually) invalidating dependencies (e.g. due to overridden version numbers). -
node_modulesas CAS - Packages are always being referenced by their SHA-1 checksums. Therefore anode_modulesdirectory can be considered to be a Content Addressable Storage, meaning that packages are being identified by their contents, not by arbitrary identifiers, such as package names that are not guaranteed to be unique across different registries. -
Flat
node_modules- Due to the CAS-based design, conflicts due to naming collisions are more or less impossible. Therefore all dependencies can be stored in a flat directory structure. Circular dependencies and dependencies on different versions of the same packages are still being handled correctly. -
Guaranteed uniqueness - Since the directory in which a specific package is being stored is determined by its shasum, identical packages can't conflict due to their location in the file system itself. This also means that the same dependency won't be installed more than once. Dependencies don't need to be explicitly declared as
peerDependencies, since shared sub-dependencies are the default, not an option. -
Atomic installs - The atomicity of installs can be ensured on a package-level. "In progress" downloads are being stored in
node_modules/.tmpand moved intonode_modulesonce their download has been completed. In order to prevent deadlocks, packages that have circular dependencies are exempt from this limitation. In most cases however, thenode_modulesdirectory is consistent at any given point in time during the main installation procedure. -
Package names as links - While packages are being referenced by their shasum internally, they can still be required via their human-readable equivalent name. Package names themselves are simply symbolic links to the actual content-addressed package itself. A nice side-effect of this design is that in contrast to other package managers, you can not accidentally require a sub-dependency that hasn't been installed as such.
-
Semantic Versioning - Semantic version numbers are being resolved correctly.
-
Arbitrary package groups - Packages can be grouped into "package groups", such as
dependenciesanddevDependencies. Dependencies can be installed exclusively based on the group they are in.
Under the hood, ied maintains an "object database", similar to git. Instead
of storing packages by some arbitrary name, a SHA1-checksum is being generated
to approximate their contents. The checksums can not only be used for
guaranteeing a certain level of trust and consistency, but they also simplify
the algorithm through which dependencies are being managed.
The algorithm through which packages are being installed guarantees consistency through atomic installs. The installation of a package either fails or succeeds, but at no point in time can a dependency itself be required without having its own sub-dependencies installed (with the exception of shared circular dependencies).
The checksum of a package is based on the contents of the package itself, not of its sub-dependencies. Therefore the validity of a package can be verified by hashing the package itself. Subsequent dependency updates have no effect of the generated checksum.
Since node_modules is essentially a file-system based content addressable
storage, multiple versions of the same package can co-exist in the same
project. In order to expose dependencies via CommonJS, symbolic links are being
created that reference a specific version of the package. This has multiple
advantages:
-
Undeclared dependencies that have been installed as sub-dependencies of "direct" dependencies are unlikely to be required "accidentally".
-
There is no need to "manually" (as in additionally to the installation procedure itself) de-duplicate the dependency graph. As long as the uniqueness of filenames itself can be guaranteed on an OS-level, it is impossible to install the same package twice. This does not prevent users from installing different versions of the same dependency as long as the content is different (whereas a different version declared in the
package.jsoncounts as different contents). -
Shorter pathnames and less problems due to OS-level limitations (as in Windows where the maximum path length is limited).
-
Additional application-level startup performance improvements.
requireneeds to traverse less directories. A limited number of symbolic links need to be followed. This performance improvement is primarily useful for continuously running tests, where startup time is actually noticeable for larger test suits.
The used directory structure is primarily optimized for reducing the amount of IO interaction with the file system during subsequent installations and guaranteeing the consistency of installed packages.
A consequence of the
require.resolve
algorithm used by Node, all packages need to be stored in a project-level
node_modules directory. This directory is completely flat on a package-level,
meaning that there are no nested packages inside it.
Instead each package is being stored in its content-addressed directory. Such a directory has two sub-directories:
-
package - This is where the unpacked package contents is being stored. At no point in time will this directory be modified. This enables us to verify the integrity of the package at a later point in time by comparing the actual checksum to the one defined by other dependents or registries.
-
node_modules - Sub-dependencies of the dependency installed in
packageare being referenced by symbolic links innode_modulesof the package itself.require.resolvewill fall-back to this level after failing to locate a dependency inpackage. This means checked in dependencies are still supported, provided that their sub-dependencies are also available (anywhere in the dependency graph).
On a project level, the node_modules directory contains the fetched packages,
installed dependencies and links that expose the packages to user-land via
require.
A comparison of sample directory structures produced by ied, npm 2 and npm 3 is available as a GitHub Gist.
The original idea was to implement npm's pre-v3 install algorithm in as few
lines as possible. This goal was achieved in
c4ba56f.
Currently the main goal of this project is to provide a more performant alternative to npm.
The easiest way to install ied is using npm:
npm i -g ied
Alternatively you can also "bootstrap" ied. After an initial installation via npm, ied will install its own dependencies:
git clone https://github.com/alexanderGugel/ied ied && cd $_ && make install
The goal of ied is to support ~ 80 per cent of the npm commands that one uses
on a daily basis. Feature parity with npm other than with its installation
process itself is not an immediate goal. Raw performance is the primary concern
during the development process.
A global configuration can be supplied via environment
variables. NODE_DEBUG can be used in order to debug specific sub-systems. The
progress bar will be disabled in that case.
Although run-script is supported, lifecycle scripts are not.
At this point in time, the majority of the command API is self-documenting. More extensive documentation will be available once the API is stabilized.
A high-level USAGE help is also supplied. The main goal is to
keep the API predictable for regular npm-users. This means certain flags, such
as for example --save, --save-dev, --save-optional, are supported.
ied is a package manager for Node.
Usage:
ied [command] [arguments]
The commands are:
install fetch packages and dependencies
run run a package.json script
shell enter a sub-shell with augmented PATH
ping check if the registry is up
config print the used config
init initialize a new package
link link the current package or into it
unlink unlink the current package or from it
start runs `ied run start`
stop runs `ied run stop`
build runs `ied run build`
test runs `ied run test`
Flags:
-h, --help show usage information
-v, --version print the current version
-S, --save update package.json dependencies
-D, --save-dev update package.json devDependencies
-O, --save-optional update package.json optionalDependencies
-r, --registry use a custom registry
(default: http://registry.npmjs.org/)
-b, --build execute lifecycle scripts upon completion
(e.g. postinstall)
Example:
ied install
ied install <pkg>
ied install <pkg>@<version>
ied install <pkg>@<version range>
Can specify one or more: ied install semver@^5.0.1 tape
If no argument is supplied, installs dependencies from package.json.
Sub-commands can also be called via their shorthand aliases.
README: https://github.com/alexanderGugel/ied
ISSUES: https://github.com/alexanderGugel/ied/issues
To run the test suite, run npm test. The test suite mocks all HTTP requests,
with fixtures cached inside fixtures/generated/. If you make new tests that
perform HTTP requests, it'll be saved there.
npm test
Some ideas and (upcoming) features of ied are heavily inspired by
Nix, a purely functional package manager.
Licensed under the MIT license. See LICENSE.
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