npm v7 Series - Beta Release! And: SemVer-Major Changes in npm v7


<< Why keep package-lock.json?

A new beta version of npm appears!

tl;dr - Run npm i -g npm@next-7 right now, and tell us about any problems you encounter with it.

This is a big one, you’re going to want to check it out. As with any beta software, it’s likely to still have a few rough edges, but we’re confident that those will be polished down very quickly. Your help finding them will make that process go much faster.

This post outlines the major-version updates (aka “Breaking Changes” in SemVer lingo) in this release. If you’re going to start using npm v7, it would be good to take a look over this list and make sure nothing is going to ruin your day.

Despite a massive overhaul of most of npm’s functionality, we are endeavoring to make npm v7 as low-risk and low-effort as possible, for as many users of npm as we possibly can. Nevertheless, this list is fairly long, because we endeavor to call out a change even if we think the impact is likely minor.

For the massive majority of npm users, where your experience is “install my stuff, do the right thing, let me get back to work”, we are confident this update will be entirely an improvement to your development experience.

On the “Breaking” in “Breaking Changes”

The Semantic Versioning specification precisely defines what constitutes a “breaking” change. In a nutshell, it’s any change that causes a you to change your code in order to start using our code. We hasten to point this out, because a “breaking change” does not mean that something about the update is “broken”, necessarily.

We’re sure that some things likely are broken in this beta, because it’s best to be pessimistic about beta software. But nothing is “broken” on purpose here, and if you find a bug, we’d love for you to let us know so we can get it fixed before the beta tag falls off.

Peer Dependencies

We have identified automatic peerDependencies installation as a potentially disruptive change for many users (albeit one that we are confident is the correct behavior for a package manager), we have some tools to minimize this disruption, based on the feedback we get.

We are confident that resolving package trees such that peerDependencies are properly accounted for is the right thing to do. After all, an error here can result in a production issue that’s very difficult to debug later, especially if it occurs deep in a node_modules tree. However, years of not resolving peerDependencies has allowed many projects to fail to notice these problems.

In order to get unblocked and install your project in spite of peerDependencies conflicts, you can use the --legacy-peer-deps flag at install time. It may be that the disruption is too great to take all at once, and we have to have this flag enabled by default for a while as projects gradually update their conflicting dependencies. Our intent is to let the beta give us some more data points to help make that decision carefully.

Regardless of where we land on installs, the npm ls command will always run with --legacy-peer-deps set to false, so that missing peer dependencies will be highlighted when looking at the package tree. We hope that this will be useful encouragement to get projects to update out of a broken state (or worse, a “works by accident” state).

Beta Schedule

Beta versions of v7 will go out weekly on Tuesdays until everything looks good. We’ll decide to cut a GA release based on stability and getting the last bits of housecleaning done.

What’s Missing From This Beta (Why Not GA?)

We have not yet gotten to 100% test coverage of the npm CLI codebase. As such, there are almost certainly bugs lying in wait. We do have 100% test coverage of most of the commands, and all recently-updated dependencies in the npm stack, so it’s certainly more well-tested than any version of npm before.

There’s still lots of work we need to do in updating the documentation. Prior to a GA release, we’ll be going through all of our documentation with a fine-toothed comb to make sure it’s as accurate and helpful as possible.

That’s about it! It’s ready to use for most purposes, and you should try it out.

Now on to the list of changes.

Programmatic Usage

  • RFC 20 The CLI and its dependencies no longer use the figgy-pudding library for configs. Configuration is done using a flat plain old JavaScript object.
  • The lib/fetch-package-metadata.js module is removed. Use pacote to fetch package metadata.
  • @npmcli/arborist should be used to do most things programmatically involving dependency trees.
  • The onload-script option is no longer supported.
  • The log-stream option is no longer supported.
  • npm.load() MUST be called with two arguments (the parsed cli options and a callback).
  • npm.root alias for npm.dir removed.
  • The package.json in npm now defines an exports field, making it no longer possible to require() npm’s internal modules. (This was always a bad idea, but now it won’t work.)

All Registry Interactions

The following affect all commands that contact the npm registry.

  • referer header no longer sent
  • npm-command header added

All Lifecycle Scripts

The environment for lifecycle scripts (eg, build scripts, npm test, etc.) has changed.

  • RFC 21 Environment no longer includes npm_package_* fields, or npm_config_* fields for default configs. npm_package_json, npm_package_integrity, npm_package_resolved, and npm_command environment variables added.

    (NB: this will change a bit prior to a v7.0.0 GA release)

  • RFC 22 Scripts run during the normal course of installation are silenced unless they exit in error (ie, with a signal or non-zero exit status code), and are for a non-optional dependency.

  • RFC 24 PATH environment variable includes all node_modules/.bin folders, even if found outside of an existing node_modules folder hierarchy.

  • The user, group, uid, gid, and unsafe-perms configurations are no longer relevant. When npm is run as root, scripts are always run with the effective uid and gid of the working directory owner.

  • Commands that just run a single script (npm test, npm start, npm stop, and npm restart) will now run their script even if --ignore-scripts is set. Prior to the GA v7.0.0 release, they will not run the pre/post scripts, however. (So, it’ll be possible to run npm test --ignore-scripts to run your test but not your linter, for example.)

npx

The npx binary was rewritten in npm v7, and the standalone npx package deprecated when v7.0.0 hits GA. npx uses the new npm exec command instead of a separate argument parser and install process, with some affordances to maintain backwards compatibility with the arguments it accepted in previous versions.

This resulted in some shifts in its functionality:

  • Any npm config value may be provided.
  • To prevent security and user-experience problems from mistyping package names, npx prompts before installing anything. Suppress this prompt with the -y or --yes option.
  • The --no-install option is deprecated, and will be converted to --no.
  • Shell fallback functionality is removed, as it is not advisable.
  • The -p argument is a shorthand for --parseable in npm, but shorthand for --package in npx. This is maintained, but only for the npx executable. (Ie, running npm exec -p foo will be different from running npx -p foo.)
  • The --ignore-existing option is removed. Locally installed bins are always present in the executed process PATH.
  • The --npm option is removed. npx will always use the npm it ships with.
  • The --node-arg and -n options are removed.
  • The --always-spawn option is redundant, and thus removed.
  • The --shell option is replaced with --script-shell, but maintained in the npx executable for backwards compatibility.

We do intend to continue supporting the npx that npm ships; just not the npm install -g npx library that is out in the wild today.

Files On Disk

  • RFC 13 Installed package.json files no longer are mutated to include extra metadata. (This extra metadata is stored in the lockfile.)
  • package-lock.json is updated to a newer format, using "lockfileVersion": 2. This format is backwards-compatible with npm CLI versions using "lockfileVersion": 1, but older npm clients will print a warning about the version mismatch.
  • yarn.lock files used as source of package metadata and resolution guidance, if available. (Prior to v7, they were ignored.)

Dependency Resolution

These changes affect install, ci, install-test, install-ci-test, update, prune, dedupe, uninstall, link, and audit fix.

  • RFC 25 peerDependencies are installed by default. This behavior can be disabled by setting the legacy-peer-deps configuration flag.

    BREAKING CHANGE: this can cause some packages to not be installable, if they have unresolveable peer dependency conflicts. While the correct solution is arguably to fix the conflict, this was not forced upon users for several years, and some have come to rely on this lack of correctness. Use the --legacy-peer-deps config flag if impacted.

    See the note above about --legacy-peer-deps.

  • RFC 23 Support for acceptDependencies is added. This can result in dependency resolutions that previous versions of npm will incorrectly flag as invalid.

  • Git dependencies on known git hosts (GitHub, BitBucket, etc.) will always attempt to fetch package contents from the relevant tarball CDNs if possible, falling back to git+ssh for private packages. resolved value in package-lock.json will always reflect the git+ssh url value. Saved value in package.json dependencies will always reflect the canonical shorthand value.

  • Support for the --link flag (to install a link to a globall-installed copy of a module if present, otherwise install locally) has been removed. Local installs are always local, and npm link <pkg> must be used explicitly if desired.

  • Installing a dependency with the same name as the root project no longer requires --force. (That is, the ENOSELF error is removed.)

Workspaces

  • RFC 26 First phase of workspaces support is added. This changes npm’s behavior when a root project’s package.json file contains a workspaces field.

npm update

  • RFC 19 Update all dependencies when npm update is run without any arguments. As it is no longer relevant, --depth config flag removed from npm update.

npm outdated

  • RFC 27 Remove --depth config from npm outdated. Only top-level dependencies are shown, unless --all config option is set.

npm adduser, npm login

  • The --sso options are deprecated, and will print a warning.

npm audit

  • Output and data structure is significantly refactored to call attention to issues, identify classes of fixes not previously available, and remove extraneous data not used for any purpose.

    BREAKING CHANGE: Any tools consuming the output of npm audit will almost certainly need to be updated, as this has changed significantly, both in the readable and --json output styles.

npm dedupe

  • Performs a full dependency tree reification to disk. As a result, npm dedupe can cause missing or invalid packages to be installed or updated, though it will only do this if required by the stated dependency semantics.

  • Note that the --prefer-dedupe flag has been added, so that you may install in a maximally deduplicated state from the outset.

npm fund

  • Human readable output updated, reinstating depth level to the printed output.

npm ls

  • Extraneous dependencies are listed based on their location in the node_modules tree.
  • npm ls only prints the first level of dependencies by default. You can make it print more of the tree by using --depth=<n> to set a specific depth, or --all to print all of them.

npm pack, npm publish

  • Generated gzipped tarballs no longer contain the zlib OS indicator. As a result, they are truly dependent only on the contents of the package, and fully reproducible. However, anyone relying on this byte to identify the operating system of a package’s creation may no longer rely on it.

npm rebuild

  • Runs package installation scripts as well as re-creating links to bins. Properly respects the --ignore-scripts and --bin-links=false configuration options.

npm build, npm unbuild

  • These two internal commands were removed, as they are no longer needed.

npm test

  • When no test is specified, will fail with missing script: test rather than injecting a synthetic echo 'Error: no test specified' test script into the package.json data.

Credits

Huge thanks to the people who wrote code for this update, as well as our group of dedicated Open RFC call participants. Your participation has contributed immeasurably to the quality and design of npm.

<< Why keep package-lock.json?