Signed Npm Version Bumps

by Anton Semjonov

Table of Contents


For a while now I’ve been using Visual Studio Code for a few JavaScript / TypeScript projects. Most of these projects come with a package.json file, which documents various aspects of the project. A tiny example of such a file:

  "name": "foo",
  "version": "1.2.3",
  "description": "A packaged foo fooer for fooing foos",
  "main": "foo.js"

npm version

There’s that interesting property version. In conjunction with the npm version command it allows for very easy version bumping with automatic tagging. There are three useful keywords for that command to bump semver-compliant versions: major, minor and patch. You can also set a specific version directly but refer to the documentation on npm for details. Observe:

/tmp/tmp.tHu9SBWQcl $ git init
Initialized empty Git repository in /tmp/tmp.tHu9SBWQcl/.git/
/tmp/tmp.tHu9SBWQcl $ echo '{ "version": "0.0.0" }' > package.json
/tmp/tmp.tHu9SBWQcl $ npm version patch
/tmp/tmp.tHu9SBWQcl $ npm version patch
/tmp/tmp.tHu9SBWQcl $ npm version minor
/tmp/tmp.tHu9SBWQcl $ npm version patch
/tmp/tmp.tHu9SBWQcl $ npm version v0.4.0
/tmp/tmp.tHu9SBWQcl $ npm version major
/tmp/tmp.tHu9SBWQcl $ git log
8138e90 2017-01-14 (15 seconds ago) 1.0.0
c8f8930 2017-01-14 (21 seconds ago) 0.4.0
ba7fc59 2017-01-14 (36 seconds ago) 0.1.1
3c7d08b 2017-01-14 (38 seconds ago) 0.1.0
00a15b7 2017-01-14 (42 seconds ago) 0.0.2
ff52b31 2017-01-14 (44 seconds ago) 0.0.1

signed tags

Git also supports signed tags and commits. To make use of that, first set your preferred GPG Key ID with git config:

/tmp/tmp.tHu9SBWQcl $ gpg -K demo
sec   rsa2048 2017-01-14 [SC] [expires: 2019-01-14]
uid           [ultimate] Demouser <>
ssb   rsa2048 2017-01-14 [E] [expires: 2019-01-14]

/tmp/tmp.tHu9SBWQcl $ git config --global user.signingkey EDB34D547A63C77223A2832C7FDA8637DAC8A82E

Following the above guide on you could now sign your commits with git commit -S [...] or your tags with git tag -s [...]. Wouldn’t it be beautiful to combine npm’s version bumping with signing your tags?

Behold! There is npm’s sign-git-tag option. You could also set this option globally with npm config set sign-git-tag true. Or leave it at false and set the flag with every npm command: npm version [...] --sign-git-tag.

After reading this issue on GitHub, I found out that npm’s option parser also allows for abbreviated options, if there is no other option conflicting. This appears to be the case with --sign!

signed version bumps

In conclusion, we can now bump our project’s version and sign the new tag automatically with npm version [...] --sign, which I think is short enough to not require a global setting.

/tmp/tmp.tHu9SBWQcl $ npm version minor --sign
[pinentry dialogue pops up]
/tmp/tmp.tHu9SBWQcl $ git tag -v v1.1.0
object cde27091c4e76438086a91fe0659b6816665d0ae
type commit
tag v1.1.0
tagger Demouser <> 1484407322 +0100

gpg: Signature made Sat 14 Jan 2017 16:22:02 CET
gpg:                using RSA key EDB34D547A63C77223A2832C7FDA8637DAC8A82E
gpg: Good signature from "Demouser <>" [ultimate]