Creating Github Releases With Lerna

— 5 minute read

Reducing the number of manual steps needed to get code live is a good thing. This is how I create Github releases from the CI process.

Lerna permalink

Lerna is a tool to manage a monorepo. It can automate releases on Github when the version of a package changes, which is one less task to perform manually.

Circle CI permalink

Circle is a continuous integration solution. In this scenario, Circle is configured to run the test suite for each component after a commit. Once the tests pass, Lerna will increment the version number of the component, using the Conventional Commits specification

Creating a release permalink

Circle Config permalink

Here is a workflow definition with two discrete jobs. The first runs the tests; the second runs lerna version against the desired components.

version: 2.1
orbs:
node: circleci/node@1.1.6
jobs:
build-and-test:
executor:
name: node/default
docker:
- image: circleci/node:latest-browsers
resource_class: small
steps:
- checkout
- node/with-cache:
steps:
- run: npm install
- run: npm test

release:
docker:
- image: circleci/node
resource_class: small
steps:
- checkout
- node/with-cache:
steps:
- add_ssh_keys:
fingerprints:
- "F1:NG:3R:PR:1N:T"
- run: npx lerna bootstrap --hoist --ci
- run: npx lerna version --no-private --conventional-commits --create-release github --yes

workflows:
build-and-test:
jobs:
- build-and-test
- release:
filters:
branches:
only: main
requires:
- build-and-test

All the interesting work is contained within this instruction:

npx lerna version --no-private --conventional-commits --create-release github --yes

Lerna will increment the version of public packages using the Conventional Commits spec, before creating a Github release, and it won't need any prompting to do so.

Creating a deploy key permalink

In order to modify the project repository, Circle will need an SSH key with write access: a "deploy key". The public key is added from the project's settings/keys screen on Github; the private half is added to Circle via Project Settings -> SSH Keys. You'll know if you got it right, because you'll avoid the following:

lerna ERR! lerna ERROR: The key you are authenticating with has been marked as read only.
lerna ERR! lerna fatal: Could not read from remote repository.
lerna ERR! lerna
lerna ERR! lerna Please make sure you have the correct access rights
lerna ERR! lerna and the repository exists.
lerna ERR! lerna

Adding an access token permalink

While the machine might be authenticated, Lerna will need to identify itself as working with the correct permissions. Thus the addition of GH_TOKEN available to it. A new access token can be created from within Github

Publishing the release permalink

When a build goes green on the main branch, a new release will appear automatically on Github. The release notes will be filled automatically, and the changelog for each package will have been updated at the same time. There does appear to be a slight bug with the version number. My understanding is that fix commits will increment the patch number when using semantic versioning, but the component has increased from 0.2.0 to 0.2.1 with a single chore commit…

Next steps permalink

Lerna's publish command works the same as version, but automates publishing to NPM.