astro/CONTRIBUTING.md

Contributor Manual

We welcome contributions of any size and skill level. As an open source project, we believe in giving back to our contributors and are happy to help with guidance on PRs, technical writing, and turning any feature idea into a reality.

Tip for new contributors: Take a look at https://github.com/firstcontributions/first-contributions for helpful information on contributing

Quick Guide

Prerequisite

node: "^14.18.0 || >=16.12.0"
pnpm: "^7.5.0"
# otherwise, your build will fail

Setting up your local repo

Astro uses pnpm workspaces, so you should always run pnpm install from the top-level project directory. running pnpm install in the top-level project root will install dependencies for astro, and every package in the repo.

git clone && cd ...
pnpm install
pnpm run build

In #2254 a .git-blame-ignore-revs file was added to ignore repo-wide formatting changes. To improve your experience, you should run the following command locally.

git config --local blame.ignoreRevsFile .git-blame-ignore-revs

To automatically handle merge conflicts in pnpm-lock.yaml, you should run the following commands locally.

pnpm add -g @pnpm/merge-driver
pnpx npm-merge-driver install --driver-name pnpm-merge-driver --driver "pnpm-merge-driver %A %O %B %P" --files pnpm-lock.yaml

Development

# starts a file-watching, live-reloading dev script for active development
pnpm run dev
# build the entire project, one time.
pnpm run build

Debugging Vite

You can debug vite by prefixing any command with DEBUG like so:

DEBUG=vite:* astro dev        # debug everything in Vite
DEBUG=vite:[name] astro dev   # debug specific process, e.g. "vite:deps" or "vite:transform"

Running tests

# run this in the top-level project root to run all tests
pnpm run test
# run only a few tests, great for working on a single feature
# (example - `pnpm run test:match "RSS"` runs `astro-rss.test.js`)
pnpm run test:match "$STRING_MATCH"

E2E tests

Certain features, like HMR and client hydration, need end-to-end tests to verify functionality in the dev server. Playwright is used to test against the dev server.

# run this in the top-level project root to run all E2E tests
pnpm run test:e2e
# run only a few tests, great for working on a single feature
# (example - `pnpm run test:e2e:match "Tailwind CSS" runs `tailwindcss.test.js`)
pnpm run test:e2e:match "$STRING_MATCH"

When should you add E2E tests?

Any tests for astro build output should use the main mocha tests rather than E2E - these tests will run faster than having Playwright start the astro preview server.

If a test needs to validate what happens on the page after it's loading in the browser, that's a perfect use for E2E dev server tests, i.e. to verify that hot-module reloading works in astro dev or that components were client hydrated and are interactive.

Other useful commands

# auto-format the entire project
# (optional - a GitHub Action formats every commit after a PR is merged)
pnpm run format

# lint the project
# (optional - our linter creates helpful warnings, but not errors.)
pnpm run lint

Making a Pull Request

When making a pull request, be sure to add a changeset when something has changed with Astro. Non-packages (examples/*) do not need changesets.

pnpm exec changeset

Running benchmarks

We have benchmarks to keep performance under control. You can run these by running (from the project root):

pnpm run benchmark --filter astro

Which will fail if the performance has regressed by 10% or more.

To update the times cd into the packages/astro folder and run the following:

node test/benchmark/build.bench.js --save
node test/benchmark/dev.bench.js --save

Which will update the build and dev benchmarks.

Code Structure

Server-side rendering (SSR) can be complicated. The Astro package (packages/astro) is structured in a way to help think about the different systems.

• components/: Built-in components to use in your project (e.g. import Code from 'astro/components/Code.astro')
• src/: Astro source
  • @types/: TypeScript types. These are centralized to cut down on circular dependencies
  • cli/: Code that powers the astro CLI command
  • core/: Code that executes in the top-level scope (in Node). Within, you’ll find code that powers the astro build and astro dev commands, as well as top-level SSR code.
  • runtime/: Code that executes in different scopes (i.e. not in a pure Node context). You’ll have to think about code differently here.
    • client/: Code that executes in the browser. Astro’s partial hydration code lives here, and only browser-compatible code can be used.
    • server/: Code that executes inside Vite’s SSR. Though this is a Node environment inside, this will be executed independently from core/ and may have to be structured differently.
  • vite-plugin-*/: Any Vite plugins that Astro needs to run. For the most part, these also execute within Vite similar to src/runtime/server/, but it’s also helpful to think about them as independent modules. Note: at the moment these are internal while they’re in development

Thinking about SSR

There are 3 contexts in which code executes:

• Node.js: this code lives in src/core/.
• Inside Vite: this code lives in src/runtime/server/.
• In the browser: this code lives in src/runtime/client/.

Understanding in which environment code runs, and at which stage in the process, can help clarify thinking about what Astro is doing. It also helps with debugging, for instance, if you’re working within src/core/, you know that your code isn’t executing within Vite, so you don’t have to debug Vite’s setup. But you will have to debug vite inside runtime/server/.

Releasing Astro

Note: Only core maintainers (L3+) can release new versions of Astro.

The repo is set up with automatic releases, using the changeset GitHub action & bot.

To release a new version of Astro, find the Version Packages PR, read it over, and merge it.

Releasing PR preview snapshots

Our release tool changeset has a feature for releasing "snapshot" releases from a PR or custom branch. These are npm package publishes that live temporarily, so that you can give users a way to test a PR before merging. This can be a great way to get early user feedback while still in the PR review process.

To run changeset version locally, you'll need to create a GitHub personal access token and set it as a GITHUB_TOKEN environment variable.

To release a snapshot, run the following locally:

# Notes:
# - YYY should be a keyword to identify this release. Ex: `--snapshot routing` & `--tag next--routing`
# - Use npm/npx instead of pnpm, since npm handles registry login, authentication and publishing.
# - Adding GITHUB_TOKEN in the command adds that token to your bash history. Set a short expiration!

# 1: Tag the new release versions
GITHUB_TOKEN=XXX npx changeset version --snapshot YYY
# 2: Review the diff, and make sure that you're not releasing more than you need to.
git checkout -- examples/
# 3: Release
npm run release --tag next--YYY
# 4: If you're satisfied, you can now throw out all local changes
git reset --hard

By default, every package with a changeset will be released. If you only want to target a smaller subset of packages for release, you can consider clearing out the .changesets directory to replace all existing changesets with a single changeset of only the packages that you want to release. Just be sure not to commit or push this to main, since it will destroy existing changesets that you will still want to eventually release.

Full documentation: https://github.com/atlassian/changesets/blob/main/docs/snapshot-releases.md

Releasing astro@next (aka "prerelease mode")

Sometimes, the repo will enter into "prerelease mode". In prerelease mode, our normal release process will publish npm versions under the next dist-tag, instead of the default latest tag. We do this from time-to-time to test large features before sharing them with the larger Astro audience.

While in prerelease mode, follow the normal release process to release astro@next instead of astro@latest. To release astro@latest instead, see Releasing astro@latest while in prerelease mode.

Full documentation: https://github.com/atlassian/changesets/blob/main/docs/prereleases.md

Entering prerelease mode

If you have gotten permission from the core contributors, you can enter into prerelease mode by following the following steps:

• Run: pnpm exec changeset pre enter next in the project root
• Create a new PR from the changes created by this command
• Review, approve, and more the PR to enter prerelease mode.
• If successful, The "Version Packages" PR (if one exists) will now say "Version Packages (next)".

Exiting prerelease mode

Exiting prerelease mode should happen once an experimental release is ready to go from npm install astro@next to npm install astro. Only a core contributor run these steps. These steps should be run before

• Run: pnpm exec changeset pre exit in the project root
• Create a new PR from the changes created by this command.
• Review, approve, and more the PR to enter prerelease mode.
• If successful, The "Version Packages (next)" PR (if one exists) will now say "Version Packages".

Releasing astro@latest while in prerelease mode

When in prerelease mode, the automatic PR release process will no longer release astro@latest, and will instead release astro@next. That means that releasing to latest becomes a manual process. To release latest manually while in prerelease mode:

1. In the code snippets below, replace 0.X with your version (ex: 0.18, release/0.18, etc.).
2. Create a new release/0.X branch, if none exists.
3. Point release/0.X to the latest commit for the v0.X version.
4. git cherry-pick commits from main, as needed.
5. Make sure that all changesets for the new release are included. You can create some manually (via pnpm exec changeset) if needed.
6. Run pnpm exec changeset version to create your new release.
7. Run pnpm exec release to publish your new release.
8. Run git push && git push --tags to push your new release to GitHub.
9. Run git push release/0.X:latest to push your release branch to latest.
10. Go to https://github.com/withastro/astro/releases/new and create a new release. Copy the new changelog entry from https://github.com/withastro/astro/blob/latest/packages/astro/CHANGELOG.md.
11. Post in Discord #announcements channel, if needed!

Documentation

Help us make docs.astro.build as accurate and easy-to-use as possible. Contributing to documentation can be a great way to get involved with open source development without having to code.

Head over to the withastro/docs repo to get involved!