CI/CD for a SvelteKit + Vercel App with GitHub Actions

Check, test, build, and deploy your SvelteKit app to Vercel automatically.

SvelteKit with adapter-vercel targets Vercel functions and edge. This recipe runs svelte-check and Vitest, then deploys with the Vercel CLI so PRs get previews and main goes to production.

What the pipeline does

install deps with npm ci
sync types with svelte-kit sync
type-check with svelte-check
test with vitest run
deploy with the Vercel CLI

The workflow

svelte-kit sync generates the .svelte-kit types before svelte-check. The Vercel CLI builds and deploys; --prod is gated on the default branch.

.github/workflows/ci.yml

name: CI
on:
  push:
    branches: [main]
  pull_request:
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 20
          cache: npm
      - run: npm ci
      - run: npx svelte-kit sync
      - run: npx svelte-check --tsconfig ./tsconfig.json
      - run: npx vitest run
      - name: Deploy
        run: |
          npx vercel pull --yes --environment=production --token=${{ secrets.VERCEL_TOKEN }}
          npx vercel build --prod
          npx vercel deploy --prebuilt --prod --token=${{ secrets.VERCEL_TOKEN }}
        if: github.ref == 'refs/heads/main'

Caching and speed

cache: npm restores installs and persisting .svelte-kit with actions/cache speeds type generation. svelte-check plus Vitest run fast, and on cheaper managed runners such as Latchkey (around 69% cheaper than GitHub-hosted) the whole pipeline stays inexpensive, with auto-retry covering Vercel API blips.

Deploying

adapter-vercel packages routes as Vercel functions. vercel deploy --prebuilt ships the prebuilt output; drop the if guard and --prod to give every PR a preview URL via vercel deploy.

Key takeaways

Run svelte-kit sync before svelte-check to generate route types.
adapter-vercel turns routes into Vercel functions and edge handlers.
Gate vercel --prod on the main branch; PRs get preview deploys.