Netlify Adds Day-One Support for Astro 6 With Critical Migration Guidance.

Astro 6 launched March 10, and Netlify shipped same-day support for the framework's latest major release. Developers can upgrade immediately using npx @astrojs/upgrade, which updates Astro, the Netlify adapter, and all official integrations in one command.

The release introduces Vite 7 with a completely redesigned development server, mandatory migration to the Content Layer API, and a Node 22 minimum. Legacy content collections are gone. All projects must now use the Content Layer API, which was introduced in earlier versions but is now required. Node 18 and 20 are no longer supported.

The most significant change involves how Astro handles environment variables. import.meta.env values are now always inlined at build time, which breaks a common pattern developers used for reading secrets at runtime in server-side code.

Previously, developers could use import.meta.env to access environment variables at runtime in server-side routes and API endpoints. Astro 6 now bakes those values directly into the build output during compilation.

Netlify's updated adapter documentation flags the issue explicitly. Developers who need runtime access to environment variables, particularly secrets, must switch to process.env instead:

// Old pattern (no longer works as expected)
const apiKey = import.meta.env.API_KEY;

// New pattern for runtime access
const apiKey = process.env.API_KEY;

Netlify's secret scanning will catch exposed secrets that accidentally get inlined and fail builds before they deploy to production. The platform previously expanded its security features to help teams avoid accidental exposure of sensitive credentials.

The new Vite 7 integration brings performance improvements through a rebuilt development server architecture. Netlify tested the upgrade internally and reports faster build times across projects of varying sizes, though specific benchmarks were not disclosed in the announcement.

The Content Layer API migration affects how projects structure and query content collections. Developers who haven't migrated yet will need to refactor their content architecture as part of the Astro 6 upgrade, since the legacy implementation has been fully removed from the codebase.

Netlify's adapter handles the deployment configuration automatically. Projects using server-side rendering or API routes continue to work without additional changes beyond the environment variable adjustment. The platform's edge network and function runtime support the Node 22 requirement out of the box.

Developers can review the complete upgrade path in Astro's official migration guide and Netlify's framework documentation. The @astrojs/upgrade command handles most dependency updates, but teams should test thoroughly, particularly around environment variable usage and content collection queries.