sveltekit-adapter-cloudflare

A drop-in replacement for @sveltejs/adapter-cloudflare that adds support for Cloudflare platform extensions beyond the generated SvelteKit fetch worker.

About this fork

This is a fork of @sveltejs/adapter-cloudflare that adds support for a user-owned Cloudflare platform file. If you do not use one, it behaves like the upstream adapter.

This was requested upstream multiple times and at least partly explored there, but never landed in the official adapter. I also got tired of copying the same handler wiring from project to project — and later, of bending over backwards to get Durable Objects to work alongside it. This fork takes a narrower version of "own the worker": SvelteKit still owns fetch, and the user supplies a single platform file with everything else — scheduled, queue, email, and tail handlers, plus named exports such as Durable Object classes, WorkerEntrypoint classes, and WorkflowEntrypoint classes.

Installation

Install the adapter:

npm install -D @joshthomas/sveltekit-adapter-cloudflare

Usage

Configure SvelteKit to use the adapter:

import adapter from '@joshthomas/sveltekit-adapter-cloudflare';

export default {
    kit: {
        adapter: adapter()
    }
};

Then create src/platform.cloudflare.js (or .ts) and export any Cloudflare-specific additions you need:

import { DurableObject } from 'cloudflare:workers';

export class MyDurableObject extends DurableObject {}

export async function scheduled(controller, env, ctx) {
    // run cron work here
}

export async function queue(batch, env, ctx) {
    for (const message of batch.messages) {
        // process message.body here
        message.ack();
    }
}

export async function email(message, env, ctx) {
    // handle incoming email here
}

The adapter re-exports everything from this file and merges any scheduled, queue, email, or tail exports into the generated worker's default export. It does not replace SvelteKit's fetch handler.

See the Cloudflare docs for handler signatures — scheduled, queue, email, tail — and for class-based exports: Durable Objects, WorkerEntrypoint, and Workflows.

The adapter discovers platform files automatically by looking for platform.cloudflare.<ext> in kit.files.src using kit.moduleExtensions. If you want to use a different file, pass it explicitly:

adapter({
    platform: 'src/workers/my-platform.js'
});

These exports are wired in the adapter output, so they are not available in plain vite dev. To test them locally, use your normal Cloudflare preview flow — for example wrangler pages dev for Pages or vite build followed by wrangler dev for Workers.

For the rest of the adapter behavior and options, see the upstream docs.

Development

To work on the adapter locally:

pnpm install
pnpm build
pnpm check
pnpm test:unit
pnpm test:e2e

License

sveltekit-adapter-cloudflare is licensed under the MIT license. See the LICENSE file for more information.