svelte-adapter-fastly

A SvelteKit adapter that deploys to fastly compute services

See the docs for fastly-compute

Getting Started

Prerequisites

You will need all the fastly edgeworker CLI tools installed. These should get installed automatically with the package but if not you can install them manually.

pnpm i @fastly/js-compute @fastly/compute-js-static-publish

1. Set the Adapter in your svelte.config.js

import adapter from "svelte-adapter-fastly";
import { vitePreprocess } from "@sveltejs/vite-plugin-svelte";

/** @type {import('@sveltejs/kit').Config} */
const config = {
  preprocess: vitePreprocess(),
  kit: {
    adapter: adapter(),
  },
};

2. You will need a valid fastly.toml at the the base of your Sveltekit project.

   • Make sure it has a script to run pnpm build.

3. You can test your project via the fastly CLI using fastly compute serve

Options

silent

By default if a fastly.toml file is not included this adapter will help you make one. You can avoid this option in CI/CD enviroments by passing silent: true

staticPublishConfig

Due to its nature as an edgeworker Fastly needs to compile static assets to be served by the edgeworker. This adapter uses compute-js-static-publish to handle this, and uses a default config that should work well for most use cases. However, if you would like to customize this using a static-publish.rc.js you can supply the path to it here. This would be useful if you want to store your assets in a KV store instead of binary.

entry

You can supply a custom entry file if you want to add middleware before SvelteKit is called, or just want greater customization of the edgeworker.

You can do this by importing handleSvelteKitRequest into your entry file.

//entry.js 
import { handleSvelteKitRequest } from "svelte-adapter-fastly"

/// <reference types="@fastly/js-compute" />
addEventListener("fetch", event => event.respondWith(handleRequest(event)));

/**
 * @param {FetchEvent} event
 */
async function handleRequest(event) {
    // Get the request from the client.
    const req = event.request;

    const headers = new Headers();
    headers.set('Content-Type', 'text/plain');

    //Requests with edge in URL will return plain non sveltekit response
    if (req.url.includes("edge")) {
        return new Response("Hi from the edge", {
            status: 200,
            headers
        })
    }
    else {
        //everyone else gets the kit!
        return handleSvelteKitRequest(event);
    }
}