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Deploy a Svelte site

Svelte is an increasingly popular, open-source framework for building user interfaces and web applications. Unlike most frameworks, Svelte is primarily a compiler that converts your component code into efficient JavaScript that surgically updates the DOM when your application state changes.

In this guide, you will create a new Svelte application and deploy it using Cloudflare Pages. You will use SvelteKit, the official Svelte framework for building web applications of all sizes.

​​ Setting up a new project

Create a new project by running the npm init command in your terminal, giving it a title:

$ npm init [email protected] my-svelte-app
$ cd my-svelte-app

During init, SvelteKit will prompt you for customization choices. Your answers will not affect the rest of this tutorial. Choose the option that is ideal for your project.

​​ Before you continue

All of the framework guides assume you already have a fundamental understanding of Git. If you are new to Git, refer to this summarized Git handbook on how to set up Git on your local machine.

If you clone with SSH, you must generate SSH keys on each computer you use to push or pull from GitHub.

Refer to the GitHub documentation and Git documentation for more information.

​​ Creating a GitHub repository

Create a new GitHub repository by visiting repo.new. After creating a new repository, prepare and push your local application to GitHub by running the following commands in your terminal:

# Setup the local repository
$ git init
$ git remote add origin https://github.com/<username>/<repo>
$ git branch -M main
# Commit all initial files
$ git add -A
$ git commit -m "initial commit"
# Send commit to new GitHub repo
$ git push -u origin main

​​ Deploying with Cloudflare Pages

Deploy your site to Pages by logging in to the Cloudflare dashboard > Account Home > Pages and selecting Create a project.

You will be asked to authorize access to your GitHub account if you have not already done so. Cloudflare needs this so that it can monitor and deploy your projects from the source. You may narrow access to specific repositories if you prefer; however, you will have to manually update this list within your GitHub settings when you want to add more repositories to Cloudflare Pages.

Select the new GitHub repository that you created and, in the Set up builds and deployments section, provide the following information:

Configuration optionValue
Production branchmain
Build commandnpm run build
Build directorybuild
Environment VariablesNODE_VERSION: 17

Optionally, you can customize the Project name field. It defaults to the GitHub repository’s name, but it does not need to match. The Project name value is assigned as your *.pages.dev subdomain.

​​ SvelteKit Configuration

Currently, SvekteKit has three available adapters that you can use to deploy a SvelteKit project to Cloudflare Pages.

  1. @sveltejs/adapter-auto
  2. @sveltejs/adapter-cloudflare
  3. @sveltejs/adapter-static

You will need to pick the one that best suits your use case.

​​ SvelteKit Adapter Auto

The SvelteKit project’s default configuration uses @sveltejs/adapter-auto, which automatically chooses the adapter for your current environment. While you can use this default adapter when deploying to Cloudflare Pages by setting your Build directory to .svelte-kit/cloudflare, local development has a few disadvantages.

When building locally, @sveltejs/adapter-auto has no way to know what platform you are going to deploy to. This will cause the build to fail. Since the environment variables are not set, you cannot use Cloudflare Pages features, like Direct Uploads or Functions, locally.

To deploy your Sveltekit application in production, update the Build directory to .svelte-kit/cloudflare. This lets the @sveltejs/adapter-auto package know you are deploying to a Cloudflare Pages environment.

​​ SvelteKit Cloudflare

@sveltejs/adapter-cloudflare supports all SvelteKit features and builds for Cloudflare Pages. The Cloudflare adapter is recommended because it supports expected local development and production behaviours.

​​ Usage

To add the SvelteKit Cloudflare adapter to your application:

  1. Install the Cloudflare Adapter by running npm i --save-dev @sveltejs/adapter-cloudflare in your terminal.
  2. Include the adapter in svelte.config.js:

svelte.config.js
++ import adapter from '@sveltejs/adapter-cloudflare';
++
/** @type {import('@sveltejs/kit').Config} */
const config = {
kit: {
++ adapter: adapter(),
// ... truncated ...
}
};
export default config;
3. Include support for environment variables. The env object, containing KV namespaces and other storage objects, is passed to SvelteKit via the platform property along with context and caches, meaning you can access it in hooks and endpoints. For example:

src/app.d.ts
declare namespace App {
interface Locals {}
+ interface Platform {
+ env: {
+ COUNTER: DurableObjectNamespace;
+ };
+ context: {
+ waitUntil(promise: Promise<any>): void;
+ };
+ caches: CacheStorage & { default: Cache }
+ }
interface Session {}
interface Stuff {}
}
4. Access the added KV or Durable objects namespace in your endpoint with env :
export async function post({ request, platform }) {
const counter = platform.env.COUNTER.idFromName('A');
}

When deploying with @sveltejs/adapter-cloudflare or @sveltejs/adapter-auto, select the new GitHub repository that you created and, in Set up builds and deployments of your Pages project setup, provide the following information:

Configuration optionValue
Production branchmain
Build commandnpm run build
Build directory.svelte-kit/cloudflare
Environment VariablesNODE_VERSION: 17

​​ SvelteKit Static adapter

The static adapter only produces client-side static assets (no server-side rendering) and is compatible with Cloudflare Pages. To use this adapter, install the @sveltejs/adapter-static package:

$ npm install @sveltejs/[email protected] --save-dev

Then, in the svelte.config.js file, update the adapter selection:

svelte.config.js
++ import adapter from '@sveltejs/adapter-static';
++
/** @type {import('@sveltejs/kit').Config} */
const config = {
kit: {
++ adapter: adapter(
++ {
++ // default options are shown. On some platforms
++ // these options are set automatically — see below
++ pages: 'build',
++ assets: 'build',
++ fallback: null,
++ precompress: false
++ }
++),
++ prerender: {
++ // This can be false if you're using a fallback (i.e. SPA mode)
++ default: true
++ }
}
};
export default config;

When deploying a SvelteKit application using @sveltejs/adapter-static set the Build directory to build.

​​ Finalize Setup

After completing configuration, click the Save and Deploy button.

You will see your first deploy pipeline in progress. Pages installs all dependencies and builds the project as specified.

Cloudflare Pages will automatically rebuild your project and deploy it on every new pushed commit.

Additionally, you will have access to preview deployments, which repeat the build-and-deploy process for pull requests. With these, you can preview changes to your project with a real URL before deploying them to production.

​​ Functions setup

In SvelteKit, functions are written as endpoints. Functions contained in the /functions directory at the project’s root will not be included in the deployment, which compiles to a single _worker.js file.

When writing your endpoints in SvelteKit, attach the corresponding onRequest handler to your SvelteKit endpoint. For example:

src/routes/random.js
/** @type {import('@sveltejs/kit').RequestHandler} */
export async function get() {
return {
status: 200,
headers: {
'access-control-allow-origin': '*'
},
body: {
number: Math.random()
}
};
}

The GET request handler here will correspond to an onRequestGet in Pages Functions.

​​ Functions error logging

Logs are not available as Pages Functions is currently in beta. A third-party alternative, such as Sentry, can be used for logging with Pages Functions.

By completing this guide, you have successfully deployed your Svelte site to Cloudflare Pages. To get started with other frameworks, refer to the list of Framework guides.