Build and deploy
Writing adapters
Edit this page on GitHubIf an adapter for your preferred environment doesn't yet exist, you can build your own. We recommend looking at the source for an adapter to a platform similar to yours and copying it as a starting point.
Adapter packages implement the following API, which creates an Adapter
:
ts
/** @param {AdapterSpecificOptions} options */export default function (options ) {/** @type {import('@sveltejs/kit').Adapter} */constadapter = {name : 'adapter-package-name',asyncadapt (builder ) {// adapter implementation},asyncemulate () {return {asyncType '({ config, route }: { config: any; route: { id: string; }; }) => void' is not assignable to type '(details: { config: any; route: { id: string; }; }) => boolean'. Type 'void' is not assignable to type 'boolean'.2322Type '({ config, route }: { config: any; route: { id: string; }; }) => void' is not assignable to type '(details: { config: any; route: { id: string; }; }) => boolean'. Type 'void' is not assignable to type 'boolean'.platform ({config ,prerender }) {// the returned object becomes `event.platform` during dev, build and// preview. Its shape is that of `App.Platform`}}},supports : {read : ({config ,route }) => {// Return `true` if the route with the given `config` can use `read`// from `$app/server` in production, return `false` if it can't.// Or throw a descriptive error describing how to configure the deployment}}};returnadapter ;}
Of these, name
and adapt
are required. emulate
and supports
are optional.
Within the adapt
method, there are a number of things that an adapter should do:
- Clear out the build directory
- Write SvelteKit output with
builder.writeClient
,builder.writeServer
, andbuilder.writePrerendered
- Output code that:
- Imports
Server
from${builder.getServerDirectory()}/index.js
- Instantiates the app with a manifest generated with
builder.generateManifest({ relativePath })
- Listens for requests from the platform, converts them to a standard Request if necessary, calls the
server.respond(request, { getClientAddress })
function to generate a Response and responds with it - expose any platform-specific information to SvelteKit via the
platform
option passed toserver.respond
- Globally shims
fetch
to work on the target platform, if necessary. SvelteKit provides a@sveltejs/kit/node/polyfills
helper for platforms that can useundici
- Imports
- Bundle the output to avoid needing to install dependencies on the target platform, if necessary
- Put the user's static files and the generated JS/CSS in the correct location for the target platform
Where possible, we recommend putting the adapter output under the build/
directory with any intermediate output placed under .svelte-kit/[adapter-name]
.
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