@eslym/sveltekit-adapter-bun

Another sveltekit adapter for bun, an alternative to svelte-adapter-bun. This package support websocket in dev mode with few steps of setup.

The built bundle with version 2.0.0 will be ready to compile into single executable with bun.

Installation

bun add -d @eslym/sveltekit-adapter-bun

Important

Breaking Changes

Since version 2.0.0, the custom hooks (beforeServe, afterServe and setupCLI) and CLI functionality is complemetely removed.

Setup dev server

Note

You do not need to do this if you are not using websocket in dev mode.

1. Create an entrypoint file for dev server, e.g. ./dev.ts

2. Add the following code to the entrypoint file

   import { patchSvelteKit, startDevServer } from '@eslym/sveltekit-adapter-bun';
   
   await patchSvelteKit();
   await startDevServer();

3. run bun dev.ts

The patchSvelteKit function will patch the sveltekit using bun patch to let it get the original Request object from bun and pass it to the dev server, making Bun.Server#upgrade possible. The startDevServer function will start the dev server with websocket support.

The patchSvelteKit will not impact anything in production build, since the production build will not involve @sveltejs/kit/node unless you are using it in your code.

Important

This dev server uses bun's internal stuff, so it might break in the future bun version, but the production build will not be affected.

Use the websocket

// ./src/app.d.ts
// for the type checking

import type { AdapterPlatform } from '@eslym/sveltekit-adapter-bun';

// See https://kit.svelte.dev/docs/types#app
// for information about these interfaces
declare global {
    namespace App {
        // interface Error {}
        // interface Locals {}
        // interface PageData {}
        // interface PageState {}
        interface Platform extends AdapterPlatform {}
    }
}

// ./src/routes/echo/+server.ts

export async function GET({ platform }) {
    // can mark any response for upgrade, if the upgrade failed, the response will be sent as is
    return platform!.markForUpgrade(
        new Response('Websocket Requried', {
            status: 400
        }),
        {
            message(ws, message) {
                ws.send(message);
            }
        }
    );
}

Adapter Options

export type AdapterOptions = {
    /**
     * Output path
     * @default './build'
     */
    out?: string;

    /**
     * The bundler for the final step build.
     * @default 'rollup'
     */
    bundler?: 'rollup' | 'bun';

    /**
     * Enable pre-compress, use number to specify a minimum file size which will be compressed.
     * When it is true, the minimum size is 1KiB.
     *
     * @default false
     */
    precompress?: boolean | PreCompressOptions | number;

    /**
     * Serve static assets, set if to false if you want to handle static assets yourself
     * like using nginx or caddy. When it is true, an index of assets will build with
     * bun's `import with { type: 'file' }` syntax, which make it ready to bundle into
     * single executable file.
     *
     * @default true
     */
    serveStatic?: boolean;

    /**
     * File patterns to be ignored in the static assets, ex: `*.{br,gz}`
     * @default ["**​/.*"]
     */
    staticIgnores?: string[];

    /**
     * Export prerendered entries as json
     * @default false
     */
    exportPrerender?: boolean;

    /**
     * Include source maps
     *
     * @default true
     */
    sourceMap?: boolean | 'inline';

    /**
     * Minify the output when using bun build
     *
     * @default false
     */
    bunBuildMinify?:
        | boolean
        | {
              whitespace?: boolean;
              syntax?: boolean;
              identifiers?: boolean;
          };
};

export type PreCompressOptions = {
    /**
     * Enable specific compression, number means the minimum size to compress.
     * 1KiB will be used when the value is `true`, set to `0` for always compress.
     *
     * @default true;
     */
    [k in 'gzip' | 'brotli']?: boolean | number;
} & {
    /**
     * Extensions to pre-compress
     * @default ['html','js','json','css','svg','xml','wasm']
     */
    files?: string[];
};

Runtime Environments

Name	Description	Default
HTTP_HOST	The host for the server	0.0.0.0
HTTP_PORT	The port for the server	3000
HTTP_SOCKET	The path of the unix socket which the server will listen to (this will disable http)	-
HTTP_PROTOCOL_HEADER	The header name to get the protocol from the request	-
HTTP_HOST_HEADER	The header name to get the host from the request	-
HTTP_IP_HEADER	The header name to get the client ip from the request (usually X-Forwarded-For)	-
HTTP_XFF_DEPTH	The depth of the X-Forwarded-For header to get the client ip	1
HTTP_OVERRIDE_ORIGIN	Force the request origin when it is unable to retrieve from the request	-
HTTP_IDLE_TIMEOUT	The request timeout for the server(in seconds)	30
HTTP_MAX_BODY	The maximum body size for the request	128mib
WS_IDLE_TIMEOUT	The websocket idle timeout (in seconds)	120
WS_MAX_PAYLOAD	The maximum payload size for the websocket	16mib
WS_NO_PING	Disable automatic ping response	false
CACHE_ASSET_AGE	The max-age for the cache-control header for the assets	14400
CACHE_IMMUTABLE_AGE	The max-age for the cache-control header for the immutable assets	31536000