@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

[!CAUTION] This dev server is no longer work since bun v1.2.6, see https://github.com/eslym/sveltekit-adapter-bun/issues/3, but the production server will still function as expected.

[!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;
          };

    /**
     * Expose the Bun version to the client via public env (`PUBLIC_BUN_VERSION`).
     * @default false
     */
    exposeBunVersionToClient?: boolean;

    /**
     * Expose the Bun revision to the client via public env (`PUBLIC_BUN_REVISION`).
     * @default false
     */
    exposeBunRevisionToClient?: 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_TRUSTED_PROXIES | A comma separated list of trusted proxies IP or CIDR, used to determine the client IP and override origin | - | | 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 | | TLS_CERT_FILE | Path to the TLS certificate file (PEM). Enables HTTPS when set alongside TLS_KEY_FILE | - | | TLS_KEY_FILE | Path to the TLS private key file (PEM). Required with TLS_CERT_FILE to enable HTTPS | - | | TLS_CA_FILE | Optional path to a CA bundle file (PEM) | - | | TLS_PASSPHRASE | Optional passphrase for an encrypted TLS_KEY_FILE | - | | 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 |