Add documentation (#2148)

* Add documentation

* Tweaks

* Fixes

* Rearrange

* Update
This commit is contained in:
Colin McDonnell
2023-02-23 17:13:30 -08:00
committed by GitHub
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{% callout %}
**Note** — Bun provides an [almost complete](/docs/runtime/nodejs#node_http) implementation of the Node.js [`http`](https://nodejs.org/api/http.html) and [`https`](https://nodejs.org/api/https.html) modules. This page only documents Bun-native APIs.
{% /callout %}
## Start a server
`Bun.serve(options) => Server`
Start an HTTP server in Bun with `Bun.serve`.
```ts
Bun.serve({
fetch(req) {
return new Response(`Bun!`);
},
});
```
The `fetch` handler handles incoming requests. It receives a [`Request`](https://developer.mozilla.org/en-US/docs/Web/API/Request) object and returns a [`Response`](https://developer.mozilla.org/en-US/docs/Web/API/Response) or `Promise<Response>`.
```ts
Bun.serve({
fetch(req) {
const url = new URL(req.url);
if (url.pathname === "/") return new Response(`Home page!`);
if (url.pathname === "/blog") return new Response("Blog!");
return new Response(`404!`);
},
});
```
To configure which port and hostname the server will listen on:
```ts
Bun.serve({
port: 8080, // defaults to $PORT, then 3000
hostname: "mydomain.com", // defaults to "0.0.0.0"
fetch(req) {
return new Response(`404!`);
},
});
```
## Error handling
To activate development mode, set `development: true`. By default, development mode is _enabled_ unless `NODE_ENV` is `production`.
```ts
Bun.serve({
development: true,
fetch(req) {
throw new Error("woops!");
},
});
```
In development mode, Bun will surface errors in-browser with a built-in error page.
{% image src="/images/exception_page.png" caption="Bun's built-in 500 page" /%}
To handle server-side errors, implement an `error` handler. This function should return a `Response` to served to the client when an error occurs. This response will supercede Bun's default error page in `development` mode.
```ts
Bun.serve({
fetch(req) {
throw new Error("woops!");
},
error(error: Error) {
return new Response(`<pre>${error}\n${error.stack}</pre>`, {
headers: {
"Content-Type": "text/html",
},
});
},
});
```
{% callout %}
**Note** — Full debugger support is planned.
{% /callout %}
The call to `Bun.serve` returns a `Server` object. To stop the server, call the `.stop()` method.
```ts
const server = Bun.serve({
fetch() {
return new Response("Bun!");
},
});
server.stop();
```
## TLS
Bun supports TLS out of the box, powered by [OpenSSL](https://www.openssl.org/). Enable TLS by passing in a value for `keyFile` and `certFile`; both are required to enable TLS. If needed, supply a `passphrase` to decrypt the `keyFile`.
```ts
Bun.serve({
fetch(req) {
return new Response("Hello!!!");
},
keyFile: "./key.pem", // path to TLS key
certFile: "./cert.pem", // path to TLS cert
passphrase: "super-secret", // optional passphrase
});
```
The root CA and Diffie-Helman parameters can be configured as well.
```ts
Bun.serve({
fetch(req) {
return new Response("Hello!!!");
},
keyFile: "./key.pem", // path to TLS key
certFile: "./cert.pem", // path to TLS cert
caFile: "./ca.pem", // path to root CA certificate
dhParamsFile: "./dhparams.pem", // Diffie Helman parameters
});
```
## Hot reloading
Thus far, the examples on this page have used the explicit `Bun.serve` API. Bun also supports an alternate syntax.
```ts#server.ts
export default {
fetch(req) {
return new Response(`Bun!`);
},
};
```
Instead of passing the server options into `Bun.serve`, export it. This file can be executed as-is; when Bun runs a file with a `default` export containing a `fetch` handler, it passes it into `Bun.serve` under the hood.
This syntax has one major advantage: it is hot-reloadable out of the box. When any source file is changed, Bun will reload the server with the updated code _without restarting the process_. This makes hot reloads nearly instantaneous. Use the `--hot` flag when starting the server to enable hot reloading.
```bash
$ bun --hot server.ts
```
It's possible to configure hot reloading while using the explicit `Bun.serve` API; for details refer to [Runtime > Hot reloading](/docs/runtime/hot).
## Streaming files
To stream a file, return a `Response` object with a `BunFile` object as the body.
```ts
import { serve, file } from "bun";
serve({
fetch(req) {
return new Response(Bun.file("./hello.txt"));
},
});
```
{% callout %}
⚡️ **Speed** — Bun automatically uses the [`sendfile(2)`](https://man7.org/linux/man-pages/man2/sendfile.2.html) system call when possible, enabling zero-copy file transfers in the kernel—the fastest way to send files.
{% /callout %}
**[v0.3.0+]** You can send part of a file using the [`slice(start, end)`](https://developer.mozilla.org/en-US/docs/Web/API/Blob/slice) method on the `Bun.file` object. This automatically sets the `Content-Range` and `Content-Length` headers on the `Response` object.
```ts
Bun.serve({
fetch(req) {
// parse `Range` header
const [start = 0, end = Infinity] = req.headers
.get("Range") // Range: bytes=0-100
.split("=") // ["Range: bytes", "0-100"]
.at(-1) // "0-100"
.split("-") // ["0", "100"]
.map(Number); // [0, 100]
// return a slice of the file
const bigFile = Bun.file("./big-video.mp4");
return new Response(bigFile.slice(start, end));
},
});
```
## Benchmarks
Below are Bun and Node.js implementations of a simple HTTP server that responds `Bun!` to each incoming `Request`.
{% codetabs %}
```ts#Bun
Bun.serve({
fetch(req: Request) {
return new Response(`Bun!`);
},
port: 3000,
});
```
```ts#Node
require("http")
.createServer((req, res) => res.end("Bun!"))
.listen(8080);
```
{% /codetabs %}
The `Bun.serve` server can handle roughly 2.5x more requests per second than Node.js on Linux.
{% table %}
- Runtime
- Requests per second
---
- Node 16
- ~64,000
---
- Bun
- ~160,000
{% /table %}
{% image width="499" alt="image" src="https://user-images.githubusercontent.com/709451/162389032-fc302444-9d03-46be-ba87-c12bd8ce89a0.png" /%}
## Reference
{% details summary="See TypeScript definitions" %}
```ts
interface Bun {
serve(options: {
fetch: (req: Request, server: Server) => Response | Promise<Response>;
hostname?: string;
port?: number;
development?: boolean;
error?: (error: Error) => Response | Promise<Response>;
keyFile?: string;
certFile?: string;
caFile?: string;
dhParamsFile?: string;
passphrase?: string;
maxRequestBodySize?: number;
lowMemoryMode?: boolean;
}): Server;
}
interface Server {
development: boolean;
hostname: string;
port: number;
pendingRequests: number;
stop(): void;
}
```
{% /details %}