createPreviewServer() — astro Function Reference

Architecture documentation for the createPreviewServer() function in preview.ts from the astro codebase.

Function typescript CoreAstro RoutingSystem

Entity Profile

CoreAstro→ RoutingSystem→ createPreviewServer() — astro Function Reference

Dependency Diagram

graph TD
  6008a2dc_9446_e8c8_ad66_7ad3826f0ef2["createPreviewServer()"]
  34969da5_3aef_c4dc_e500_3adc3dde5df6["preview.ts"]
  6008a2dc_9446_e8c8_ad66_7ad3826f0ef2 -->|defined in| 34969da5_3aef_c4dc_e500_3adc3dde5df6
  style 6008a2dc_9446_e8c8_ad66_7ad3826f0ef2 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/integrations/node/src/preview.ts lines 11–66

const createPreviewServer: CreatePreviewServer = async (preview) => {
	let ssrHandler: ServerModule['handler'];
	try {
		process.env.ASTRO_NODE_AUTOSTART = 'disabled';
		const ssrModule: MaybeServerModule = await import(preview.serverEntrypoint.toString());
		if (typeof ssrModule.handler === 'function') {
			ssrHandler = ssrModule.handler;
		} else {
			throw new AstroError(
				`The server entrypoint doesn't have a handler. Are you sure this is the right file?`,
			);
		}
	} catch (err) {
		if (
			(err as any).code === 'ERR_MODULE_NOT_FOUND' &&
			(err as any).url === preview.serverEntrypoint.href
		) {
			throw new AstroError(
				`The server entrypoint ${fileURLToPath(
					preview.serverEntrypoint,
				)} does not exist. Have you ran a build yet?`,
			);
		} else {
			throw err;
		}
	}
	// If the user didn't specify a host, it will already have been defaulted to
	// "localhost" by getResolvedHostForHttpServer in astro core/preview/util.ts.
	// The value `undefined` actually means that either the user set `options.server.host`
	// to `true`, or they passed `--host` without an argument. In that case, we
	// should listen on all IPs.
	const host = process.env.HOST ?? preview.host ?? '0.0.0.0';

	const port = preview.port ?? 4321;
	const server = createServer(ssrHandler, host, port);

	// If user specified custom headers append a listener
	// to the server to add those headers to response
	if (preview.headers) {
		server.server.addListener('request', (_, res) => {
			if (res.statusCode === 200) {
				for (const [name, value] of Object.entries(preview.headers ?? {})) {
					if (value) res.setHeader(name, value);
				}
			}
		});
	}

	logListeningOn(preview.logger, server.server, host);
	await new Promise<void>((resolve, reject) => {
		server.server.once('listening', resolve);
		server.server.once('error', reject);
		server.server.listen(port, host);
	});
	return server;
};