default.fetch() — astro Function Reference

Architecture documentation for the default.fetch() function in entrypoint.ts from the astro codebase.

Function typescript CoreAstro CoreMiddleware

Entity Profile

CoreAstro→ CoreMiddleware→ default.fetch() — astro Function Reference

Dependency Diagram

graph TD
  ca769a02_99a1_c3c3_5e70_7a41d18bfb2c["default.fetch()"]
  888c71eb_1227_93b2_edd4_456430022b2c["entrypoint.ts"]
  ca769a02_99a1_c3c3_5e70_7a41d18bfb2c -->|defined in| 888c71eb_1227_93b2_edd4_456430022b2c
  style ca769a02_99a1_c3c3_5e70_7a41d18bfb2c fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/integrations/vercel/src/serverless/entrypoint.ts lines 16–62

	async fetch(request: Request): Promise<Response> {
		const url = new URL(request.url);
		const realPath =
			request.headers.get(ASTRO_PATH_HEADER) ?? url.searchParams.get(ASTRO_PATH_PARAM);
		if (typeof realPath === 'string') {
			url.pathname = realPath;
			request = new Request(url.toString(), {
				method: request.method,
				headers: request.headers,
				body: request.body,
			});
		}

		const routeData = app.match(request);

		let locals: Record<string, unknown> = {};

		const astroLocalsHeader = request.headers.get(ASTRO_LOCALS_HEADER);
		const middlewareSecretHeader = request.headers.get(ASTRO_MIDDLEWARE_SECRET_HEADER);
		if (astroLocalsHeader) {
			if (middlewareSecretHeader !== middlewareSecret) {
				return new Response('Forbidden', { status: 403 });
			}
			// hide the secret from the rest of user code
			request.headers.delete(ASTRO_MIDDLEWARE_SECRET_HEADER);
			locals = JSON.parse(astroLocalsHeader);
		}

		// https://vercel.com/docs/deployments/skew-protection#supported-frameworks
		if (skewProtection && process.env.VERCEL_SKEW_PROTECTION_ENABLED === '1') {
			request.headers.set('x-deployment-id', process.env.VERCEL_DEPLOYMENT_ID!);
		}

		const response = await app.render(request, {
			routeData,
			clientAddress: request.headers.get('x-forwarded-for') ?? undefined,
			locals,
		});

		if (app.setCookieHeaders) {
			for (const setCookieHeader of app.setCookieHeaders(response)) {
				response.headers.append('Set-Cookie', setCookieHeader);
			}
		}

		return response;
	},