Add ability to add custom include & exclude patterns. Blacklist static assets for middleware

Author: psd-coder

astro.config.mjs

@@ -210,7 +210,9 @@ export default defineConfig({
       supportedLanguages: SUPPORTED_LANGUAGES,
       manualMatchers: ["/en", "/en/:path*"],
     }),
-    vercelMiddlewareIntegration(),
+    vercelMiddlewareIntegration({
+      exclude: ["/(.*).(png|jpg|jpeg|gif|svg|webp|avif|ico|css|js|map|ico)"],
+    }),
   ],
   adapter: process.env.VERCEL
     ? vercel({

integrations/vercel-middleware/index.ts

@@ -1,7 +1,7 @@
 import { fileURLToPath } from "node:url";
 import type { AstroConfig, AstroIntegration, IntegrationResolvedRoute } from "astro";
 import { getAstroMiddlewarePath } from "./utils/astro";
-import { buildMiddlewareMatcherRegexp } from "./utils/matcher";
+import { buildMiddlewareMatcherRegexp, type MatcherOptions } from "./utils/matcher";
 import { generateEdgeMiddlewareFile } from "./utils/middleware";
 import {
   generateFunctionConfig,
@@ -13,7 +13,9 @@ const INTEGRATION_NAME = "vercel-middleware";
 const VERCEL_ADAPTER_LINK = "[@astrojs/vercel](https://www.npmjs.com/package/@astrojs/vercel)";
 const VERCEL_MIDDLEWARE_FUNCTION_NAME = "_middleware";
 
-export default function vercelMiddlewareIntegration() {
+type VercelMiddlewareIntegrationOptions = MatcherOptions;
+
+export default function vercelMiddlewareIntegration(options?: VercelMiddlewareIntegrationOptions) {
   let astroConfig: AstroConfig;
   let resolvedRoutes: IntegrationResolvedRoute[];
 
@@ -68,6 +70,7 @@ export default function vercelMiddlewareIntegration() {
         const matcher = buildMiddlewareMatcherRegexp({
           assetsDir: astroConfig.build.assets,
           routes: resolvedRoutes,
+          ...options,
         });
 
         logger.info("Inserting generated middleware into vercel output config…");

integrations/vercel-middleware/utils/matcher.ts

@@ -1,31 +1,45 @@
 import type { IntegrationResolvedRoute } from "astro";
 
-interface BuildMiddlewareMatcherRegexpOptions {
+export interface MatcherOptions {
+  include?: (string | RegExp)[];
+  exclude?: (string | RegExp)[];
+}
+
+interface BuildMiddlewareMatcherRegexpOptions extends MatcherOptions {
   assetsDir: string;
   routes: IntegrationResolvedRoute[];
 }
 
 export function buildMiddlewareMatcherRegexp({
   routes,
   assetsDir,
+  exclude,
+  include,
 }: BuildMiddlewareMatcherRegexpOptions) {
-  const assetsPattern = `/${assetsDir}/(.*)`;
   const groupedRoutes = Object.groupBy(routes, (r) => r.origin);
-  const internalPatterns =
-    groupedRoutes.internal?.map((r) => stripPatternRegexp(r.patternRegex)) ?? [];
+  const dontMatchPatterns = [
+    `/${assetsDir}/(.*)`,
+    ...(groupedRoutes.internal?.map((r) => stripAstroRoutePatternRegexp(r.patternRegex)) ?? []),
+    ...(exclude ?? []).map(stripRoutePattern),
+  ];
+  const matchPatterns = [...(include ?? []).map(stripRoutePattern)];
 
-  // The regex is constructed to negate any internal Astro paths
-  // For example it can output such regexp: /^(?!.*\/(_server-islands\/[^\/]+\/?|_image\/?)$).*$/;
-  return `^(?!.*(${[assetsPattern, ...internalPatterns].join("|")})$).*$`;
+  // The regex is constructed to first negate any paths that match the internal patterns
+  // and then allow paths that match the project patterns.
+  // For example it can output such regexp: /^(?!.*\/(_server-islands\/[^\/]+\/?|_image\/?)$)(?:\/(.*?))?\/?)$/;
+  return `^(?!.*(${dontMatchPatterns.join("|")})$)(?:${matchPatterns.join("|")})$`;
 }
 
 // Strips leading ^ and trailing $ from a RegExp pattern string
 const PATTERN_STRIP_LINE_START = /^\^/;
 const PATTERN_STRIP_LINE_END = /\$$/;
-function stripPatternRegexp(pattern: RegExp) {
+function stripRoutePattern(pattern: string | RegExp) {
   return pattern
     .toString()
-    .slice(1, -1)
     .replace(PATTERN_STRIP_LINE_START, "")
     .replace(PATTERN_STRIP_LINE_END, "");
 }
+
+function stripAstroRoutePatternRegexp(pattern: RegExp) {
+  return stripRoutePattern(pattern.toString().slice(1, -1));
+}