remember to use a custom header for all cache-related headers

probcomp · Nov 7, 2024 · a474d88 · a474d88
1 parent 4915133
commit a474d88
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Showing 2 changed files with 69 additions and 45 deletions.
diff --git a/private-website-cache/src/worker.js b/private-website-cache/src/worker.js
@@ -1,38 +1,56 @@
 export default {
   async fetch(request, env, ctx) {
-    // Add ETag and If-Modified-Since handling
-    const ifNoneMatch = request.headers.get('If-None-Match');
-    const ifModifiedSince = request.headers.get('If-Modified-Since');
     const response = await fetch(request);
 
-    // Check both ETag and Last-Modified
-    if ((ifNoneMatch && response.headers.get('ETag') === ifNoneMatch) ||
-        (ifModifiedSince && response.headers.get('Last-Modified') === ifModifiedSince)) {
-      return new Response(null, {
-        status: 304,
-        headers: new Headers({
-          'Cache-Control': response.headers.get('Cache-Control'),
-          'ETag': response.headers.get('ETag'),
-          'Last-Modified': response.headers.get('Last-Modified')
-        })
-      });
-    }
-
-    // Check for custom cache policy
-    const cachePolicyHeader = response.headers.get('X-Cache-Policy');
-    if (cachePolicyHeader) {
+    // Check for custom cache info
+    const cacheInfoHeader = response.headers.get('X-Cache-Info');
+    if (cacheInfoHeader) {
       try {
-        const policy = JSON.parse(cachePolicyHeader);
+        const cacheInfo = JSON.parse(cacheInfoHeader);
         const modifiedResponse = new Response(response.body, response);
+
+        // Clear any existing cache headers that might have been set by IAP
         modifiedResponse.headers.delete('Pragma');
         modifiedResponse.headers.delete('Cache-Control');
         modifiedResponse.headers.delete('Expires');
-        modifiedResponse.headers.set('Cache-Control', `${policy.visibility}, max-age=${policy.maxAge}`);
-        const expiresDate = new Date(Date.now() + policy.maxAge * 1000);
-        modifiedResponse.headers.set('Expires', expiresDate.toUTCString());
+        modifiedResponse.headers.delete('ETag');
+        modifiedResponse.headers.delete('Last-Modified');
+
+        // Restore cache control headers
+        const { policy, expires, etag, lastModified } = cacheInfo;
+        modifiedResponse.headers.set(
+          'Cache-Control',
+          `${policy.visibility}, max-age=${policy.maxAge}, stale-while-revalidate=${policy.staleWhileRevalidate}`
+        );
+        modifiedResponse.headers.set('Expires', expires);
+
+        // Restore validation headers
+        if (etag) {
+          modifiedResponse.headers.set('ETag', etag);
+        }
+        if (lastModified) {
+          modifiedResponse.headers.set('Last-Modified', lastModified);
+        }
+
+        // Handle conditional requests
+        const ifNoneMatch = request.headers.get('If-None-Match');
+        const ifModifiedSince = request.headers.get('If-Modified-Since');
+
+        if ((ifNoneMatch && etag === ifNoneMatch) ||
+            (ifModifiedSince && lastModified === ifModifiedSince)) {
+          return new Response(null, {
+            status: 304,
+            headers: new Headers({
+              'Cache-Control': modifiedResponse.headers.get('Cache-Control'),
+              'ETag': etag,
+              'Last-Modified': lastModified
+            })
+          });
+        }
+
         return modifiedResponse;
       } catch (e) {
-        console.error('Failed to parse cache policy:', e);
+        console.error('Failed to parse cache info:', e);
       }
     }
 

diff --git a/src/server.mjs b/src/server.mjs
@@ -17,8 +17,6 @@ import * as assert from 'assert'
 
 const { BUCKET_NAME } = process.env;
 
-const HTML_MAX_AGE = 60;
-
 export const app = express();
 const storage = new Storage();
 const default_bucket = storage.bucket(BUCKET_NAME);
@@ -49,30 +47,43 @@ const handleResponseError = (res, error) => {
 }
 
 const CACHE_POLICIES = {
-    HTML: { maxAge: 60, visibility: 'private' },
-    STATIC: { maxAge: 600, visibility: 'public' },
-    SIGNED_URL: { maxAge: 3000, visibility: 'public' },
+    HTML: { maxAge: 60, visibility: 'private', staleWhileRevalidate: 30 },
+    STATIC: { maxAge: 86400, visibility: 'public', staleWhileRevalidate: 3600 }, // 24 hours for static assets
+    SIGNED_URL: { maxAge: 3000, visibility: 'public', staleWhileRevalidate: 300 },
 };
 
-const setCacheHeaders = (res, policy) => {
-    res.setHeader('X-Cache-Policy', JSON.stringify(policy));
-    res.setHeader('Cache-Control', `${policy.visibility}, max-age=${policy.maxAge}`);
-    res.setHeader('Expires', new Date(Date.now() + policy.maxAge * 1000).toUTCString());
+const setCacheHeaders = (res, policy, metadata = {}) => {
+    // Consolidate all cache-related information into a single custom header
+    const cacheInfo = {
+        policy,
+        expires: new Date(Date.now() + policy.maxAge * 1000).toUTCString(),
+        etag: metadata.etag,
+        lastModified: metadata.updated,
+        contentType: metadata.contentType,
+        contentLength: metadata.size
+    };
+
+    res.setHeader('X-Cache-Info', JSON.stringify(cacheInfo));
+
+    // Set standard headers anyway (for local development)
+    res.setHeader('Cache-Control', `${policy.visibility}, max-age=${policy.maxAge}, stale-while-revalidate=${policy.staleWhileRevalidate}`);
+    res.setHeader('Expires', cacheInfo.expires);
+    if (metadata.etag) {
+        res.setHeader('ETag', metadata.etag);
+    }
+    if (metadata.updated) {
+        res.setHeader('Last-Modified', metadata.updated);
+    }
 };
 
 const serveFile = async (res, path) => {
     try {
         const file = default_bucket.file(path);
         const [metadata] = await file.getMetadata();
 
-        setCacheHeaders(res, CACHE_POLICIES.STATIC);
+        setCacheHeaders(res, CACHE_POLICIES.STATIC, metadata);
         res.setHeader('Content-Type', metadata.contentType);
         res.setHeader('Content-Length', metadata.size);
-        res.setHeader('Last-Modified', metadata.updated);
-
-        if (metadata.etag) {
-            res.setHeader('ETag', metadata.etag);
-        }
 
         const stream = file.createReadStream();
         stream.on('error', (err) => handleResponseError(res, err));
@@ -87,13 +98,8 @@ const serveHtml = async (res, path) => {
         const htmlFile = default_bucket.file(path);
         const [metadata] = await htmlFile.getMetadata();
 
+        setCacheHeaders(res, CACHE_POLICIES.HTML, metadata);
         res.setHeader('Content-Type', 'text/html');
-        res.setHeader('Last-Modified', metadata.updated);
-        setCacheHeaders(res, CACHE_POLICIES.HTML);
-
-        if (metadata.etag) {
-            res.setHeader('ETag', metadata.etag);
-        }
 
         return new Promise((resolve, reject) => {
             let rejectLogged = (err) => {