Merge pull request #2009 from brefphp/document-compression

Document HTTP responses compression

Author: mnapoli

docs/use-cases/websites.mdx

@@ -211,3 +211,40 @@ The last step will be to point your domain name DNS records to the CloudFront do
     - if you use another registrar and you want to point your root domain (without `www.`) to CloudFront, you will need to use a registrar that supports this (for example [CloudFlare allows this with a technique called CNAME flattening](https://support.cloudflare.com/hc/en-us/articles/200169056-Understand-and-configure-CNAME-Flattening))
 
 Lift supports more advanced use cases like multiple domains, root domain to `www` redirects, and more. Check out [the Lift documentation](https://github.com/getlift/lift/blob/master/docs/server-side-website.md).
+
+## Compressing HTTP responses
+
+By default, Lift enables gzip and brotli compression for static assets served from S3. That means that if a client supports compressed responses (via the `Accept-Encoding` header), [CloudFront will cache and serve a compressed version of the asset](https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/ServingCompressedFiles.html#compressed-content-cloudfront-how-it-works), which is usually smaller and faster to transfer.
+
+However, dynamic responses generated by PHP (for example HTML pages) are not compressed. The reason is that CloudFront's cache is disabled for requests to PHP (Lift sets up the [`CachingDisabled` policy](https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/using-managed-cache-policies.html#managed-cache-policy-caching-disabled)), and therefore CloudFront does not compress non-cached responses.
+
+You can compress PHP responses by using an HTTP middleware that compresses the response body and sets the `Content-Encoding` header. Here is an example for Laravel:
+
+```php filename="app/Http/Middleware/CompressResponse.php"
+class CompressResponse
+{
+    public function handle(Request $request, Closure $next)
+    {
+        /** @var \Illuminate\Http\JsonResponse $response */
+        $response = $next($request);
+
+        if (! in_array('gzip', $request->getEncodings())) {
+            return $response;
+        }
+        if ($response->headers->has('Content-Encoding')) {
+            return $response;
+        }
+
+        $content = $response->getContent();
+        if (! $content) {
+            return $response;
+        }
+
+        $response->setContent(gzencode($content, 9));
+        $response->headers->set('Content-Encoding', 'gzip');
+        $response->headers->set('Content-Length', (string) strlen($content));
+
+        return $response;
+    }
+}
+```