Add CloudFront Function for directory index routing

- Create CloudFront Function to rewrite directory requests to index.html
- Fix admin login page routing issue (/upadaj -> /upadaj/index.html)
- Attach function to CloudFront distribution default cache behavior
- Enables proper routing for all admin pages without .html extension

terraform/cloudfront-frontend.tf

@@ -40,6 +40,15 @@ resource "aws_cloudfront_origin_access_control" "frontend" {
   signing_protocol                  = "sigv4"
 }
 
+# CloudFront Function for directory index rewrites
+resource "aws_cloudfront_function" "index_rewrite" {
+  name    = "${var.app_name}-index-rewrite"
+  runtime = "cloudfront-js-1.0"
+  comment = "Rewrite directory requests to index.html"
+  publish = true
+  code    = file("${path.module}/cloudfront-function.js")
+}
+
 # CloudFront distribution
 resource "aws_cloudfront_distribution" "frontend" {
   enabled             = true
@@ -74,6 +83,11 @@ resource "aws_cloudfront_distribution" "frontend" {
     default_ttl            = 3600   # 1 hour
     max_ttl                = 86400  # 24 hours
     compress               = true
+
+    function_association {
+      event_type   = "viewer-request"
+      function_arn = aws_cloudfront_function.index_rewrite.arn
+    }
   }
 
   # Custom error responses for SPA routing

terraform/cloudfront-function.js

@@ -0,0 +1,17 @@
+function handler(event) {
+    var request = event.request;
+    var uri = request.uri;
+
+    // Check whether the URI is missing a file extension
+    if (!uri.includes('.')) {
+        // Check if URI ends with /
+        if (uri.endsWith('/')) {
+            request.uri += 'index.html';
+        } else {
+            // Add /index.html to directory paths
+            request.uri += '/index.html';
+        }
+    }
+
+    return request;
+}