Add example files

Author: joshAtRula

examples/complete/ab-testing.js

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+function handler(event) {
+  // A/B testing function using CloudFront Functions
+  // Assigns users to test groups and routes to different origin paths
+
+  var request = event.request;
+  var headers = request.headers;
+  var cookies = request.cookies;
+
+  // Check if user already has an A/B test cookie
+  var abTestGroup = null;
+
+  if (cookies['ab-test-group']) {
+    abTestGroup = cookies['ab-test-group'].value;
+  } else {
+    // Assign new users to a test group (50/50 split)
+    // Use CloudFront viewer ID for consistent assignment
+    var viewerId = event.viewer.address;
+    var hash = 0;
+
+    for (var i = 0; i < viewerId.length; i++) {
+      hash = ((hash << 5) - hash) + viewerId.charCodeAt(i);
+      hash = hash & hash; // Convert to 32bit integer
+    }
+
+    abTestGroup = (Math.abs(hash) % 2 === 0) ? 'A' : 'B';
+
+    // Note: CloudFront Functions cannot set cookies
+    // You would set this cookie in the response (using viewer-response function)
+    // or via JavaScript on the client side
+  }
+
+  // Route to different paths based on test group
+  var uri = request.uri;
+
+  if (abTestGroup === 'B' && !uri.startsWith('/variant-b/')) {
+    // Rewrite path for variant B users
+    request.uri = '/variant-b' + uri;
+  }
+
+  // Add header for origin to know which variant was served
+  headers['x-ab-test-group'] = {
+    value: abTestGroup
+  };
+
+  return request;
+}

examples/complete/kvstore-redirect.js

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+function handler(event) {
+  // CloudFront Function with KeyValueStore integration
+  // Uses KV store for dynamic URL redirects and feature flags
+
+  var request = event.request;
+  var uri = request.uri;
+
+  // Note: To use KeyValueStore, associate the KV store ARN with this function
+  // Example: key_value_store_associations = ["arn:aws:cloudfront::123456789012:key-value-store/redirects"]
+
+  // Uncomment when KV store is associated:
+  /*
+  var kvsHandle = event.context.kvs;
+
+  // Look up redirect mapping in KeyValueStore
+  var redirectTarget = kvsHandle.get(uri);
+
+  if (redirectTarget) {
+    // Redirect to target URL from KV store
+    var response = {
+      statusCode: 301,
+      statusDescription: 'Moved Permanently',
+      headers: {
+        'location': { value: redirectTarget },
+        'cache-control': { value: 'max-age=3600' }
+      }
+    };
+    return response;
+  }
+
+  // Check feature flags in KV store
+  var featureFlags = kvsHandle.get('feature-flags');
+  if (featureFlags) {
+    var flags = JSON.parse(featureFlags);
+
+    // Add feature flag headers for origin
+    if (flags.enableNewUI) {
+      request.headers['x-feature-new-ui'] = { value: 'true' };
+    }
+  }
+  */
+
+  // For now, return request as-is
+  // When KV store is configured, uncomment the code above
+  return request;
+}

examples/complete/viewer-request-security.js

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+function handler(event) {
+  // Viewer request function to add security headers and normalize cache keys
+  // This function runs before CloudFront checks the cache
+
+  var request = event.request;
+  var headers = request.headers;
+
+  // Normalize Host header for consistent caching
+  if (headers.host) {
+    headers.host.value = headers.host.value.toLowerCase();
+  }
+
+  // Remove query parameters that don't affect content (for better cache hit ratio)
+  var uri = request.uri;
+  var querystring = request.querystring;
+
+  // Example: Remove tracking parameters but keep content-affecting ones
+  var allowedParams = ['id', 'page', 'category'];
+  var newQuerystring = {};
+
+  for (var param in querystring) {
+    if (allowedParams.includes(param)) {
+      newQuerystring[param] = querystring[param];
+    }
+  }
+
+  request.querystring = newQuerystring;
+
+  // Add custom header for logging/debugging
+  headers['x-viewer-country'] = {
+    value: event.viewer.country || 'unknown'
+  };
+
+  return request;
+}

examples/complete/viewer-response-headers.js

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+function handler(event) {
+  // Viewer response function to add security and performance headers
+  // This function runs after CloudFront receives the response from origin
+
+  var response = event.response;
+  var headers = response.headers;
+
+  // Add security headers
+  headers['strict-transport-security'] = {
+    value: 'max-age=63072000; includeSubdomains; preload'
+  };
+
+  headers['x-content-type-options'] = {
+    value: 'nosniff'
+  };
+
+  headers['x-frame-options'] = {
+    value: 'DENY'
+  };
+
+  headers['x-xss-protection'] = {
+    value: '1; mode=block'
+  };
+
+  headers['referrer-policy'] = {
+    value: 'strict-origin-when-cross-origin'
+  };
+
+  // Add cache control for static assets
+  if (event.request.uri.match(/\.(jpg|jpeg|png|gif|ico|css|js|woff|woff2)$/)) {
+    headers['cache-control'] = {
+      value: 'public, max-age=31536000, immutable'
+    };
+  }
+
+  // Add custom header to identify CloudFront Functions processing
+  headers['x-cloudfront-function'] = {
+    value: 'viewer-response-headers'
+  };
+
+  return response;
+}