DO-1410: Lambda at edge handler lib

packages/lambda-at-edge-handlers/.gitignore

@@ -55,4 +55,4 @@ Thumbs.db
 cdk.out
 
 *.d.ts
-*.js
+*.js

packages/lambda-at-edge-handlers/index.ts

@@ -1,3 +1,13 @@
-import { prerenderHandler } from "./lib/prerender-handler";
+import { handler as PrerenderHandler } from "./lib/prerender";
+import { handler as PrerenderCacheControlHandler } from "./lib/cache-control";
+import { handler as PrerenderErrorResponseHandler } from "./lib/error-response";
+import { handler as PrerenderCheckHandler } from "./lib/prerender-check";
+import { handler as GeoIpRedirectHandler } from "./lib/redirect";
 
-export { prerenderHandler };
+export {
+  PrerenderHandler,
+  PrerenderCacheControlHandler,
+  PrerenderErrorResponseHandler,
+  PrerenderCheckHandler,
+  GeoIpRedirectHandler,
+};

packages/lambda-at-edge-handlers/lib/cache-control.ts

@@ -0,0 +1,21 @@
+import 'source-map-support/register';
+import { CloudFrontResponseEvent, CloudFrontResponse  } from 'aws-lambda';
+/*  
+    Prerender cache control function 
+    Consider associate this function as *origin response* function
+*/
+export const handler = async (event: CloudFrontResponseEvent): Promise<CloudFrontResponse> => {
+    const cacheKey = process.env.PRERENDER_CACHE_KEY || 'x-prerender-requestid';
+    const cacheMaxAge = process.env.PRERENDER_CACHE_MAX_AGE || '0';
+    let response = event.Records[0].cf.response;
+
+    if (response.headers[`${cacheKey}`]) {
+        response.headers['Cache-Control'] = [
+            {
+                key: 'Cache-Control',
+                value: `max-age=${cacheMaxAge}`
+            }
+        ]
+    }
+    return response;
+}

packages/lambda-at-edge-handlers/lib/error-response.ts

@@ -0,0 +1,61 @@
+import "source-map-support/register";
+import {
+  CloudFrontRequest,
+  CloudFrontResponseEvent,
+  CloudFrontResponse,
+} from "aws-lambda";
+import axios from "axios";
+import * as https from "https";
+
+const FRONTEND_HOST = process.env.FRONTEND_HOST;
+const PATH_PREFIX = process.env.PATH_PREFIX;
+
+// Create axios client outside of lambda function for re-use between calls
+const instance = axios.create({
+  timeout: 1000,
+  // Don't follow redirects
+  maxRedirects: 0,
+  // Only valid response codes are 200
+  validateStatus: function (status) {
+    return status == 200;
+  },
+  // keep connection alive so we don't constantly do SSL negotiation
+  httpsAgent: new https.Agent({ keepAlive: true }),
+});
+
+export const handler = (
+  event: CloudFrontResponseEvent
+): Promise<CloudFrontResponse | CloudFrontRequest> => {
+  let response = event.Records[0].cf.response;
+  let request = event.Records[0].cf.request;
+
+  if (
+    response.status != "200" &&
+    !request.headers["x-request-prerender"] &&
+    request.uri != `${PATH_PREFIX}/index.html`
+  ) {
+    // Fetch default page and return body
+    return instance
+      .get(`https://${FRONTEND_HOST}${PATH_PREFIX}/index.html`)
+      .then((res) => {
+        response.body = res.data;
+
+        response.headers["content-type"] = [
+          {
+            key: "Content-Type",
+            value: "text/html",
+          },
+        ];
+
+        // Remove content-length if set as this may be the value from the origin.
+        delete response.headers["content-length"];
+
+        return response;
+      })
+      .catch((err) => {
+        return response;
+      });
+  }
+
+  return Promise.resolve(response);
+};

packages/lambda-at-edge-handlers/lib/prerender-check.ts

@@ -0,0 +1,35 @@
+import "source-map-support/register";
+import { CloudFrontRequest, CloudFrontRequestEvent } from "aws-lambda";
+
+const IS_BOT =
+  /googlebot|chrome-lighthouse|lighthouse|adsbot\-google|Feedfetcher\-Google|bingbot|yandex|baiduspider|Facebot|facebookexternalhit|twitterbot|rogerbot|linkedinbot|embedly|quora link preview|showyoubot|outbrain|pinterest|slackbot|vkShare|W3C_Validator/i;
+const IS_FILE =
+  /\.(js|css|xml|less|png|jpg|jpeg|gif|pdf|doc|txt|ico|rss|zip|mp3|rar|exe|wmv|doc|avi|ppt|mpg|mpeg|tif|wav|mov|psd|ai|xls|mp4|m4a|swf|dat|dmg|iso|flv|m4v|torrent|ttf|woff|svg|eot)$/i;
+
+export const handler = async (
+  event: CloudFrontRequestEvent
+): Promise<CloudFrontRequest> => {
+  let request = event.Records[0].cf.request;
+
+  // If the request is from a bot, is not a file and is not from prerender
+  // then set the x-request-prerender header so the origin-request lambda function
+  // alters the origin to prerender.io
+  if (
+    !IS_FILE.test(request.uri) &&
+    IS_BOT.test(request.headers["user-agent"][0].value) &&
+    !request.headers["x-prerender"]
+  ) {
+    request.headers["x-request-prerender"] = [
+      {
+        key: "x-request-prerender",
+        value: "true",
+      },
+    ];
+
+    request.headers["x-prerender-host"] = [
+      { key: "X-Prerender-Host", value: request.headers.host[0].value },
+    ];
+  }
+
+  return request;
+};

packages/lambda-at-edge-handlers/lib/prerender-handler.ts → packages/lambda-at-edge-handlers/lib/prerender.ts

@@ -4,15 +4,16 @@ import {
   CloudFrontRequestEvent,
   CloudFrontResponse,
 } from "aws-lambda";
+
 const PRERENDER_TOKEN = process.env.PRERENDER_TOKEN
   ? process.env.PRERENDER_TOKEN
-  : "undef";
+  : "undefined";
 const PATH_PREFIX = process.env.PATH_PREFIX;
 const PRERENDER_URL = process.env.PRERENDER_URL
   ? process.env.PRERENDER_URL
   : "service.prerender.io";
 
-export const prerenderHandler = async (
+export const handler = async (
   event: CloudFrontRequestEvent
 ): Promise<CloudFrontResponse | CloudFrontRequest> => {
   let request = event.Records[0].cf.request;

packages/lambda-at-edge-handlers/lib/redirect.ts

@@ -0,0 +1,34 @@
+import 'source-map-support/register';
+import { CloudFrontRequestEvent, CloudFrontResponse, CloudFrontRequest } from 'aws-lambda';
+
+const REDIRECT_HOST = process.env.REDIRECT_HOST;
+const SUPPORTED_REGIONS = new RegExp(process.env.SUPPORTED_REGIONS);
+const DEFAULT_REGION = process.env.DEFAULT_REGION;
+
+export const handler = async (event: CloudFrontRequestEvent): Promise<CloudFrontResponse|CloudFrontRequest> => {
+     let request = event.Records[0].cf.request;
+
+     let redirectURL = `https://${REDIRECT_HOST}/`;
+     if (request.headers['cloudfront-viewer-country']) {
+          const countryCode = request.headers['cloudfront-viewer-country'][0].value;
+          if (SUPPORTED_REGIONS.test(countryCode)) {
+               redirectURL = `${redirectURL}${countryCode.toLowerCase()}${request.uri}`;
+          } else {
+               redirectURL = `${redirectURL}${DEFAULT_REGION.toLowerCase()}${request.uri}`;
+          }
+
+          return {
+               status: '302',
+               statusDescription: 'Found',
+               headers: {
+                    location: [{
+                         key: 'Location',
+                         value: redirectURL,
+                    }],
+               },
+          };
+     }
+
+     return request;
+
+}

packages/lambda-at-edge-handlers/package.json

@@ -21,6 +21,7 @@
   "dependencies": {
     "@types/aws-lambda": "^8.10.77",
     "esbuild": "0.12.15",
-    "source-map-support": "^0.5.16"
+    "source-map-support": "^0.5.16",
+    "axios": "^0.21.1"
   }
 }