DO-1410 lambda at edge Middleware

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

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+# These are some examples of commonly ignored file patterns.
+# You should customize this list as applicable to your project.
+# Learn more about .gitignore:
+#     https://www.atlassian.com/git/tutorials/saving-changes/gitignore
+
+# Node artifact files
+node_modules/
+dist/
+
+# Compiled Java class files
+*.class
+
+# Compiled Python bytecode
+*.py[cod]
+
+# Log files
+*.log
+
+# Package files
+*.jar
+
+# Maven
+target/
+dist/
+
+# JetBrains IDE
+.idea/
+
+# Unit test reports
+TEST*.xml
+
+# Generated by MacOS
+.DS_Store
+
+# Generated by Windows
+Thumbs.db
+
+# Applications
+*.app
+*.exe
+*.war
+
+# Large media files
+*.mp4
+*.tiff
+*.avi
+*.flv
+*.mov
+*.wmv
+
+!jest.config.js
+
+# CDK asset staging directory
+.cdk.staging
+cdk.out
+
+*.d.ts
+*.js

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

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+*.ts
+!lib/handlers/*.ts
+!*.d.ts
+!*.js
+
+# CDK asset staging directory
+.cdk.staging
+cdk.out
+
+# Samples
+sample/

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

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+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,
+  PrerenderCacheControlHandler,
+  PrerenderErrorResponseHandler,
+  PrerenderCheckHandler,
+  GeoIpRedirectHandler,
+};

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

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+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

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+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) => {
+        // Commenting this as there is body is not defined in the CloudFrontResponse type
+        // 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

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+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.ts

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+import "source-map-support/register";
+import {
+  CloudFrontRequest,
+  CloudFrontRequestEvent,
+  CloudFrontResponse,
+} from "aws-lambda";
+
+const PRERENDER_TOKEN = process.env.PRERENDER_TOKEN
+  ? process.env.PRERENDER_TOKEN
+  : "undefined";
+const PATH_PREFIX = process.env.PATH_PREFIX;
+const PRERENDER_URL = process.env.PRERENDER_URL
+  ? process.env.PRERENDER_URL
+  : "service.prerender.io";
+
+export const handler = async (
+  event: CloudFrontRequestEvent
+): Promise<CloudFrontResponse | CloudFrontRequest> => {
+  let request = event.Records[0].cf.request;
+
+  // viewer-request function will determine whether we prerender or not
+  // if we should we add prerender as our custom origin
+  if (request.headers["x-request-prerender"]) {
+    // Cloudfront will alter the request for / to /index.html
+    // since it is defined as the default root object
+    // we do not want to do this when prerendering the homepage
+    if (request.uri === `${PATH_PREFIX}/index.html`) {
+      request.uri = `${PATH_PREFIX}/`;
+    }
+
+    request.origin = {
+      custom: {
+        domainName: PRERENDER_URL,
+        port: 443,
+        protocol: "https",
+        readTimeout: 20,
+        keepaliveTimeout: 5,
+        sslProtocols: ["TLSv1", "TLSv1.1", "TLSv1.2"],
+        path: "/https%3A%2F%2F" + request.headers["x-prerender-host"][0].value,
+        customHeaders: {
+          "x-prerender-token": [
+            {
+              key: "x-prerender-token",
+              value: PRERENDER_TOKEN,
+            },
+          ],
+        },
+      },
+    };
+  } else {
+    request.uri = `${PATH_PREFIX}/index.html`;
+  }
+
+  return request;
+};