Feature/do 1607 feature environments

README.md

@@ -8,6 +8,7 @@ Construct | Description
 -- | --
 [basic-auth](packages/basic-auth) |
 [cloudfront-security-headers](packages/cloudfront-security-headers) |
+[feature-env-handlers](packages/feature-env-handlers) | Lambda@Edge handlers to support feature environments
 [geoip-redirect](packages/geoip-redirect) |
 [graphql-server](packages/graphql-server) |
 [lambda-at-edge-handlers](packages/lambda-at-edge-handlers) |

packages/feature-env-handlers/README.md

@@ -0,0 +1,11 @@
+# Feature Environment Lambda@Edge Handlers
+
+A collection of Lambda@Edge functions to handle routing in feature environments. 
+
+Feature environments are temporary environments that are created on a pull request. They function almost the same as regular statically hosted environments, however, there are multiple frontends hosted in the same bucket. Therefore, we require a method to route to the correct sub-path depending on which subdomain the user has visited. 
+
+# Common issues
+
+Error config must be **disabled** for these functions to work. See the below diagram for the reasoning. 
+
+![error config diagram](docs/error_config.png)

packages/feature-env-handlers/index.ts

@@ -0,0 +1,4 @@
+import { handler as OriginRequest } from "./lib/origin-request";
+import { handler as ViwerRequest } from "./lib/viewer-request";
+
+export { OriginRequest, ViwerRequest };

packages/feature-env-handlers/lib/origin-request.ts

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+import { CloudFrontRequestEvent, CloudFrontRequest } from "aws-lambda";
+import "source-map-support/register";
+
+const RETURN_INDEX = /(^.\w*$)|(\/$)|(\.html$)/i;
+
+export const handler = async (
+  event: CloudFrontRequestEvent
+): Promise<CloudFrontRequest> => {
+  const { request } = event.Records[0].cf;
+
+  const host = request.headers["x-forwarded-host"][0].value;
+  const matches = host.match(/^([^.]+)/);
+
+  if (matches) {
+    const branch = matches.pop();
+    if (request.origin?.s3) {
+      request.origin.s3.path = `/${branch}`;
+    }
+  }
+
+  if (RETURN_INDEX.test(request.uri)) {
+    request.uri = "/index.html";
+  }
+
+  return request;
+};

packages/feature-env-handlers/lib/viewer-request.ts

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+import { CloudFrontRequest, CloudFrontRequestEvent } from "aws-lambda";
+import "source-map-support/register";
+
+export const handler = async (
+  event: CloudFrontRequestEvent
+): Promise<CloudFrontRequest> => {
+  const { request } = event.Records[0].cf;
+
+  request.headers["x-forwarded-host"] = [
+    {
+      value: request.headers.host[0].value,
+      key: "X-Forwarded-Host",
+    },
+  ];
+
+  return request;
+};

packages/feature-env-handlers/package.json

@@ -0,0 +1,26 @@
+{
+  "name": "@aligent/cdk-feature-env-handlers",
+  "version": "0.1.0",
+  "description": "Cloudfront Lambda@Edge handlers to allow feature environments to function",
+  "main": "index.js",
+  "scripts": {
+    "build": "tsc",
+    "watch": "tsc -w",
+    "test": "echo \"No test specified\" && exit 0"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/aligent/aws-cdk-constructs.git"
+  },
+  "license": "GPL-3.0-only",
+  "bugs": {
+    "url": "https://github.com/aligent/cdk-constructs/issues"
+  },
+  "homepage": "https://github.com/aligent/cdk-constructs#readme",
+  "devDependencies": {
+    "@types/aws-lambda": "^8.10.122"
+  },
+  "dependencies": {
+    "source-map-support": "^0.5.21"
+  }
+}

packages/feature-env-handlers/tsconfig.json

@@ -0,0 +1,3 @@
+{
+  "extends": "../../tsconfig.json"
+}