feat: overhaul error handling

deal with most hanging request issues (#193)

* Improve boom error handling to make sure requests don't hang

* Overhaul error handling

* Update package lock and run linting

Co-authored-by: ryan lee <rol@bluetel.co.uk>

Author: ryanolee

package-lock.json

@@ -48,13 +48,12 @@
   ],
   "dependencies": {
     "body-parser": "^1.19.0",
-    "boom": "^7.3.0",
     "connect": "^3.7.0",
     "cookie-parser": "^1.4.5",
     "flat-cache": "^1.3.2",
     "fs-extra": "^9.0.0",
     "glob-to-regexp": "^0.4.1",
-    "http-status-codes": "^1.4.0"
+    "http-status-codes": "^2.1.4"
   },
   "devDependencies": {
     "@commitlint/cli": "^8.2.0",
@@ -66,7 +65,6 @@
     "@semantic-release/release-notes-generator": "^7.3.0",
     "@types/aws-lambda": "^8.10.51",
     "@types/body-parser": "^1.19.0",
-    "@types/boom": "^7.2.1",
     "@types/connect": "^3.4.32",
     "@types/cookie-parser": "^1.4.2",
     "@types/fs-extra": "^9.0.1",

package.json

@@ -1,15 +1,14 @@
 import { Context } from 'aws-lambda';
 import bodyParser from 'body-parser';
-import { isBoom } from 'boom';
-import * as Boom from 'boom';
 import connect, { HandleFunction } from 'connect';
 import cookieParser from 'cookie-parser';
 import * as fs from 'fs-extra';
 import { createServer, IncomingMessage, ServerResponse } from 'http';
-import { NOT_FOUND, OK } from 'http-status-codes';
+import { StatusCodes } from 'http-status-codes';
 import * as os from 'os';
 import * as path from 'path';
 import { URL } from 'url';
+import { HttpError, InternalServerError } from './errors/http';
 
 import { FunctionSet } from './function-set';
 import { asyncMiddleware, cloudfrontPost } from './middlewares';
@@ -92,7 +91,7 @@ export class BehaviorRouter {
 				if ((req.method || '').toUpperCase() === 'PURGE') {
 					await this.purgeStorage();
 
-					res.statusCode = OK;
+					res.statusCode = StatusCodes.OK;
 					res.end();
 					return;
 				}
@@ -101,7 +100,7 @@ export class BehaviorRouter {
 				const cfEvent = convertToCloudFrontEvent(req, this.builder('viewer-request'));
 
 				if (!handler) {
-					res.statusCode = NOT_FOUND;
+					res.statusCode = StatusCodes.NOT_FOUND;
 					res.end();
 					return;
 				}
@@ -111,7 +110,7 @@ export class BehaviorRouter {
 					const response = await lifecycle.run(req.url as string);
 
 					if (!response) {
-						throw Boom.internal();
+						throw new InternalServerError('No response set after full request lifecycle');
 					}
 
 					res.statusCode = parseInt(response.status, 10);
@@ -127,10 +126,8 @@ export class BehaviorRouter {
 
 					res.end(response.body);
 				} catch (err) {
-					if (isBoom(err)) {
-						this.handleError(err, res);
-						return;
-					}
+					this.handleError(err, res);
+					return;
 				}
 			}));
 
@@ -147,11 +144,19 @@ export class BehaviorRouter {
 		}
 	}
 
-	public handleError(err: Boom<any>, res: ServerResponse) {
-		res.statusCode = err.output.statusCode;
-		res.statusMessage = err.output.payload.error;
+	// Format errors
+	public handleError(err: HttpError, res: ServerResponse) {
+		res.statusCode = err.statusCode || StatusCodes.INTERNAL_SERVER_ERROR;
+
+		const payload = JSON.stringify(err.hasOwnProperty('getResponsePayload') ?
+			err.getResponsePayload() :
+			{
+				code: StatusCodes.INTERNAL_SERVER_ERROR,
+				message: err.stack || err.message
+			}
+		);
 
-		res.end(err.message);
+		res.end(payload);
 	}
 
 	public async purgeStorage() {

src/behavior-router.ts

@@ -0,0 +1,34 @@
+import { getReasonPhrase } from 'http-status-codes';
+
+interface HttpErrorResponse {
+	code: number;
+	message: string;
+}
+
+export class HttpError extends Error {
+	public statusCode: number;
+	public message: string;
+	public reasonPhrase: string|number;
+	public originalError: Error|null;
+
+	constructor(message: string, statusCode: number, originalError: Error|null = null) {
+		super(message);
+		this.message = message;
+		this.statusCode = statusCode;
+
+		try {
+			this.reasonPhrase = getReasonPhrase(statusCode);
+		} catch {
+			this.reasonPhrase = 'Unknown';
+		}
+
+		this.originalError = originalError;
+	}
+
+	public getResponsePayload(): HttpErrorResponse {
+		return {
+			code: this.statusCode,
+			message: this.message
+		};
+	}
+}

src/errors/http/http.error.ts

@@ -0,0 +1,3 @@
+export * from './internal-server.error';
+export * from './not-found.error';
+export * from './http.error';

src/errors/http/index.ts

@@ -0,0 +1,8 @@
+import { StatusCodes } from 'http-status-codes';
+import { HttpError } from './http.error';
+
+export class InternalServerError extends HttpError {
+	constructor(message: string, lastError: Error|null = null) {
+		super(message, StatusCodes.INTERNAL_SERVER_ERROR, lastError);
+	}
+}

src/errors/http/internal-server.error.ts

@@ -0,0 +1,8 @@
+import { StatusCodes } from 'http-status-codes';
+import { HttpError } from './http.error';
+
+export class NotFoundError extends HttpError {
+	constructor(message: string, lastError: Error|null = null) {
+		super(message, StatusCodes.NOT_FOUND, lastError);
+	}
+}

src/errors/http/not-found.error.ts

@@ -56,6 +56,11 @@ export class FunctionSet {
 
 		const handler = async (event: CloudFrontRequestEvent, context: Context) => {
 			const promise = new CallbackPromise();
+
+			if (typeof fn !== 'function') {
+				throw new Error(`Unable to find request handler under path: ${fn}. Please recheck your serverless.yml / exported handlers!`);
+			}
+
 			const result = fn(event, context, promise.callback) as CloudFrontRequestResult;
 
 			if (result instanceof Promise) {

src/function-set.ts

@@ -1,5 +1,4 @@
 import { CloudFrontRequest, CloudFrontRequestEvent, CloudFrontResultResponse } from 'aws-lambda';
-import * as Boom from 'boom';
 import * as fs from 'fs-extra';
 import * as http from 'http';
 import * as https from 'https';
@@ -8,6 +7,8 @@ import * as path from 'path';
 import { parse } from 'url';
 import { toHttpHeaders } from '../utils';
 import { OutgoingHttpHeaders } from 'http';
+import { InternalServerError, NotFoundError } from '../errors/http';
+import { StatusCodes } from 'http-status-codes';
 
 
 export class Origin {
@@ -36,7 +37,7 @@ export class Origin {
 
 			return {
 				status: '200',
-				statusDescription: '',
+				statusDescription: 'OK',
 				headers: {
 					'content-type': [
 						{ key: 'content-type', value: 'application/json' }
@@ -46,16 +47,23 @@ export class Origin {
 				body: contents
 			};
 		} catch (err) {
-			if (err instanceof Boom.notFound) {
-				return {
-					status: '404'
-				};
-			} else {
-				return {
-					status: '500',
-					statusDescription: err.message
-				};
-			}
+			// Make sure error gets back to user
+			const status = err.statusCode || StatusCodes.INTERNAL_SERVER_ERROR;
+			const reasonPhrase = err.reasonPhrase || 'Internal Server Error';
+			return {
+				status: status,
+				statusDescription: reasonPhrase,
+				headers: {
+					'content-type': [
+						{ key: 'content-type', value: 'application/json' }
+					]
+				},
+				bodyEncoding: 'text',
+				body: JSON.stringify({
+					'code': status,
+					'message': err.message
+				})
+			};
 		}
 	}
 
@@ -68,13 +76,13 @@ export class Origin {
 			}
 			case 'http':
 			case 'https': {
-				return this.getHttpResource(request);
+				return await this.getHttpResource(request);
 			}
 			case 'noop': {
-				throw Boom.notFound();
+				throw new NotFoundError('Operation given as \'noop\'');
 			}
 			default: {
-				throw Boom.internal('Invalid origin type');
+				throw new InternalServerError('Invalid request type (needs to be \'http\', \'https\' or \'file\')');
 			}
 		}
 	}
@@ -83,6 +91,20 @@ export class Origin {
 		const uri = parse(key);
 		const fileName = uri.pathname;
 
+		const fileTarget = `${this.baseUrl}/${fileName}`;
+
+		// Check for if path given is accessible and is a file before fetching it
+		try {
+			await fs.access(fileTarget);
+		} catch {
+			throw new NotFoundError(`File ${fileTarget} does not exist`);
+		}
+
+		const fileState = await fs.lstat(fileTarget);
+		if (!fileState.isFile()) {
+			throw new NotFoundError(`${fileTarget} is not a file.`);
+		}
+
 		return await fs.readFile(`${this.baseUrl}/${fileName}`, 'utf-8');
 	}