feat: lay groundwork for different event sources

rename middleware from x-apigateway to x-lambda
CodeGenieApp · Apr 29, 2019 · 2db86f2 · 2db86f2
1 parent 149b14a
commit 2db86f2
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Showing 6 changed files with 92 additions and 53 deletions.
diff --git a/README.md b/README.md
@@ -41,7 +41,7 @@ This package includes middleware to easily get the event object Lambda receives
 const awsServerlessExpressMiddleware = require('aws-serverless-express/middleware')
 app.use(awsServerlessExpressMiddleware.eventContext())
 app.get('/', (req, res) => {
-  res.json(req.apiGateway.event)
+  res.json(req.lambda.event)
 })
 ```
 

diff --git a/__tests__/middleware.js b/__tests__/middleware.js
@@ -5,14 +5,14 @@ const mockNext = () => true
 const generateMockReq = () => {
   return {
     headers: {
-      'x-apigateway-event': encodeURIComponent(JSON.stringify({
+      'x-lambda-event': encodeURIComponent(JSON.stringify({
         path: '/foo/bar',
         queryStringParameters: {
           foo: '🖖',
           bar: '~!@#$%^&*()_+`-=;\':",./<>?`'
         }
       })),
-      'x-apigateway-context': encodeURIComponent(JSON.stringify({foo: 'bar'}))
+      'x-lambda-context': encodeURIComponent(JSON.stringify({foo: 'bar'}))
     }
   }
 }
@@ -24,10 +24,10 @@ test('defaults', () => {
 
   eventContextMiddleware()(req, mockRes, mockNext)
 
-  expect(req.apiGateway.event).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-apigateway-event'])))
-  expect(req.apiGateway.context).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-apigateway-context'])))
-  expect(req.headers['x-apigateway-event']).toBe(undefined)
-  expect(req.headers['x-apigateway-context']).toBe(undefined)
+  expect(req.lambda.event).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-lambda-event'])))
+  expect(req.lambda.context).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-lambda-context'])))
+  expect(req.headers['x-lambda-event']).toBe(undefined)
+  expect(req.headers['x-lambda-context']).toBe(undefined)
 })
 
 test('options.reqPropKey', () => {
@@ -36,10 +36,10 @@ test('options.reqPropKey', () => {
 
   eventContextMiddleware({ reqPropKey: '_apiGateway' })(req, mockRes, mockNext)
 
-  expect(req._apiGateway.event).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-apigateway-event'])))
-  expect(req._apiGateway.context).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-apigateway-context'])))
-  expect(req.headers['x-apigateway-event']).toBe(undefined)
-  expect(req.headers['x-apigateway-context']).toBe(undefined)
+  expect(req._apiGateway.event).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-lambda-event'])))
+  expect(req._apiGateway.context).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-lambda-context'])))
+  expect(req.headers['x-lambda-event']).toBe(undefined)
+  expect(req.headers['x-lambda-context']).toBe(undefined)
 })
 
 test('options.deleteHeaders = false', () => {
@@ -48,26 +48,26 @@ test('options.deleteHeaders = false', () => {
 
   eventContextMiddleware({ deleteHeaders: false })(req, mockRes, mockNext)
 
-  expect(req.apiGateway.event).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-apigateway-event'])))
-  expect(req.apiGateway.context).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-apigateway-context'])))
-  expect(req.headers['x-apigateway-event']).toEqual(originalHeaders['x-apigateway-event'])
-  expect(req.headers['x-apigateway-context']).toEqual(originalHeaders['x-apigateway-context'])
+  expect(req.lambda.event).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-lambda-event'])))
+  expect(req.lambda.context).toEqual(JSON.parse(decodeURIComponent(originalHeaders['x-lambda-context'])))
+  expect(req.headers['x-lambda-event']).toEqual(originalHeaders['x-lambda-event'])
+  expect(req.headers['x-lambda-context']).toEqual(originalHeaders['x-lambda-context'])
 })
 
-test('Missing x-apigateway-event', () => {
+test('Missing x-lambda-event', () => {
   const req = generateMockReq()
-  delete req.headers['x-apigateway-event']
+  delete req.headers['x-lambda-event']
 
   eventContextMiddleware({ deleteHeaders: false })(req, mockRes, mockNext)
 
-  expect(req.apiGateway).toBe(undefined)
+  expect(req.lambda).toBe(undefined)
 })
 
-test('Missing x-apigateway-context', () => {
+test('Missing x-lambda-context', () => {
   const req = generateMockReq()
-  delete req.headers['x-apigateway-context']
+  delete req.headers['x-lambda-context']
 
   eventContextMiddleware({ deleteHeaders: false })(req, mockRes, mockNext)
 
-  expect(req.apiGateway).toBe(undefined)
+  expect(req.lambda).toBe(undefined)
 })
diff --git a/__tests__/unit.js b/__tests__/unit.js
@@ -72,8 +72,8 @@ test('mapApiGatewayEventToHttpRequest: with headers', () => {
     headers: {
       'x-foo': 'foo',
       'Content-Length': Buffer.byteLength('Hello serverless!'),
-      'x-apigateway-event': encodeURIComponent(JSON.stringify(r.eventClone)),
-      'x-apigateway-context': encodeURIComponent(JSON.stringify(r.context))
+      'x-lambda-event': encodeURIComponent(JSON.stringify(r.eventClone)),
+      'x-lambda-context': encodeURIComponent(JSON.stringify(r.context))
     },
     socketPath: '/tmp/server0.sock'
   })
@@ -87,8 +87,8 @@ test('mapApiGatewayEventToHttpRequest: without headers', () => {
     path: '/foo',
     headers: {
       'Content-Length': Buffer.byteLength('Hello serverless!'),
-      'x-apigateway-event': encodeURIComponent(JSON.stringify(r.eventClone)),
-      'x-apigateway-context': encodeURIComponent(JSON.stringify(r.context))
+      'x-lambda-event': encodeURIComponent(JSON.stringify(r.eventClone)),
+      'x-lambda-context': encodeURIComponent(JSON.stringify(r.context))
     },
     socketPath: '/tmp/server0.sock'
   })

diff --git a/examples/basic-starter/app.js b/examples/basic-starter/app.js
@@ -4,7 +4,7 @@ const express = require('express')
 const bodyParser = require('body-parser')
 const cors = require('cors')
 const compression = require('compression')
-const awsServerlessExpressMiddleware = require('aws-serverless-express/middleware')
+const awsServerlessExpressMiddleware = require(process.env.NODE_ENV === 'test' ? '../../middleware' : 'aws-serverless-express/middleware')
 const app = express()
 const router = express.Router()
 
@@ -28,7 +28,7 @@ app.set('views', path.join(__dirname, 'views'))
 
 router.get('/', (req, res) => {
   res.render('index', {
-    apiUrl: req.apiGateway ? `https://${req.apiGateway.event.headers.Host}/${req.apiGateway.event.requestContext.stage}` : 'http://localhost:3000'
+    apiUrl: req.lambda ? `https://${req.lambda.event.headers.Host}/${req.lambda.event.requestContext.stage}` : 'http://localhost:3000'
   })
 })
 

diff --git a/src/index.js b/src/index.js
@@ -42,20 +42,17 @@ function isContentTypeBinaryMimeType ({ contentType, binaryMimeTypes }) {
   return binaryMimeTypes.length > 0 && !!isType.is(contentType, binaryMimeTypes)
 }
 
-function mapApiGatewayEventToHttpRequest ({ event, context, socketPath }) {
-  const headers = Object.assign({}, event.headers)
-
-  // NOTE: API Gateway is not setting Content-Length header on requests even when they have a body
-  if (event.body && !headers['Content-Length']) {
-    const body = getEventBody({ event })
-    headers['Content-Length'] = Buffer.byteLength(body)
-  }
-
+function mapEventToHttpRequest ({
+  event,
+  context,
+  socketPath,
+  headers = Object.assign({}, event.headers)
+}) {
   const clonedEventWithoutBody = clone({ object: event })
   delete clonedEventWithoutBody.body
 
-  headers['x-apigateway-event'] = encodeURIComponent(JSON.stringify(clonedEventWithoutBody))
-  headers['x-apigateway-context'] = encodeURIComponent(JSON.stringify(context))
+  headers['x-lambda-event'] = encodeURIComponent(JSON.stringify(clonedEventWithoutBody))
+  headers['x-lambda-context'] = encodeURIComponent(JSON.stringify(context))
 
   return {
     method: event.httpMethod,
@@ -69,6 +66,30 @@ function mapApiGatewayEventToHttpRequest ({ event, context, socketPath }) {
   }
 }
 
+function mapApiGatewayEventToHttpRequest ({ event, context, socketPath }) {
+  const httpRequest = mapEventToHttpRequest({ event, context, socketPath })
+
+  // NOTE: API Gateway is not setting Content-Length header on requests even when they have a body
+  if (event.body && !httpRequest.headers['Content-Length']) {
+    const body = getEventBody({ event })
+    httpRequest.headers['Content-Length'] = Buffer.byteLength(body)
+  }
+
+  return httpRequest
+}
+
+function mapAlbEventToHttpRequest ({ event, context, socketPath }) {
+  const httpRequest = mapEventToHttpRequest({ event, context, socketPath })
+
+  // NOTE: API Gateway is not setting Content-Length header on requests even when they have a body
+  if (event.body && !httpRequest.headers['Content-Length']) {
+    const body = getEventBody({ event })
+    httpRequest.headers['Content-Length'] = Buffer.byteLength(body)
+  }
+
+  return httpRequest
+}
+
 function forwardResponseToApiGateway ({ server, response, resolver }) {
   let buf = []
 
@@ -150,14 +171,25 @@ function forwardLibraryErrorResponseToApiGateway ({ error, resolver }) {
   })
 }
 
+function getEventMapperBasedOnEventSource ({ eventSource }) {
+  switch (eventSource) {
+    case 'ALB':
+      return mapAlbEventToHttpRequest
+    default:
+      return mapApiGatewayEventToHttpRequest
+  }
+}
+
 function forwardRequestToNodeServer ({
   server,
   event,
   context,
-  resolver
+  resolver,
+  eventSource,
+  eventMapper = getEventMapperBasedOnEventSource({ eventSource })
 }) {
   try {
-    const requestOptions = mapApiGatewayEventToHttpRequest({
+    const requestOptions = eventMapper({
       event,
       context,
       socketPath: getSocketPath({ socketPathSuffix: server._socketPathSuffix })
@@ -220,8 +252,10 @@ function createServer ({
 }
 
 function getEventSourceBasedOnEvent ({
-  eventSource
+  event
 }) {
+  if (event && event.requestContext && event.requestContext.elb) return 'ALB'
+
   return 'API_GATEWAY'
 }
 
@@ -252,15 +286,17 @@ function proxy ({
           server,
           event,
           context,
-          resolver
+          resolver,
+          eventSource
         })
       } else {
         startServer({ server })
           .on('listening', () => forwardRequestToNodeServer({
             server,
             event,
             context,
-            resolver
+            resolver,
+            eventSource
           }))
       }
     })
@@ -287,7 +323,8 @@ function makeResolver ({
 function configure ({
   app: configureApp,
   binaryMimeTypes: configureBinaryMimeTypes = [],
-  resolutionMode: configureResolutionMode = 'CONTEXT_SUCCEED'
+  resolutionMode: configureResolutionMode = 'CONTEXT_SUCCEED',
+  eventSource
 } = {}) {
   function _createServer ({
     app = configureApp,
@@ -306,14 +343,16 @@ function configure ({
     resolutionMode = configureResolutionMode,
     event,
     context,
-    callback
+    callback,
+    eventSource
   } = {}) {
     return proxy({
       server,
       event,
       context,
       resolutionMode,
-      callback
+      callback,
+      eventSource
     })
   }
 

diff --git a/src/middleware.js b/src/middleware.js
@@ -1,21 +1,21 @@
 module.exports.eventContext = ({
-  reqPropKey = 'apiGateway',
+  reqPropKey = 'lambda',
   deleteHeaders = true
 } = {}) => function apiGatewayEventParser (req, res, next) {
-  if (!req.headers['x-apigateway-event'] || !req.headers['x-apigateway-context']) {
-    console.error('Missing x-apigateway-event or x-apigateway-context header(s)')
+  if (!req.headers['x-lambda-event'] || !req.headers['x-lambda-context']) {
+    console.error('Missing x-lambda-event or x-lambda-context header(s)')
     next()
     return
   }
 
   req[reqPropKey] = {
-    event: JSON.parse(decodeURIComponent(req.headers['x-apigateway-event'])),
-    context: JSON.parse(decodeURIComponent(req.headers['x-apigateway-context']))
+    event: JSON.parse(decodeURIComponent(req.headers['x-lambda-event'])),
+    context: JSON.parse(decodeURIComponent(req.headers['x-lambda-context']))
   }
 
   if (deleteHeaders) {
-    delete req.headers['x-apigateway-event']
-    delete req.headers['x-apigateway-context']
+    delete req.headers['x-lambda-event']
+    delete req.headers['x-lambda-context']
   }
 
   next()