© 2016, Amazon Web Services, Inc. or its Affiliates. All rights reserved.

Stefano Buliani, Specialist Solutions Architect, Serverless@sapessi

11/02/2016

Migrate Express Apps to ServerlessUsing AWS Lambda and Amazon API Gateway

Agenda

• Benefits of Amazon API Gateway• Benefits of AWS Lambda• API-first migration to the cloud• New features in API Gateway• aws-serverless-express in Github• Demo• Best practices

Benefits of Amazon API Gateway

Create a unified API frontend for multiple micro-

services

Authenticate and authorize

requests to a backend

DDoS protection and throttling for

your backend

Throttle, meter, and monetize API usage by 3rd party

developers

Code is all you need Event driven scaling

Never pay for idle Availability and fault tolerance built in

Benefits of AWS Lambda

Customer use case:API-first migration to the cloud

1. Use API Gateway to front existing backends

InternetClientAPI Gateway

Hosted service 1

Hosted service 2

AWS cloud

corporate data center

2. Lift & shift service to AWS

InternetClientAPI Gateway

Hosted service 1

Service 2on EC2

AWS cloud

corporate data center

3. Lift & re-architect

InternetClientAPI Gateway

Service 2on EC2

AWS cloud

Microservice 1

Microservice 2

Microservice 3

Re-architected Service 1

Simplified migration:New features in API Gateway

• Catch-all resource paths

• ANY http method

• PROXY integrations

Three new features in Amazon API Gateway

Roo

t /

/orders

GET

POST

/{id}GET

DELETE

/catalogue/GET

/{id} GET

Catch-all resource pathsDefine the entire API structure• Use path variables for individual

path parts: {id}• Use the Swagger toolkit to

generate documentation and SDKs

Roo

t /

/orders /{proxy+}

POST

GET

DELETE

/catalogue/ /{proxy+} GET

Quickly catch all sub-resources• Use catch-all paths to identify

separate services• Very quick to configure but less

well defined for doc and SDK generation

Catch-all resource paths – using Swagger

{ "Swagger": "2.0", … "paths": { "/{proxy+}": { … } }}

Roo

t /

/orders

GET

POST

/{id}GET

DELETE

/catalogue/GET

/{id} GET

ANY HTTP methodDefine methods individually• Flexible because each method

can use a different integration• Use the Swagger toolkit to

generate documentation and SDKs

Roo

t / /orders /{proxy+} ANY

/catalogue/ /{proxy+} ANY

Intercepts any HTTP verb• Very quick to configure but less

well defined for doc and SDK generation

• Works well with catch-all resource paths

ANY HTTP method – using Swagger{ "Swagger": "2.0", … "paths": { "/{proxy+}": { "x-amazon-apigateway-any-method": { … } } }}

Proxy integrations

HTTP_PROXY• No input/output mappings!• Sends entire request to the HTTP

backend and returns the unmodified response

AWS_PROXY• No input/output mappings!• Automatically generate event with

the entire request• Well defined return interface that

is automatically transformed into an HTTP response

Proxy integrationsR

oot / /orders/{path+} ANY

/catalogue/{path+} ANY

Store Lambda Function

HTTP service on EC2

Automatic request mapping{ resource: “/orders/{path+}”, path: “/orders/1423”, httpVerb: “GET”, headers: { “Content-Type”: “application/json”, “x-custom-header” : “1” }, queryStringParameters: { “limit”: 10 }, pathParameters: { “path”: “1423” }, requestContext: { “apiId”: “xxxxxx”, “apiKey”: “xxxxxxxxxxxxxxxxxxxx”, “identity”: { “sourceIp”: “xxx.xxx.xxx.xxx”, “cognitoIdentityId”: “xxxxxxxxxxx” } }, stageVariables: { } body : “”}

Default response structure{ statusCode: int, body: string, headers: { "Content-Type": "application/json", "x-Custom-Header" : “1" }};

Full request/response passthrough

Proxy integrations – using Swagger{ "Swagger": "2.0", … "paths": { "/{proxy+}": { "x-amazon-apigateway-any-method": { "x-amazon-apigateway-integration": { "type": ”aws_proxy" } } } }}

Roo

t /

/{proxy+} ANY Your Node.js Express app

The simplest possible API

Simple yet very powerful:

• Automatically scale to meet demand

• Only pay for the requests your receive

Using the API Gateway console

1. Select proxy resource when creating a new resource

Using the API Gateway console

1. The ANY method is created automatically2. Configure the integration

Running Express applications:The aws-serverless-express library

https://github.com/awslabs/aws-serverless-express

How it works

• AWS_PROXY integrations apply a default mapping to requests

• And expect a well defined return interface

Automatic request mapping{ resource: “/orders/{path+}”, path: “/orders/1423”, httpVerb: “GET”, headers: { “Content-Type”: “application/json”, “x-custom-header” : “1” }, queryStringParameters: { “limit”: 10 }, pathParameters: { “path”: “1423” }, requestContext: { }, stageVariables: { } body : “”}

Default response structure{ statusCode: int, body: string, headers: { "Content-Type": "application/json", "x-Custom-Header" : “1" }};

How it works

Mobile appsStart Lambda

functionAPI GatewayTransform

request into event JSON

aws-serverless-express receives the event

Express

If not started – start express server on local

socket

Transform event JSON into HTTP request and send it to local socket

Receive response from local socket and

transform it into return value

Your Express code executes

Transform return value into HTTP

response

Migrating an Express app

Five simple steps

1. Pull dependencies from npm (include aws-serverless-

express)

2. Create JavaScript wrapper

3. Zip folder contents including node-modules

4. Create Lambda function

5. Create API Gateway endpoint as proxy resource

The JavaScript wrapper

'use strict’const awsServerlessExpress = require('aws-serverless-express')const app = require('./app')const server = awsServerlessExpress.createServer(app)

exports.handler = (event, context) => { awsServerlessExpress.proxy(server, event, context)}

DEMO

Express on Serverless

• Automatically scales to

handle demand

• Only pay for requests

• Unit test your Express app

locally just like you do now

• Use your code and middlewares,

no changes required

We demoed Express, you can do the same with any framework / supported language

• Spring boot• Jersey• Flask• …

If you are starting from scratch, take a look at some serverless-native frameworks

• Serverless 1.0 - https://serverless.com/• Claudia.js - http://bit.ly/claudiajs• Chalice - http://bit.ly/aws-chalice• Zappa - http://bit.ly/py-zappa

Best practices

Using AWS Lambda

• 1:1 Mapping: Every API call triggers a stateless Lambda function - Each express

instance will only handle one requests at a time. Don’t worry too much about

concurrency

• Memory: CPU proportional to the memory configured - Increasing memory makes

your code execute and start faster (if CPU bound)

• Lazily load resources: The global scope helps you cache values, load them only

when you need them to avoid impacting startup time

• Offload tasks to the Gateway: Authorization and metering can be offloaded to

Amazon API Gateway. You can also use your middlewares in Express

Thank you!

Stefano Buliani@sapessi

AWS serverless Express libraryhttp://bit.ly/serverless-express

Proxy resources in API Gatewayhttp://bit.ly/proxy-resources-doc