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Starting a new software project? Check out Code Genie - aFull Stack App Generator that delivers a complete AWS Serverless project with source code, based on your data model. Including:

1. A React Next.js Web App hosted on Amplify Hosting
2. Serverless Express REST API running on API Gateway and Lambda
3. Cognito User Pools for Identity/Authentication
4. DynamoDB Database
5. Cloud Development Kit (CDK) for Infrastructure as Code (IAC)
6. Continuous Integration/Delivery (CI/CD) with GitHub Actions

Run REST APIs and other web applications using your existingNode.js application framework (Express, Koa, Hapi, Sails, etc.), on top ofAWS Lambda andAmazon API Gateway orAzure Function.

npm install @codegenie/serverless-express

Want to get up and running quickly?Check out our basic starter example that includes:

• Lambda function
• Express application
• Serverless Application Model (SAM)/CloudFormation template
• Helper scripts to configure, deploy, and manage your application

If you want to migrate an existing application to AWS Lambda, it's advised to get the minimal example up and running first, and then copy your application source in.

The only AWS Lambda specific code you need to write is a simple handler like below. All other code you can write as you normally do.

// lambda.jsconstserverlessExpress=require('@codegenie/serverless-express')constapp=require('./app')exports.handler=serverlessExpress({ app})

If your application needs to perform some common bootstrap tasks such as connecting to a database before the request is forward to the API, you can use the following pattern (also available inthis example):

// lambda.jsrequire('source-map-support/register')constserverlessExpress=require('@codegenie/serverless-express')constapp=require('./app')letserverlessExpressInstancefunctionasyncTask(){returnnewPromise((resolve)=>{setTimeout(()=>resolve('connected to database'),1000)})}asyncfunctionsetup(event,context){constasyncValue=awaitasyncTask()console.log(asyncValue)serverlessExpressInstance=serverlessExpress({ app})returnserverlessExpressInstance(event,context)}functionhandler(event,context){if(serverlessExpressInstance)returnserverlessExpressInstance(event,context)returnsetup(event,context)}exports.handler=handler

The only Azure Function specific code you need to write is a simpleindex.js and afunction.json like below.

// index.jsconstserverlessExpress=require('@codegenie/serverless-express')constapp=require('./app')constcachedServerlessExpress=serverlessExpress({ app})module.exports=asyncfunction(context,req){returncachedServerlessExpress(context,req)}

Theout-binding parameter"name": "$return" is important for Serverless Express to work.

// function.json{"bindings": [    {"authLevel":"anonymous","type":"httpTrigger","direction":"in","name":"req","route":"{*segments}"    },    {"type":"http","direction":"out","name":"$return"    }  ]}

1. Improved API - Simpler for end-user to use and configure.
2. Promise resolution mode by default. Can specifyresolutionMode to use"CONTEXT" or"CALLBACK"
3. Additional event sources - API Gateway V1 (REST API), API Gateway V2 (HTTP API), ALB, Lambda@Edge, VPC Lattice
4. Custom event source - If you have another event source you'd like to use that we don't natively support, check out theDynamoDB Example
5. Implementation uses mock Request/Response objects instead of running a server listening on a local socket. Thanks to @dougmoscrop fromhttps://github.com/dougmoscrop/serverless-http
6. AutomaticisBase64Encoded without specifyingbinaryMimeTypes. UsebinarySettings to customize. Thanks to @dougmoscrop fromhttps://github.com/dougmoscrop/serverless-http
7. respondWithErrors makes it easier to debug during development
8. Node.js 12+
9. Improved support for custom domain names

SeeUPGRADE.md to upgrade from aws-serverless-express and @codegenie/serverless-express 3.x

Determine if the response should be base64 encoded before being returned to the event source, for example, when returning images or compressed files. This is necessary due to API Gateway and other event sources not being capable of handling binary responses directly. The event source is then responsible for turning this back into a binary format before being returned to the client.

By default, this is determined based on thecontent-encoding andcontent-type headers returned by your application. If you need additional control over this, you can specifybinarySettings.

{binarySettings:{isBinary:({ headers})=>true,contentTypes:['image/*'],contentEncodings:[]}}

Any value you provide here should also be specified on API Gateway API. In SAM, this looks like:

ExpressApi:Type:AWS::Serverless::ApiProperties:StageName:prodBinaryMediaTypes:['image/*']

Lambda supports three methods to end the execution and return a result: context, callback, and promise. By default, serverless-express uses promise resolution, but you can specify 'CONTEXT' or 'CALLBACK' if you need to change this. If you specify 'CALLBACK', thencontext.callbackWaitsForEmptyEventLoop = false is also set for you.

serverlessExpress({  app,resolutionMode:'CALLBACK'})

Set this to true to have serverless-express include the error stack trace in the event of an unhandled exception. This is especially useful during development. By default, this is enabled whenNODE_ENV === 'development' so that the stack trace isn't returned in production.

serverless-express natively supports API Gateway, ALB, Lambda@Edge and VPC Lattice (only V2 events - event sourceAWS_VPC_LATTICE_V2). If you want to use Express with other AWS Services integrated with Lambda you can provide your own custom request/response mappings viaeventSource. See thecustom-mapper-dynamodb example.

functionrequestMapper({ event}){// Your logic here...return{    method,    path,    headers}}functionresponseMapper({  statusCode,  body,  headers,  isBase64Encoded}){// Your logic here...return{    statusCode,    body,    headers,    isBase64Encoded}}serverlessExpress({  app,eventSource:{getRequest:requestMapper,getResponse:responseMapper}})

A single function can be configured to handle additional kinds of AWS events:

• SNS
• DynamoDB Streams
• SQS
• EventBridge Events (formerlly CloudWatch Events)

Assuming the following function configuration inserverless.yml:

functions:lambda-handler:handler:src/lambda.handlerevents:      -http:path:/method:get      -sns:topicName:my-topic      -stream:type:dynamodbarn:arn:aws:dynamodb:us-east-1:012345678990:table/my-table/stream/2021-07-15T15:05:51.683      -sqs:arn:arn:aws:sqs:us-east-1:012345678990:myQueue      -eventBridge:pattern:source:              -aws.cloudformation

And the following configuration:

serverlessExpress({  app,eventSourceRoutes:{'AWS_SNS':'/sns','AWS_DYNAMODB':'/dynamodb','AWS_SQS':'/sqs''AWS_EVENTBRIDGE':'/eventbridge','AWS_KINESIS_DATA_STREAM':'/kinesis','AWS_S3':'/s3','AWS_STEP_FUNCTIONS':'/step-functions','AWS_SELF_MANAGED_KAFKA':'/self-managed-kafka',}})

Alternatively, to handle only SNS events (the keys in the map areoptional)

serverlessExpress({  app,eventSourceRoutes:{'AWS_SNS':'/sns',}})

Events willPOST to the routes configured.

Also, to ensure the events propagated from an internal event and not externally, it ishighly recommended toensure theHost header matches:

• SNS:sns.amazonaws.com
• DynamoDB:dynamodb.amazonaws.com
• SQS:sqs.amazonaws.com
• EventBridge:events.amazonaws.com
• KinesisDataStream:kinesis.amazonaws.com

Specify log settings that are passed to the default logger. Currently, you can only set the loglevel.

{logSettings:{level:'debug'// default: 'error'}}

Provide a customlog object withinfo,debug anderror methods. For example, you could override the default with aWinston log instance.

{log:{info(message,additional){console.info(message,additional)},debug(message,additional){console.debug(message,additional)},error(message,additional){console.error(message,additional)}}}

This package exposes a function to easily get theevent andcontext objects Lambda receives from the event source.

const{ getCurrentInvoke}=require('@codegenie/serverless-express')app.get('/',(req,res)=>{const{ event, context}=getCurrentInvoke()res.json(event)})

• Only pay for what you use
• No infrastructure to manage
• Auto-scaling with zero configuration
• Usage Plans
• Caching
• Authorization
• Staging
• SDK Generation
• API Monitoring
• Request Validation
• Documentation

npx loadtest --rps 100 -k -n 1500 -c 50 https://xxxx.execute-api.us-east-1.amazonaws.com/prod/users

On 11/30, the AWS Serverless Express library moved from AWS toVendia and will be rebranded to@codegenie/serverless-express. Similarly, theaws-serverless-express NPM package will be deprecated in favor of@codegenie/serverless-express.

Brett Andrews, the original creator of the Serverless Express library, will continue maintaining the repository and give it the attention and care it deserves. At the same time, we will be looking for additional contributors to participate in the development and stewardship of the Serverless Express library. AWS and theSAM team will remain involved in an administrative role alongside Vendia, Brett, and the new maintainers that will join the project.

We believe this is the best course of action to ensure that customers using this library get the best possible support in the future. To learn more about this move or become a maintainer of the new Serverless Express library, reach out to us through a GitHub issue on this repository.

Best,The AWS Serverless team, Brett & the Vendia team