What is awscdk-nodejsfunction-middy

This is a batteries-included starter project for using AWS CDK v2 with the NodejsFunction construct and Middy middleware engine for AWS Lambda. It comes equipped with the following:

Function URL feature for exposing your Lambdas to the internet via HTTP(S) endpoints (easily pluggable into API Gateway V2)
Invoke mode support for Function URL: BUFFERED or RESPONSE_STREAM
Lambda reserved concurrency and ephemeral storage config
CloudFront distribution support for the Function URL origin
WAF v2 enabled on the CloudFront distribution
Powertools for AWS Lambda (TypeScript) Idempotency with DynamoDB
Powertools for AWS Lambda (TypeScript) Logger
@Middy/http-router - which can route requests to nested handlers based on method and path of an http event
a number of Middy middleware including httpSecurityHeaders (based off Helmet.js)
AWS CodeDeploy deployment group
Lambda Insights layer
Provisioned concurrency config for alias
ARM64 or X86_64 archiitecture

Ideally, I'd recommend starting this deployment off in us-east-1 and then trying other regions.

You may want to change the AWS Lambda Powertools for TypeScript logging level from 'INFO' to 'DEBUG', 'WARN', or 'ERROR' as needed

It is recommended you modify your Function URL authentication type (NONE or IAM) and CORS policy as needed (or CloudFront distribution if using that instead):

// Function URL - MiddyStack.ts
const fnurl = LambdaNodeJsMiddy.addFunctionUrl({
  authType: FunctionUrlAuthType.NONE,
  cors: {
    allowedOrigins: ['*'],
    allowedMethods: [lambda.HttpMethod.ALL],
    allowedHeaders: ['Content-Type'],
    allowCredentials: true,
  },
});

You can also adjust your Node.js Lambda runtime config, reserved concurrency, storage and bundling minification as necessary:

// Create Lambda Function
const LambdaNodeJsMiddy = new NodejsFunction(this, 'LambdaNodeJsMiddy', {
  entry: join(__dirname, '..', '..', 'services', 'node-lambda', 'index.ts'),
  handler: 'handler',
  runtime: lambda.Runtime.NODEJS_20_X,
  memorySize: 1769,
  architecture: lambda.Architecture.ARM_64,
  timeout: Duration.minutes(5),
  reservedConcurrentExecutions: 60,
  environment: {
    IDEMPOTENCY_TABLE_NAME: props.idempotencyTable.tableName,
  },
  insightsVersion: lambda.LambdaInsightsVersion.fromInsightVersionArn(
    'arn:aws:lambda:us-east-1:580247275435:layer:LambdaInsightsExtension-Arm64:19'
  ),
  ephemeralStorageSize: Size.gibibytes(0.5),
  bundling: {
    minify: false,
  },
});

If you are experiencing issues when changing 'reservedConcurrentExecutions' check your AWS account quota limits, you may need to increase them through AWS Support

CodeDeploy deployment config can also be tuned as needed.

new aws_codedeploy.LambdaDeploymentGroup(this, 'DeploymentGroup', {
  alias,
  deploymentConfig: aws_codedeploy.LambdaDeploymentConfig.ALL_AT_ONCE,
});

DeploymentConfig options (CANARY and LINEAR): https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_codedeploy.LambdaDeploymentConfig.html

CloudFront with WAF

This CDK Stack enables the WAF v2 AWSManagedRulesCommonRuleSet managed rule group and associates it with the CloudFront distribution. For CLOUDFRONT, you must create your WAFv2 resources in the US East (N. Virginia) Region, us-east-1.

What is Middy

Middy (https://middy.js.org/) is a very simple middleware engine that allows you to simplify your AWS Lambda code when using Node.js.

If you have used web frameworks like Express, then you will be familiar with the concepts adopted in Middy and you will be able to get started very quickly.

A middleware engine allows you to focus on the strict business logic of your Lambda and then attach additional common elements like routing, validation, serialization, security headers etc. in a modular and reusable way by decorating the main business logic.

Currently the boilerplate handler comes equipped with the following:

const handler = middy()
  .use(httpEventNormalizer()) // this middleware normalizes the API Gateway, ALB, Function URLs, and VPC Lattice events
  .use(httpHeaderNormalizer()) // this middleware normalizes HTTP header names
  .use(jsonBodyParser()) // parses the request body when it's a JSON and converts it to an object
  .use(httpSecurityHeaders()) // applies best practice security headers to responses. It's a simplified port of HelmetJS.
  .use(httpErrorHandler()) // handles common http errors and returns proper responses
  .use(injectLambdaContext(logger));  // AWS Lambda Powertools for TypeScript Logger
  .handler(httpRouterHandler(routes)) // API Routes served by nested handlers