tl;dr: Move initialization logic outside of request handlers.

My team is building a new application, and I used CloudWatch alarms to understand what latency promises we could make without triggering the alarms too often. I set these alarms to fire when 3/3 datapoints breach the alarm’s threshold, and noticed an interesting pattern from multiple triggered alarms: A sharp increase in latency (hundreds of ms to multiple seconds), followed by a function timeout (30 seconds), again followed by a cold start.

Our application consists of a couple AWS Lambda functions and other serverless infrastructure, with a NodeJS 12 environment. One monolithic function backs an API Gateway endpoint. The Lambda function uses aws-serverless-koa for routing requests to the right handler, and the AWS SDK for JavaScript to call other AWS services like DynamoDB.

Prerequisites

This article assumes that you’ve already built a NodeJS application on AWS Lambda, and have some experience with the AWS CloudWatch service.

#aws #node #nodejs