About

This was used to test whether using environment variables in Lambda impact coldstarts. It runs a Lambda every 3 hours to test coldstart times. Here is the companion blog post.

Deployment

npm install
npx cdk deploy

Important files

• lib/coldstarter-stack.ts - Defines the stack
• src/coldstarter.js - The Lambda function that invokes the other lambda functions and emits latency logs
• src/handler.js - The Lambda function which has environment variables or not.

CloudWatch Insights Queries

To get Init Duration deltas run this on /aws/lambda/Function and /aws/lambda/FunctionWithEnv simultaneously:

filter ispresent(@initDuration) |
stats max(@initDuration)-min(@initDuration) as delta by bin(2h) | stats min(delta) as min, avg(delta) as avg, pct(delta,50) as p50, max(delta) as max

To get E2E latency deltas run this on /aws/lambda/Coldstarter:

filter ispresent(coldstart) and coldstart >0
| stats min(latency) as mi, max(latency) as ma by bin(2h) as bucket
| stats min(ma-mi) as min, avg(ma-mi) as avg, pct(ma-mi,50) as p50,pct(ma-mi,90) as p90, pct(ma-mi,95) as p95, max(ma-mi) as max

Useful commands

• npm run build compile typescript to js
• npm run watch watch for changes and compile
• npm run test perform the jest unit tests
• npx cdk deploy deploy this stack to your default AWS account/region
• npx cdk diff compare deployed stack with current state
• npx cdk synth emits the synthesized CloudFormation template