With each release of LLRT (Low Latency Runtime for Lambda), I've tried to use it to run my production API and failed. Recently I took a different approach and navigated the last few hurdles to migrate my API from Node 22 to LLRT. In this post, I'll share how I did it, the challenges I faced, and some benchmarks.
Last year I migrated the Speedrun API from the Serverless Framework V3 to the Cloud Development Kit (CDK). At the same time, I migrated from API Gateway to CloudFront. In this post I'll describe the process, provide a simple application for you to migrate to practice with and share some thoughts about Serverless V3 vs. CDK.
When I migrated the Speedrun API from API Gateway to CloudFront, I lost an important latency metric; End-to-End (E2E) API latency. Detailed CloudFront metrics provide this latency metric and a few others, but I was curious to see if I could get more granular. Could I get realtime origin latency by edge location, software version and whether there was a coldstart? Kind of. In this post, I'll show how I used CloudFront Functions and the Embedded Metrics Format (EMF) to obtain more insight into my end user latency.