[tasn]

Having maintained a service that uses Lambda. I think Lambda is probably fine for one-shot tasks, or taking from a queue (which is what it was built for), but I would never use it for API endpoints.

The main issues: 1. Unpredictable performance - latency (with cold start), concurrency limits (how quickly can we scale to X concurrent requests), etc? We spent many hours with AWS support before moving away from lambda. 2. Short running process are terrible in many ways - no DB connection pooling, no in memory cache.

I'd be much more happy if AWS fixed scale-up speed of ECS tasks so you can scale up your services in a reasonable time, than having these one-shot tasks.

[suzzer99]

Our app is mostly hit during business hours. So we wrote a pinger to "wake up" the back end lambdas when a user visits the website (not log in, just hit the site anywhere) *and* it's been more than 5 minutes since the last ping. It's not perfect but it helps a lot with the cold start times.

[tasn]

Our problem wasn't with zero traffic cold starts (nothing is calling the Lambda), but rather with scaling up cold starts (oh damn, traffic! We need more lambdas!).