This is how a conversation with a colleague who were enthusiastic about Serverless, and who's company was mostly on Java/JVM stack went:
Colleague: Lambda is awesome, we can scale down to zero and lower costs! We love it! We use cool tech!!
Me: What did you do about JVM warm up?
Colleague: We solved it by having a keepalive daemon which pings the service to keep it always warmed up.
... Me thinking: Uhh, but what about scale down to zero?
Me: What do you do about pricing when your service grows?
Colleague: We use it only for small services.
... Me thinking: Uhh, start small and STAY SMALL?
Me: How was performance?
Colleague: It was on average 100ms slower than a regular service, but it was OK since it was a small service anyway.
... Me thinking: Uhh, but what about services who _depend_ on this small service, who now have additional 100ms times to comprehend with?
Overall, I think his answers were self explanatory. Lambda seems to be a fast prototyping tool. When your service grows, it's time to think how to get out.
Colleague: Lambda is awesome, we can scale down to zero and lower costs! We love it! We use cool tech!!
Me: What did you do about JVM warm up?
Colleague: We solved it by having a keepalive daemon which pings the service to keep it always warmed up.
... Me thinking: Uhh, but what about scale down to zero?
Me: What do you do about pricing when your service grows?
Colleague: We use it only for small services.
... Me thinking: Uhh, start small and STAY SMALL?
Me: How was performance?
Colleague: It was on average 100ms slower than a regular service, but it was OK since it was a small service anyway.
... Me thinking: Uhh, but what about services who _depend_ on this small service, who now have additional 100ms times to comprehend with?
Overall, I think his answers were self explanatory. Lambda seems to be a fast prototyping tool. When your service grows, it's time to think how to get out.