You thought you could just set some flags and your node.js lambda function would be bundled, tree-shaken, minified and go from ice cold to glowing hot in milliseconds? My sweet summer child. I thought that too, but then I analyzed the bundle, pored over some traces and realized how wrong I was. What follows is the rabbit hole I went down to optimize my lambda coldstarts.
How to log Hello World is taught, but how to log something useful isn't. Too often, developers add logging until their code works, then they forget about it. In this post I'll teach you how to instrument your code with request logs so when you have millions of users and production is going sideways, you know exactly what is going on.
I've learned several undocumented tricks log diving with CloudWatch Logs Insights. In this "Dropping the K" post I'll share some of my favorites.