Design and Implementation of Sprites

Summary

Image by Annie Ruygt Replacement-level homeowners buy boxes of pens and stick them in “the pen drawer”. What the elites know: you have to think adversarially about pens. “The purpose of a system is what it does”; a household’s is to uniformly distribute pens. Months from now, the drawer will be empty, no matter how many pens you stockpile. Instead, scatter pens every place you could possibly think to look for one — drawers, ledges, desks. Any time anybody needs a pen, several are at hand, in exactly the first place they look. This is the best way I’ve found to articulate the idea of Sprites, the platform we just launched at Fly.io. Sprites are ball-point disposable computers. Whatever mark you mean to make, we’ve rigged it so you’re never more than a second or two away from having a Sprite to do it with. Sprites are Linux virtual machines. You get root. They create in just a second or two: so fast, the experience of creating and shelling into one is identical to SSH'ing into a machine that already exists. Sprites all have a 100GB durable root filesystem. They put themselves to sleep automatically when inactive, and cost practically nothing while asleep. As a result, I barely feel the need to name my Sprites. Sometimes I’ll just type sprite create dkjsdjk and start some task. People at Fly.io who use Sprites have dozens hanging around. There aren’t yet many things in cloud computing that have the exact shape Sprites do: Instant creation No time limits Persistent disk Auto-sleep to a cheap inactive state This is a post about how we managed to get this working. We created a new orchestration stack that undoes some of the core decisions we made for Fly Machines, our flagship product. Turns out, these new decisions make Sprites drastically easier for us to scale and manage. We’re pretty psyched. Lucky for me, there happen to be three big decisions we made that get you 90% of the way from Fly Machines to Sprites, which makes this an easy post to write. So, without further...