Code and Let Live

Summary

Image by Annie Ruygt The state of the art in agent isolation is a read-only sandbox. At Fly.io, we’ve been selling that story for years, and we’re calling it: ephemeral sandboxes are obsolete. Stop killing your sandboxes every time you use them. My argument won’t make sense without showing you something new we’ve built. We’re all adults here, this is a company, we talk about what we do. Here goes. So, I want to run some code. So what I do is, I run sprite create. While it operates, I’ll explain what’s happening behind the— Wrap text Copy to clipboard ✓ Created demo-123 sprite in 1.0s ● Connecting to console... sprite@sprite:~# Shit, it’s already there. That’s a root shell on a Linux computer we now own. It came online in about the same amount of time it would take to ssh into a host that already existed. We call these things “Sprites”. Let’s install FFmpeg on our Sprite: Wrap text Copy to clipboard sudo apt-get install -y ffmpeg >/dev/null 2>&1 Unlike creating the Sprite in the first place, installing ffmpeg with apt-get is dog slow. Let’s try not to have to do that again: Wrap text Copy to clipboard sprite@sprite:~# sprite-env checkpoints create # ... {"type":"complete","data":"Checkpoint v1 created successfully", "time":"2025-12-22T22:50:48.60423809Z"} This completes instantly. Didn’t even bother to measure. I step away to get coffee. Time passes. The Sprite, noticing my inactivity, goes to sleep. I meet an old friend from high school at the coffee shop. End up spending the day together. More time passes. Days even. Returning later: Wrap text Copy to clipboard > $ sprite console sprite@sprite:~# ffmpeg ffmpeg version 7.1.1-1ubuntu1.3 Copyright (c) 2000-2025 the FFmpeg developers Use -h to get full help or, even better, run 'man ffmpeg' sprite@sprite:~# Everything’s where I left it. Sprites are durable. 100GB capacity to start, no ceremony. Maybe I’ll keep it around a few more days, maybe a few months, doesn’t matter, just works. Say I get an application up on its ...