NixCon 2025 - The Nix Binary Cache and AWS

Behind the Scenes of `cache.nixos.org`: Scaling Nix’s Binary Cache to Infinity

The Nix binary cache is the silent powerhouse of the Nix ecosystem: every day, it fields thousands of requests per second—amounting to nearly 6 billion requests per month!—for NixOS and Nix users worldwide. But what makes it work at scale, how—or why—is its simplicity a virtue, and how does an ongoing partnership between AWS and the Nix Foundation ensure its availability for years to come?

In this fireside chat, join Ron (Flox), Tarus (AWS), Tom Bereknyei and moderator Ross (Flox) for a conversation about:

What the Nix binary cache actually is…
…and why it matters for the community, reproducibility, and even the survival of historical software;
How AWS came to support `cache.nixos.org`
Why the binary cache’s “dumb” design is a feature, not a bug;
What goes in the cache?
Challenges and lessons learned: scaling, cost optimization, and keeping things simple
Why this partnership is important for the Nix ecosystem

Whether you’re a builder, a Nix maintainer, a user, or just curious about how open source infra runs at global scale, this conversation will offer insights, anecdotes, and a look at how communities and clouds can support each other.

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Speaker(s): Tarus Balog

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https://talks.nixcon.org/nixcon-2025/...

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5-7 September 2025
OST Rapperswill
Switzerland
https://2025.nixcon.org


Recording with support from Chaos West TV & C3VOC
Recording License: CC-BY-SA 4.0 (https://creativecommons.org/licenses/...)

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Music by tonstr.studio
https://tonstrstudio.bandcamp.com/alb...
Music License: CC-BY-SA 4.0 (https://creativecommons.org/licenses/...)