Looked for a good way to start our Monday off here and after a good few months of work across many amazing folks and teams, excited to share the news!
A couple of years ago, AWS’s Open Source Strategy & Marketing and Open Data groups stepped in at a crucial moment to help our community and the NixOS Foundation cover a budget gap—donating thousands of dollars in AWS credits to keep our binary cache at cache.nixos.org online. Since then, they’ve renewed that support for the 2023 and 2024 fiscal years. For 2025, AWS is committing to the partnership again, covering the full cost of hosting cache.nixos.org.
A Look Back: Our S3 Journey
So, what is this cache?
The Nix binary cache is the ground truth for delivering signed and verified Nix build artifacts. It primarily provides prebuilt packages from nixpkgs, so you don’t have to build everything from source. This way when you go to install software with Nix you are downloading ready-made binaries from the cache. It’s the authoritative source for Nix builds. If the binary cache wouldn’t exist, users of Nix would have to build the packages they use from source. This can take many days of time and gigabytes of storage and memory, which not everybody has available. Without cache.nixos.org, most Nix-based workflows would grind to a halt.
Origins: After LogicBlox’s sponsorship ended, our community got together to help find a resolution. AWS stepped in to fund our S3 buckets, ensuring that cache.nixos.org and releases.nixos.org stayed online and performant. First post on this from 2023 - NixOS S3 Short Term Resolution!
Community Effort: We worked closely with AWS Open Source (shout-out to Mila and the OS Strategy team!), the Nix Infra team, a bunch of community members, ran community surveys, and gathered real-world usage data to build a strong case for sponsorship.
The Numbers Behind the Need
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Weekly Traffic: Nearly 1 PB/week served via Fastly’s CDN.
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AWS-Originated Egress: Since June 2022, AWS users have fetched 34.05 PB (~46.3 TB/day) from our CDN—more than any other cloud provider.
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Current Monthly Spend: $15,743.51 on S3 storage , egress and API calls.
These figures underscore both our ecosystem’s rapid adoption and the urgency of long-term cost controls.
Impact of the Increased Sponsorship & Next Steps
AWS’ support frees the Infra team to focus on durable fixes rather than day-to-day firefighting. More important, it gives us headroom for much more ambitious work - like better compression, new mirroring options, and partnering opportunities.
With our generous allocation of credits from AWS, we can continue running our cache unimpeded while the infra team considers other sustainability measures, such as:
- Optimizing the storage tiers used by the bucket using Intelligent Tiering to save on S3 storage cost #728
- Tweaking caching parameters of Fastly for more aggressive caching to save on S3 egress bandwidth cost #727
- Caching of 404s in fastly for faster substitution and to save on S3 API Call cost #769
- Garbage collection of older and unreferenced NARs to reduce storage
- Explore opportunities of deduplication between NARs with https://snix.dev
A large number of companies are also using Nix and AWS together, from the giant banks, to AWS itself and obviously even Flox! If you are interested in sharing your AWS + Nix story with us, drop me a note as it helps the effort in general! And if you’re interested to help/volunteer for any of the efforts please reach out!
Thank You!
We’re grateful to Nix supporters everywhere, too. None of this matters without you. I continue to be impressed with how people in our community step up to test solutions, measure performance, and share data, helping us stay focused on what matters. When it counts, the Nix community shows up. Thank you. Looking forward to seeing you at NixCon in September!
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AWS Open Source team (especially Mila, Spot, Hannah and Dave!)
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@lovesegfault , @fricklerhandwerk, @arianvp, @edef, @hexa, @tomberek , @infinisil, @ra33it0, @lassulus, @ryantrinkle, @rossturk, Steve
Looking forward to doing some more amazing work together <3.