In the world of reproducible computing, GNU Guix stands out as a pioneering distribution that enables bit-for-bit reproducible builds and a comprehensive package management system. However, building software from source for every package can be time-consuming and resource-intensive. This is where substitute servers play a crucial role, allowing users to download pre-built binary packages instead of compiling them locally.

Here we built a dedicated build farm and substitute server in just few lines of code!

Guix hands us the programmer's dream of deploying a full server with its services and orchestration as a program! Not only can the 'program' be adapted to other machines – across the planet – the deployment also benefits from Guix reproducibility guarantees, including natural roll-backs of full and partial deployment. The federated nature of these build farms is increasingly important - in fact, I invite you to roll-your-own based on this article.

In July 2024 I announced on the guix mailing list that a new North American based Guix substitute server and build farm, cuirass.genenetwork.org, was available for general use. Having a server in the USA increases the speed and reduces the latency for North American downloaders of Guix and all 20,000+ built free software packages. It also provides redundancy in case something happens with other substitute servers.