One presentation at NixCon 2017 that especially drew my attention was Nicolas Pierron‘s talk about Nixpkgs overlays (video, slides). I’d like to give a quick summary here for future reference. All the credits go to Nicolas, of course. Continue reading NixOS: The DOs and DON’Ts of nixpkgs overlays
NixOS manages dependencies in a very strict way—sometimes too strict? Here at Flying Circus, many users prefer to compile custom applications in home directories. They link them against libraries they have installed before by nix-env. This works well… until something is updated! On the next change anywhere down the dependency chain, libraries get new hashes in the Nix store, the garbage collector removes old versions, and user applications break until recompiled.
In this blog post, I would like to introduce fc-userscan. This little tool scans (home) directories recursively for Nix store references and registers them as per-user roots with the garbage collector. This way, dependencies will be protected even if they cease to be referenced from “official” Nix roots like the current-system profile or a user’s local Nix profile. After registering formerly unmanaged references with fc-userscan, one can fearlessly run updates and garbage collection.
Next week our Autumn 2016 Sprint starts and we really look forward to welcome our guests. We are in the midst of preparation and hope the weather plays along. All details around the sprint can be find on Meetup. Interesting topics are on the agenda as: backy, batou, NixOS and more – there is an Etherpad to gather them.
If you want to contribute but can’t make it in person, think about join us remote. Just let us know in advance (send a short message to firstname.lastname@example.org or poke us on twitter @flyingcircusio).
Back in May I introduced you to the development of vulnix, a tool which initially was done to find out whether a system (might) be affected by a security vulnerability. It does this by matching the derivations name with the product and version specified in the cpe language of the so-called CVEs (Common Vulnerabilities and Exposures). In the meantime we introduced the tool to the community at the Berlin NixOS Meetup and got some wonderful input in which directions we might extend the features. We sprinted the next two days to improve the code quality and broaden the feature set.
Our customers at times require Oracle Java for their applications. Our new platform is based on NixOS. As with most Linux distributions, Oracle Java cannot be installed just like that. Oracle’s license prevents redistribution or direct downloading from their servers. NixOS is no exception there.
While manual installation is pretty straightforward on NixOS, ultimately an automated process is what makes operators happy. We use Batou for this.
Reading Why Order Matters: Turing Equivalence in Automated Systems Administration (by Steve Traugott and Lance Brown) 15 years ago has been a career-changing moment for me. In this blog post, I will explore the meaning of some of the points made in this article for today’s data center infrastructures. I will also give a bit of background on what motivated our recent move to NixOS.