A coredump is a snapshot of a process’s memory that is usually created by the kernel when a crash happens. These can be fairly helpful to find out which part of the code broke by looking at the backtrace or finding any kind of corruption by introspecting the memory itself. Unfortunately it can be a bit tedious to work with these. This article aims to give an overview over helpful tools & tricks to leverage the full power of coredumps on Nix-based systems.
One of the most important features for system administrators who operate NixOS systems are atomic upgrades which means that a deployment won’t reach an inconsistent state: if building a new system’s configuration succeeds, it will be activated in a single step by replacing the /run/current-system-symlink. If a build fails, e.g. due to broken packages, the configuration won’t be activated. This also means that downgrades are fairly simple since a previous configuration can be reactivated in a so-called rollback by changing the symlink to /run/current-system back to the previous store-path.
This is part 2 of a series of blog posts explaining how we took an existing Windows installation on hardware and moved it into a VM running on top of NixOS. Previously, we discussed how we performed the actual storage migration. In this post, we’ll cover the various performance optimisations we tried, what worked, and what didn’t work. GPU passthrough Since the machine is, amongst other things, used for gaming, graphics performance is critical.
This is part 1 of a series of blog posts explaining how we took an existing Windows installation on hardware and moved it into a VM running on top of NixOS. Background We have a decently-equipped desktop PC sitting in our office, which is designated for data experiments using TensorFlow and such. During off-hours, it’s also used for games, and for that purpose it has Windows installed on it. We decided to try moving Windows into a VM within NixOS so that we could run both operating systems in parallel.
History The NixOS RFC process was established in March 2017, initiated by zimbatm, teh and Moretea in order to standardise a process to find an agreement on larger changes to Nix/NixOS/Nixpkgs and the ecosystem in general. Over the following one and a half years a few uncontroversial RFCs were merged but for most of the RFCs that needed further discussion nobody felt responsible to make a decision. That is the reason RFC 36 was written in collaboration with most core Nix/Nixpkgs members at the last NixCon and merged in December 2018 in order to streamline the process and define clearer responsibilities.
NixOS contains infrastructure for building integration tests based on QEMU/KVM virtual machines running NixOS. Tests built on this infrastructure are continuously run on new nixpkgs versions to ensure that NixOS continues to install and boot and that various services continue to operate correctly. This post illustrates how one may test a simple web service using NixOS tests. To have a simple enough example at hand, we wrote a small service in PHP—a classical guestbook in which visitors can leave a message that will then be written to a database and subsequently shown to later visitors of the same site.
To set up a NixOS system, you usually boot into a live NixOS system and install it onto a local disk as outlined in the manual. You can then modify the system configuration to tailor it to your needs. The build system Hydra builds live images like ISO images, container tarballs or AMIs based on their definition in nixpkgs. These images are made available for download on the official website.
In the past year some Mayflower colleagues have started using and contributing to NixOS, a purely functional GNU/Linux distribution that combines package and configuration management. We decided that we would give it a try in production but stumbled upon some issues that had to be resolved first. We have added new packages, services and fixed up some internal. Due to this work two colleagues have even gained commit access in the process.
I have been following the development of NixOps for some months. NixOps is a cloud deployment tool using nix, the functional package manager for unix systems. Nix makes it very intuitive to define absolute package dependencies. No more thinking and guessing about required runtime dependencies. NixOps supports deploying to different platforms. Bare-metal, cloud, and even virtual environments like virtualbox work out of the box. I have worked in many projects using vagrant.