How does channel update?

Anyone with commit access can push changes to either master or one of the release-XX.XX branches.

Each channel has an associated jobset on Hydra (Nix CI) that is a collection of individual jobs. A job roughly corresponds to building a particular package, which itself may depend on other packages built by other jobs.

Before a channel can update, its associated jobset must be finished building, though the building of some jobs may fail.

As long as certain special jobs -- unstable for nixpkgs, and tested for nixos -- build successfully, the channel can update. The role of these special jobs is to ensure that essential functionality is present on each channel update.

There are two major differences between those jobsets:

  • nixpkgs-unstable
    • builds all packages for supported platforms (Linux, Darwin)
    • unstable job that consists of most commonly used packages
  • nixos-*
    • builds all packages and NixOS machinery only for Linux
    • tested job that consists of mostly NixOS tests firing up qemu instances with different kinds of configurations

For a channel to be updated two conditions need to be satisfied:

  • Particular jobset evaluation needs to be completely built ie. no more queued jobs, even if some jobs may fail
  • Particular jobset evaluation's tested/unstable job needs to be built succesfully

The nixos.org server has a cronjob for which nixos-channel-scripts are executed and poll for the newest jobset that satisfies the above two conditions and trigger a channel update.

Once triggered, release files such as ISOs are copied. For the NixOS channel command-not-found index is generated, which can take some time since it has to fetch all packages.

nixpkgs is quickly updated since none of the above needs to happen once a channel update is triggered.

Channel Last updated Commit Hydra job for tests
nixpkgs-unstable 1 day ago 1d78df2729 nixpkgs/trunk/unstable
nixos-unstable-small 8 days ago 387256c0f2 nixos/unstable-small/tested
nixos-unstable 16 days ago 01c3847b9c nixos/trunk-combined/tested
nixos-17.03-small 18 hours ago b3fa6295ad nixos/release-17.03-small/tested
nixos-17.03 2 days ago 4d1e1d07f9 nixos/release-17.03/tested
nixos-16.09-small 58 days ago 25f4906da6 nixos/release-16.09-small/tested
nixos-16.09 58 days ago 25f4906da6 nixos/release-16.09/tested
nixos-16.03-small 111 days ago dda40aa8d1 nixos/release-16.03-small/tested
nixos-16.03 111 days ago dda40aa8d1 nixos/release-16.03/tested
nixos-15.09-small 222 days ago 3727911 nixos/release-15.09-small/tested
nixos-15.09 221 days ago 3727911 nixos/release-15.09/tested
nixos-14.12-small 499 days ago c191689 nixos/release-14.12-small/tested
nixos-14.12 659 days ago b373bf9 nixos/release-14.12/tested
nixos-14.04-small 693 days ago 8a3eea0 nixos/release-14.04-small/tested
nixos-14.04 693 days ago 8a3eea0 nixos/release-14.04/tested
nixos-13.10 1029 days ago 91e952a nixos/release-13.10/tested

API | Made by Georges Dubus, code is on github