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
nixos-unstable 4 days ago 44b02b52ea6 nixos/trunk-combined/tested
nixos-unstable-small 4 days ago 8dd2fb2ffba nixos/unstable-small/tested
nixpkgs-unstable 6 days ago 61c3169a0e1 nixpkgs/trunk/unstable
nixos-18.09 4 days ago 7e88992a8c7 nixos/release-18.09/tested
nixos-18.09-small 4 days ago 7e88992a8c7 nixos/release-18.09-small/tested
nixpkgs-18.09-darwin 4 days ago 7e88992a8c7 nixpkgs/nixpkgs-18.09-darwin/darwin-tested
nixos-18.03 9 days ago b551f89e256 nixos/release-18.03/tested
nixos-18.03-small 10 days ago b551f89e256 nixos/release-18.03-small/tested
nixpkgs-18.03-darwin 5 days ago d3698e03fb7 nixpkgs/nixpkgs-18.03-darwin/darwin-tested
nixos-17.09 95 days ago 14f9ee66e63 nixos/release-17.09/tested
nixos-17.09-small 80 days ago 24a7883c234 nixos/release-17.09-small/tested
nixpkgs-17.09-darwin 80 days ago 24a7883c234 nixpkgs/nixpkgs-17.09-darwin/darwin-tested
nixos-17.03 298 days ago 78e9665b48f nixos/release-17.03/tested
nixos-17.03-small 255 days ago 2c1838ab99b nixos/release-17.03-small/tested
nixos-16.09 574 days ago 25f4906da6 nixos/release-16.09/tested
nixos-16.09-small 574 days ago 25f4906da6 nixos/release-16.09-small/tested
nixos-16.03 627 days ago dda40aa8d1 nixos/release-16.03/tested
nixos-16.03-small 627 days ago dda40aa8d1 nixos/release-16.03-small/tested
nixos-15.09 738 days ago 3727911 nixos/release-15.09/tested
nixos-15.09-small 739 days ago 3727911 nixos/release-15.09-small/tested
nixos-14.12 1176 days ago b373bf9 nixos/release-14.12/tested
nixos-14.12-small 1016 days ago c191689 nixos/release-14.12-small/tested
nixos-14.04 1210 days ago 8a3eea0 nixos/release-14.04/tested
nixos-14.04-small 1210 days ago 8a3eea0 nixos/release-14.04-small/tested
nixos-13.10 1546 days ago 91e952a nixos/release-13.10/tested

API | Made by Georges Dubus, code is on github