92179785b6
What I missed when I began using Nix and NixOS was a clear overview of how packages, channels, Hydra, the master branch and updates to channels relate to each other. I've noticed I am not the only one, given the amount of times these questions pop up. For now I propose to include this in the Nixpkgs manual, since this seems to be the best fit. However, I think it would be good to include this in either a new manual, i.e., a user manual, or an 'official' tutorial.
48 lines
2.8 KiB
Markdown
48 lines
2.8 KiB
Markdown
---
|
||
title: Introduction
|
||
author: Frederik Rietdijk
|
||
date: 2015-11-25
|
||
---
|
||
|
||
# Introduction
|
||
|
||
The Nix Packages collection (Nixpkgs) is a set of over 30,000 packages for the
|
||
[Nix package manager](http://nixos.org/nix/), released under a [permissive MIT/X11 license](https://github.com/NixOS/nixpkgs/blob/master/COPYING).
|
||
Packages are available for several architectures, and can be used with the Nix package manager
|
||
on most GNU/Linux distributions as well as NixOS.
|
||
|
||
This manual describes how to write packages for the Nix Packages collection
|
||
(Nixpkgs). Thus it’s for packagers and developers who want to add packages to
|
||
Nixpkgs. If you like to learn more about the Nix package manager and the Nix
|
||
expression language, then you are kindly referred to the [Nix manual](http://nixos.org/nix/manual/).
|
||
|
||
## Overview of Nixpkgs
|
||
|
||
Nix expressions describe how to build packages from source and are collected in
|
||
the [nixpkgs repository](https://github.com/NixOS/nixpkgs). Also included in the
|
||
collection are Nix expressions for [NixOS modules](http://nixos.org/nixos/manual/index.html#sec-writing-modules). With
|
||
these expressions the Nix package manager can build binary packages.
|
||
|
||
Packages, including the Nix packages collection, are distributed through
|
||
[channels](http://nixos.org/nix/manual/#sec-channels). The collection is
|
||
distributed for users of Nix on non-NixOS distributions through the channel
|
||
`nixpkgs`. Users of NixOS generally use one of the `nixos-*` channels, e.g.
|
||
`nixos-15.09`, which includes all packages and modules for the stable NixOS
|
||
15.09. The channels of the stable NixOS releases are generally only given
|
||
security updates. More up to date packages and modules are available via the
|
||
`nixos-unstable` channel.
|
||
|
||
Both `nixos-unstable` and `nixpkgs` follow the `master` branch of the Nixpkgs
|
||
repository, although both do lag the `master` branch by generally [a couple of days](http://howoldis.herokuapp.com/). Updates to a channel are distributed as
|
||
soon as all tests for that channel pass, e.g. [this table](http://hydra.nixos.org/job/nixpkgs/trunk/unstable#tabs-constituents)
|
||
shows the status of tests for the `nixpkgs` channel.
|
||
|
||
The tests are conducted by a cluster called [Hydra](http://nixos.org/hydra/),
|
||
which also builds binary packages from the Nix expressions in Nixpkgs. As soon
|
||
as a channel is updated, the binaries are made available via a [binary cache](https://cache.nixos.org). Until the channel updates, binaries that have
|
||
already been built, are available via [Hydra's binary cache](https://hydra.nixos.org).
|
||
|
||
The current Nix expressions of the channels are available in the
|
||
[`nixpkgs-channels`](https://github.com/NixOS/nixpkgs-channels) repository,
|
||
which has branches corresponding to the available channels. There is also the
|
||
Nixpkgs Monitor which keeps track of updates and security vulnerabilities.
|