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nixpkgs/nixos/modules/misc/version.nix
Jan Malakhovski 119c8f91e7 nixos: introduce system.nixosLabel option and use it where appropriate
Setting nixosVersion to something custom is useful for meaningful GRUB
menus and /nix/store paths, but actuallly changing it rebulids the
whole system path (because of `nixos-version` script and manual
pages). Also, changing it is not a particularly good idea because you
can then be differentitated from other NixOS users by a lot of
programs that read /etc/os-release.

This patch introduces an alternative option that does all you want
from nixosVersion, but rebuilds only the very top system level and
/etc while using your label in the names of system /nix/store paths,
GRUB and other boot loaders' menus, getty greetings and so on.
2016-01-08 22:26:15 +00:00

126 lines
3.6 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.system;
releaseFile = "${toString pkgs.path}/.version";
suffixFile = "${toString pkgs.path}/.version-suffix";
revisionFile = "${toString pkgs.path}/.git-revision";
in
{
options.system = {
stateVersion = mkOption {
type = types.str;
default = cfg.nixosRelease;
description = ''
Every once in a while, a new NixOS release may change
configuration defaults in a way incompatible with stateful
data. For instance, if the default version of PostgreSQL
changes, the new version will probably be unable to read your
existing databases. To prevent such breakage, you can set the
value of this option to the NixOS release with which you want
to be compatible. The effect is that NixOS will option
defaults corresponding to the specified release (such as using
an older version of PostgreSQL).
'';
};
nixosLabel = mkOption {
type = types.str;
description = ''
NixOS version name to be used in the names of generated
outputs and boot labels.
If you ever wanted to influence the labels in your GRUB menu,
this is option is for you.
Can be set directly or with <envar>NIXOS_LABEL</envar>
environment variable for <command>nixos-rebuild</command>,
e.g.:
<screen>
#!/bin/sh
today=`date +%Y%m%d`
branch=`(cd nixpkgs ; git branch 2>/dev/null | sed -n '/^\* / { s|^\* ||; p; }')`
revision=`(cd nixpkgs ; git rev-parse HEAD)`
export NIXOS_LABEL="$today.$branch-''${revision:0:7}"
nixos-rebuild switch</screen>
'';
};
nixosVersion = mkOption {
internal = true;
type = types.str;
description = "NixOS version.";
};
nixosRelease = mkOption {
readOnly = true;
type = types.str;
default = readFile releaseFile;
description = "NixOS release.";
};
nixosVersionSuffix = mkOption {
internal = true;
type = types.str;
default = if pathExists suffixFile then readFile suffixFile else "pre-git";
description = "NixOS version suffix.";
};
nixosRevision = mkOption {
internal = true;
type = types.str;
default = if pathExists revisionFile then readFile revisionFile else "master";
description = "NixOS Git revision hash.";
};
nixosCodeName = mkOption {
readOnly = true;
type = types.str;
description = "NixOS release code name.";
};
defaultChannel = mkOption {
internal = true;
type = types.str;
default = https://nixos.org/channels/nixos-unstable;
description = "Default NixOS channel to which the root user is subscribed.";
};
};
config = {
system = {
# These defaults are set here rather than up there so that
# changing them would not rebuild the manual
nixosLabel = mkDefault (maybeEnv "NIXOS_LABEL" cfg.nixosVersion);
nixosVersion = mkDefault (maybeEnv "NIXOS_VERSION" (cfg.nixosRelease + cfg.nixosVersionSuffix));
# Note: code names must only increase in alphabetical order.
nixosCodeName = "Emu";
};
# Generate /etc/os-release. See
# http://0pointer.de/public/systemd-man/os-release.html for the
# format.
environment.etc."os-release".text =
''
NAME=NixOS
ID=nixos
VERSION="${config.system.nixosVersion} (${config.system.nixosCodeName})"
VERSION_ID="${config.system.nixosVersion}"
PRETTY_NAME="NixOS ${config.system.nixosVersion} (${config.system.nixosCodeName})"
HOME_URL="http://nixos.org/"
'';
};
}