nixpkgs/modules/installer/tools/nixos-checkout.nix

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# This module generates the nixos-checkout script, which replaces the
# NixOS and Nixpkgs source trees in /etc/nixos/{nixos,nixpkgs} with
# Subversion checkouts.
{config, pkgs, ...}:
with pkgs.lib;
let
options = {
# !!! These option (and their implementation) seems
# over-engineering. nixos-checkout was never intended to be a
# generic, "check out anything that the user want to have from any
# version management system whatsoever", but merely a trivial
# convenience script to checkout the NixOS and Nixpkgs trees
# during or after a NixOS installation.
installer.repos.nixos = mkOption {
default = [ { type = "svn"; } ];
example =
[ { type = "svn"; url = "https://svn.nixos.org/repos/nix/nixos/branches/stdenv-updates"; target = "/etc/nixos/nixos-stdenv-updates"; }
{ type = "git"; initialize = ''git clone git://mawercer.de/nixos $target''; update = "git pull origin"; target = "/etc/nixos/nixos-git"; }
];
description = ''
The NixOS repository from which the system will be built.
<command>nixos-checkout</command> will update all working
copies of the given repositories,
<command>nixos-rebuild</command> will use the first item
which has the attribute <literal>default = true</literal>
falling back to the first item. The type defines the
repository tool added to the path. It also defines a "valid"
repository. If the target directory already exists and it's
not valid it will be moved to the backup location
<filename><replaceable>dir</replaceable>-date</filename>.
For svn the default target and repositories are
<filename>/etc/nixos/nixos</filename> and
<filename>https://svn.nixos.org/repos/nix/nixos/trunk</filename>.
For git repositories update is called after initialization
when the repo is initialized. The initialize code is run
from working directory dirname
<replaceable>target</replaceable> and should create the
directory
<filename><replaceable>dir</replaceable></filename>. For
the executables used see <option>repoTypes</option>.
'';
};
installer.repos.nixpkgs = mkOption {
default = [ { type = "svn"; } ];
description = "same as <option>repos.nixos</option>";
};
installer.repoTypes = mkOption {
default = {
svn = { valid = "[ -d .svn ]"; env = [ pkgs.coreutils pkgs.subversion ]; };
git = { valid = "[ -d .git ]"; env = [ pkgs.coreutils pkgs.git pkgs.gnused /* FIXME: use full path to sed in nix-pull */ ]; };
};
description = ''
Defines, for each supported version control system
(e.g. <literal>git</literal>), the dependencies for the
mechanism, as well as a test used to determine whether a
directory is a checkout created by that version control
system.
'';
};
};
### implementation
# prepareRepoAttrs adds svn defaults and preparse the repo attribute sets so that they
# returns in any case:
# { type = git/svn;
# target = path;
# initialize = cmd; # must create target dir, dirname target will exist
# update = cmd; # pwd will be target
# default = true/false;
# }
prepareRepoAttrs = repo : attrs :
assert (isAttrs attrs);
assert (repo + "" == repo); # assert repo is a string
if (! (attrs ? type)) then
throw "repo type is missing of : ${showVal attrs}"
# prepare svn repo
else if attrs.type == "svn" then
let a = { # add svn defaults
url = "https://svn.nixos.org/repos/nix/${repo}/trunk";
target = "/etc/nixos/${repo}";
} // attrs; in
rec {
inherit (a) type target;
default = if a ? default then a.default else false;
initialize = "svn co ${a.url} ${a.target}";
update = initialize; # co is just as fine as svn update
}
# prepare git repo
else if attrs.type == "git" then # sanity check for existing attrs
assert (all id (map ( attr : if hasAttr attr attrs then true
else throw "git repository item is missing attribute ${attr}")
[ "target" "initialize" "update" ]
));
let t = escapeShellArg attrs.target; in
rec {
inherit (attrs) type target;
default = if attrs ? default then attrs.default else false;
update = "cd ${t}; ${attrs.update}";
initialize = ''
cd $(dirname ${t}); ${attrs.initialize}
[ -d ${t} ] || { echo "git initialize failed to create target directory ${t}"; exit 1; }
${update}'';
}
else throw "unkown repo type ${attrs.type}";
# apply prepareRepoAttrs on each repo definition
repos = mapAttrs ( repo : list : map (x : (prepareRepoAttrs repo x) // { inherit repo; } ) list ) config.installer.repos;
# function returning the default repo (first one having attribute default or head of list)
defaultRepo = list : head ( (filter ( attrs : attrs ? default && attrs.default == true ) list)
++ list );
# creates the nixos-checkout script
nixosCheckout = pkgs.substituteAll {
name = "nixos-checkout";
dir = "bin";
isExecutable = true;
src = pkgs.writeScript "nixos-checkout" (''
#! @shell@ -e
# this file is automatically generated from nixos configuration file settings (installer.repos)
backupTimestamp=$(date "+%Y%m%d%H%M%S")
'' + concatMapStrings ( attrs :
let repoType = builtins.getAttr attrs.type config.installer.repoTypes;
target = escapeShellArg attrs.target; in
''
# ${attrs.type} repo ${target}
PATH=
for path in ${toString repoType.env}; do
PATH=$PATH:$path/bin:$path/sbin
done
if [ -d ${target} ] && { cd ${target} && { ${ repoType.valid}; }; }; then
echo; echo '>> ' updating ${attrs.type} repo ${target}
set -x; ${attrs.update}; set +x
else # [ make backup and ] initialize
[ -e ${target} ] && mv ${target} ${target}-$backupTimestamp
target=${target}
[ -d "$(dirname ${target})" ] || mkdir -p "$(dirname ${target})"
echo; echo '>> 'initializing ${attrs.type} repo ${target}
set -x; ${attrs.initialize}; set +x
fi
''
) # flatten all repo definition to one list adding the repository
( concatLists (flattenAttrs repos) )
);
};
in
{
require = options;
environment.systemPackages = [nixosCheckout];
}