nixpkgs/nixos/modules/system/etc/etc.nix
Taeer Bar-Yam 0bef0c38f7 lib.modules: add mkDerivedConfig
mkDerivedConfig : Option a -> (a -> Definition b) -> Definition b

Create config definitions with the same priority as the definition of another option.
This should be used for option definitions where one option sets the value of another as a convenience.
For instance a config file could be set with a `text` or `source` option, where text translates to a `source`
value using `mkDerivedConfig options.text (pkgs.writeText "filename.conf")`.

It takes care of setting the right priority using `mkOverride`.
2021-11-15 07:03:41 -05:00

202 lines
5.3 KiB
Nix

# Management of static files in /etc.
{ config, lib, pkgs, ... }:
with lib;
let
etc' = filter (f: f.enable) (attrValues config.environment.etc);
etc = pkgs.runCommandLocal "etc" {
# This is needed for the systemd module
passthru.targets = map (x: x.target) etc';
} /* sh */ ''
set -euo pipefail
makeEtcEntry() {
src="$1"
target="$2"
mode="$3"
user="$4"
group="$5"
if [[ "$src" = *'*'* ]]; then
# If the source name contains '*', perform globbing.
mkdir -p "$out/etc/$target"
for fn in $src; do
ln -s "$fn" "$out/etc/$target/"
done
else
mkdir -p "$out/etc/$(dirname "$target")"
if ! [ -e "$out/etc/$target" ]; then
ln -s "$src" "$out/etc/$target"
else
echo "duplicate entry $target -> $src"
if [ "$(readlink "$out/etc/$target")" != "$src" ]; then
echo "mismatched duplicate entry $(readlink "$out/etc/$target") <-> $src"
ret=1
continue
fi
fi
if [ "$mode" != symlink ]; then
echo "$mode" > "$out/etc/$target.mode"
echo "$user" > "$out/etc/$target.uid"
echo "$group" > "$out/etc/$target.gid"
fi
fi
}
mkdir -p "$out/etc"
${concatMapStringsSep "\n" (etcEntry: escapeShellArgs [
"makeEtcEntry"
# Force local source paths to be added to the store
"${etcEntry.source}"
etcEntry.target
etcEntry.mode
etcEntry.user
etcEntry.group
]) etc'}
'';
in
{
###### interface
options = {
environment.etc = mkOption {
default = {};
example = literalExpression ''
{ example-configuration-file =
{ source = "/nix/store/.../etc/dir/file.conf.example";
mode = "0440";
};
"default/useradd".text = "GROUP=100 ...";
}
'';
description = ''
Set of files that have to be linked in <filename>/etc</filename>.
'';
type = with types; attrsOf (submodule (
{ name, config, options, ... }:
{ options = {
enable = mkOption {
type = types.bool;
default = true;
description = ''
Whether this /etc file should be generated. This
option allows specific /etc files to be disabled.
'';
};
target = mkOption {
type = types.str;
description = ''
Name of symlink (relative to
<filename>/etc</filename>). Defaults to the attribute
name.
'';
};
text = mkOption {
default = null;
type = types.nullOr types.lines;
description = "Text of the file.";
};
source = mkOption {
type = types.path;
description = "Path of the source file.";
};
mode = mkOption {
type = types.str;
default = "symlink";
example = "0600";
description = ''
If set to something else than <literal>symlink</literal>,
the file is copied instead of symlinked, with the given
file mode.
'';
};
uid = mkOption {
default = 0;
type = types.int;
description = ''
UID of created file. Only takes effect when the file is
copied (that is, the mode is not 'symlink').
'';
};
gid = mkOption {
default = 0;
type = types.int;
description = ''
GID of created file. Only takes effect when the file is
copied (that is, the mode is not 'symlink').
'';
};
user = mkOption {
default = "+${toString config.uid}";
type = types.str;
description = ''
User name of created file.
Only takes effect when the file is copied (that is, the mode is not 'symlink').
Changing this option takes precedence over <literal>uid</literal>.
'';
};
group = mkOption {
default = "+${toString config.gid}";
type = types.str;
description = ''
Group name of created file.
Only takes effect when the file is copied (that is, the mode is not 'symlink').
Changing this option takes precedence over <literal>gid</literal>.
'';
};
};
config = {
target = mkDefault name;
source = mkIf (config.text != null) (
let name' = "etc-" + baseNameOf name;
in mkDerivedConfig options.text (pkgs.writeText name')
);
};
}));
};
};
###### implementation
config = {
system.build.etc = etc;
system.activationScripts.etc = stringAfter [ "users" "groups" ]
''
# Set up the statically computed bits of /etc.
echo "setting up /etc..."
${pkgs.perl.withPackages (p: [ p.FileSlurp ])}/bin/perl ${./setup-etc.pl} ${etc}/etc
'';
};
}