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{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.services.lvm-snapshots;
snapshotMount = name: "${cfg.mountPoint}/${if isNull cfg.snapshots."${name}".mountName then name else cfg.snapshots."${name}".mountName}";
snapshotName = name: "${name}-snapshot";
snapshotConfig = {
options = {
LV = mkOption {
type = types.str;
};
VG = mkOption {
type = types.str;
};
mountName = mkOption {
type = types.nullOr types.str;
default = null;
};
cowSize = mkOption {
type = types.str;
default = "-l20%%ORIGIN";
description = "Literate argument to lvcreate, escape for systemd";
};
readOnly = mkOption {
type = types.bool;
default = true;
};
persist = mkOption {
type = types.bool;
default = false;
};
};
};
in {
options = {
services.lvm-snapshots = {
snapshots = mkOption {
type = types.attrsOf (types.submodule snapshotConfig);
default = {};
};
mountPoint = mkOption {
type = types.path;
default = "/mnt";
};
};
};
config = mkIf (cfg != {}) {
boot.kernelModules = [ "dm_snapshot" ];
system.activationScripts = mapAttrs' (name: scfg: nameValuePair ("lvm-mountpoint" + name) ''
mkdir -p ${snapshotMount name}
'') cfg.snapshots;
systemd.services = mapAttrs' (name: scfg: nameValuePair ("lvm-snapshot@" + snapshotName name) {
enable = true;
unitConfig = {
StopWhenUnneeded = true;
};
serviceConfig = with pkgs; {
Type = "oneshot";
ExecStart = "${devicemapper}/bin/lvcreate -s ${scfg.cowSize} --name ${snapshotName name} ${scfg.VG}/${scfg.LV}";
ExecStopPre = "${devicemapper}/bin/lvchange -a n ${scfg.VG}/${snapshotName name}";
ExecStop = "${devicemapper}/bin/lvremove ${scfg.VG}/${snapshotName name}";
RemainAfterExit = true;
};
}) cfg.snapshots;
systemd.mounts = mapAttrsToList (name: scfg: {
enable = true;
unitConfig = {
AssertPathIsDirectory = snapshotMount name;
StopWhenUnneeded = !scfg.persist;
};
bindsTo = [ ("lvm-snapshot@" + snapshotName name + ".service") ];
after = [ ("lvm-snapshot@" + snapshotName name + ".service") ];
options = mkIf scfg.readOnly "ro";
where = snapshotMount name;
what = "/dev/" + scfg.VG + "/" + snapshotName name;
}) cfg.snapshots;
};
}
|
