nixpkgs/nixos/modules/tasks/filesystems/zfs.nix
Ricardo M. Correia e9affb4274 nixos: Add system-wide option to set the hostid
The old boot.spl.hostid option was not working correctly due to an
upstream bug.

Instead, now we will create the /etc/hostid file so that all applications
(including the ZFS kernel modules, ZFS user-space applications and other
unrelated programs) pick-up the same system-wide host id. Note that glibc
(and by extension, the `hostid` program) also respect the host id configured in
/etc/hostid, if it exists.

The hostid option is now mandatory when using ZFS because otherwise, ZFS will
require you to force-import your ZFS pools if you want to use them, which is
undesirable because it disables some of the checks that ZFS does to make sure it
is safe to import a ZFS pool.

The /etc/hostid file must also exist when booting the initrd, before the SPL
kernel module is loaded, so that ZFS picks up the hostid correctly.

The complexity in creating the /etc/hostid file is due to having to
write the host ID as a 32-bit binary value, taking into account the
endianness of the machine, while using only shell commands and/or simple
utilities (to avoid exploding the size of the initrd).
2014-11-12 22:31:49 +01:00

343 lines
11 KiB
Nix

{ config, lib, pkgs, utils, ... }:
#
# todo:
# - crontab for scrubs, etc
# - zfs tunables
with utils;
with lib;
let
cfgSpl = config.boot.spl;
cfgZfs = config.boot.zfs;
cfgSnapshots = config.services.zfs.autoSnapshot;
inInitrd = any (fs: fs == "zfs") config.boot.initrd.supportedFilesystems;
inSystem = any (fs: fs == "zfs") config.boot.supportedFilesystems;
enableAutoSnapshots = cfgSnapshots.enable;
enableZfs = inInitrd || inSystem || enableAutoSnapshots;
kernel = config.boot.kernelPackages;
splPkg = if cfgZfs.useGit then kernel.spl_git else kernel.spl;
zfsPkg = if cfgZfs.useGit then kernel.zfs_git else kernel.zfs;
autosnapPkg = pkgs.zfstools.override {
zfs = zfsPkg;
};
zfsAutoSnap = "${autosnapPkg}/bin/zfs-auto-snapshot";
datasetToPool = x: elemAt (splitString "/" x) 0;
fsToPool = fs: datasetToPool fs.device;
zfsFilesystems = filter (x: x.fsType == "zfs") (attrValues config.fileSystems);
isRoot = fs: fs.neededForBoot || elem fs.mountPoint [ "/" "/nix" "/nix/store" "/var" "/var/log" "/var/lib" "/etc" ];
allPools = unique ((map fsToPool zfsFilesystems) ++ cfgZfs.extraPools);
rootPools = unique (map fsToPool (filter isRoot zfsFilesystems));
dataPools = unique (filter (pool: !(elem pool rootPools)) allPools);
in
{
###### interface
options = {
boot.zfs = {
useGit = mkOption {
type = types.bool;
default = false;
example = true;
description = ''
Use the git version of the SPL and ZFS packages.
Note that these are unreleased versions, with less testing, and therefore
may be more unstable.
'';
};
extraPools = mkOption {
type = types.listOf types.str;
default = [];
example = [ "tank" "data" ];
description = ''
Name or GUID of extra ZFS pools that you wish to import during boot.
Usually this is not necessary. Instead, you should set the mountpoint property
of ZFS filesystems to <literal>legacy</literal> and add the ZFS filesystems to
NixOS's <option>fileSystems</option> option, which makes NixOS automatically
import the associated pool.
However, in some cases (e.g. if you have many filesystems) it may be preferable
to exclusively use ZFS commands to manage filesystems. If so, since NixOS/systemd
will not be managing those filesystems, you will need to specify the ZFS pool here
so that NixOS automatically imports it on every boot.
'';
};
forceImportRoot = mkOption {
type = types.bool;
default = true;
example = false;
description = ''
Forcibly import the ZFS root pool(s) during early boot.
This is enabled by default for backwards compatibility purposes, but it is highly
recommended to disable this option, as it bypasses some of the safeguards ZFS uses
to protect your ZFS pools.
If you set this option to <literal>false</literal> and NixOS subsequently fails to
boot because it cannot import the root pool, you should boot with the
<literal>zfs_force=1</literal> option as a kernel parameter (e.g. by manually
editing the kernel params in grub during boot). You should only need to do this
once.
'';
};
forceImportAll = mkOption {
type = types.bool;
default = true;
example = false;
description = ''
Forcibly import all ZFS pool(s).
This is enabled by default for backwards compatibility purposes, but it is highly
recommended to disable this option, as it bypasses some of the safeguards ZFS uses
to protect your ZFS pools.
If you set this option to <literal>false</literal> and NixOS subsequently fails to
import your non-root ZFS pool(s), you should manually import each pool with
"zpool import -f &lt;pool-name&gt;", and then reboot. You should only need to do
this once.
'';
};
};
services.zfs.autoSnapshot = {
enable = mkOption {
default = false;
type = types.bool;
description = ''
Enable the (OpenSolaris-compatible) ZFS auto-snapshotting service.
Note that you must set the <literal>com.sun:auto-snapshot</literal>
property to <literal>true</literal> on all datasets which you wish
to auto-snapshot.
You can override a child dataset to use, or not use auto-snapshotting
by setting its flag with the given interval:
<literal>zfs set com.sun:auto-snapshot:weekly=false DATASET</literal>
'';
};
frequent = mkOption {
default = 4;
type = types.int;
description = ''
Number of frequent (15-minute) auto-snapshots that you wish to keep.
'';
};
hourly = mkOption {
default = 24;
type = types.int;
description = ''
Number of hourly auto-snapshots that you wish to keep.
'';
};
daily = mkOption {
default = 7;
type = types.int;
description = ''
Number of daily auto-snapshots that you wish to keep.
'';
};
weekly = mkOption {
default = 4;
type = types.int;
description = ''
Number of weekly auto-snapshots that you wish to keep.
'';
};
monthly = mkOption {
default = 12;
type = types.int;
description = ''
Number of monthly auto-snapshots that you wish to keep.
'';
};
};
};
###### implementation
config = mkMerge [
(mkIf enableZfs {
assertions = [
{
assertion = config.networking.hostId != null;
message = "ZFS requires config.networking.hostId to be set";
}
{
assertion = !cfgZfs.forceImportAll || cfgZfs.forceImportRoot;
message = "If you enable boot.zfs.forceImportAll, you must also enable boot.zfs.forceImportRoot";
}
];
boot = {
kernelModules = [ "spl" "zfs" ] ;
extraModulePackages = [ splPkg zfsPkg ];
};
boot.initrd = mkIf inInitrd {
kernelModules = [ "spl" "zfs" ];
extraUtilsCommands =
''
cp -v ${zfsPkg}/sbin/zfs $out/bin
cp -v ${zfsPkg}/sbin/zdb $out/bin
cp -v ${zfsPkg}/sbin/zpool $out/bin
cp -pdv ${zfsPkg}/lib/lib*.so* $out/lib
cp -pdv ${pkgs.zlib}/lib/lib*.so* $out/lib
'';
postDeviceCommands = concatStringsSep "\n" ([''
ZFS_FORCE="${optionalString cfgZfs.forceImportRoot "-f"}"
for o in $(cat /proc/cmdline); do
case $o in
zfs_force|zfs_force=1)
ZFS_FORCE="-f"
;;
esac
done
''] ++ (map (pool: ''
echo "importing root ZFS pool \"${pool}\"..."
zpool import -N $ZFS_FORCE "${pool}"
'') rootPools));
};
boot.loader.grub = mkIf inInitrd {
zfsSupport = true;
};
environment.etc."zfs/zed.d".source = "${zfsPkg}/etc/zfs/zed.d/*";
system.fsPackages = [ zfsPkg ]; # XXX: needed? zfs doesn't have (need) a fsck
environment.systemPackages = [ zfsPkg ];
services.udev.packages = [ zfsPkg ]; # to hook zvol naming, etc.
systemd.packages = [ zfsPkg ];
systemd.services = let
getPoolFilesystems = pool:
filter (x: x.fsType == "zfs" && (fsToPool x) == pool) (attrValues config.fileSystems);
getPoolMounts = pool:
let
mountPoint = fs: escapeSystemdPath fs.mountPoint;
in
map (x: "${mountPoint x}.mount") (getPoolFilesystems pool);
createImportService = pool:
nameValuePair "zfs-import-${pool}" {
description = "Import ZFS pool \"${pool}\"";
requires = [ "systemd-udev-settle.service" ];
after = [ "systemd-udev-settle.service" "systemd-modules-load.service" ];
wantedBy = (getPoolMounts pool) ++ [ "local-fs.target" ];
before = (getPoolMounts pool) ++ [ "local-fs.target" ];
unitConfig = {
DefaultDependencies = "no";
};
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
};
script = ''
zpool_cmd="${zfsPkg}/sbin/zpool"
("$zpool_cmd" list "${pool}" >/dev/null) || "$zpool_cmd" import -N ${optionalString cfgZfs.forceImportAll "-f"} "${pool}"
'';
};
in listToAttrs (map createImportService dataPools) // {
"zfs-mount" = { after = [ "systemd-modules-load.service" ]; };
"zfs-share" = { after = [ "systemd-modules-load.service" ]; };
"zed" = { after = [ "systemd-modules-load.service" ]; };
};
systemd.targets."zfs-import" =
let
services = map (pool: "zfs-import-${pool}.service") dataPools;
in
{
requires = services;
after = services;
};
systemd.targets."zfs".wantedBy = [ "multi-user.target" ];
})
(mkIf enableAutoSnapshots {
systemd.services."zfs-snapshot-frequent" = {
description = "ZFS auto-snapshotting every 15 mins";
after = [ "zfs-import.target" ];
serviceConfig = {
Type = "oneshot";
ExecStart = "${zfsAutoSnap} frequent ${toString cfgSnapshots.frequent}";
};
restartIfChanged = false;
startAt = "*:15,30,45";
};
systemd.services."zfs-snapshot-hourly" = {
description = "ZFS auto-snapshotting every hour";
after = [ "zfs-import.target" ];
serviceConfig = {
Type = "oneshot";
ExecStart = "${zfsAutoSnap} hourly ${toString cfgSnapshots.hourly}";
};
restartIfChanged = false;
startAt = "hourly";
};
systemd.services."zfs-snapshot-daily" = {
description = "ZFS auto-snapshotting every day";
after = [ "zfs-import.target" ];
serviceConfig = {
Type = "oneshot";
ExecStart = "${zfsAutoSnap} daily ${toString cfgSnapshots.daily}";
};
restartIfChanged = false;
startAt = "daily";
};
systemd.services."zfs-snapshot-weekly" = {
description = "ZFS auto-snapshotting every week";
after = [ "zfs-import.target" ];
serviceConfig = {
Type = "oneshot";
ExecStart = "${zfsAutoSnap} weekly ${toString cfgSnapshots.weekly}";
};
restartIfChanged = false;
startAt = "weekly";
};
systemd.services."zfs-snapshot-monthly" = {
description = "ZFS auto-snapshotting every month";
after = [ "zfs-import.target" ];
serviceConfig = {
Type = "oneshot";
ExecStart = "${zfsAutoSnap} monthly ${toString cfgSnapshots.monthly}";
};
restartIfChanged = false;
startAt = "monthly";
};
})
];
}