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{
pov,
povSelf,
hostConfig,
config,
lib,
pkgs,
...
}:
let
inherit (lib) types;
cfgFilesystem = lib.getAttrFromPath pov config;
cfg = lib.getAttrFromPath povSelf config;
perms = {
user = lib.mkOption {
type = with types; nullOr str;
default = null;
};
group = lib.mkOption {
type = with types; nullOr str;
default = null;
};
mode = lib.mkOption {
type = with types; nullOr str;
default = null;
};
};
in
{
options = {
home.enable = {
type = types.bool;
default = false;
};
system = {
enable = {
type = types.bool;
default = false;
};
dirs = {
default = [ ];
type =
with types;
listOf (oneOf [
str
(submodule {
options = {
directory = lib.mkOption { type = types.str; };
} // perms;
})
]);
};
files = {
default = [ ];
type =
with types;
listOf (oneOf [
str
(submodule {
options = {
file = lib.mkOption { type = types.str; };
parentDirectory = lib.mkOption {
type = with types; nullOr (submodule perms);
default = null;
};
} // perms;
})
]);
};
};
};
config = lib.mkMerge [
(lib.mkIf cfg.home.enable {
assertions = [
{
assertion = config.modules.filesystem.rootDisk.type == "zfs";
message = ''
Impermanence is currently only available for ZFS.
'';
}
];
modules.filesystem.rootDisk.parts.home = true;
})
(lib.mkIf cfg.system.enable {
assertions = [
{
assertion = config.modules.filesystem.rootDisk.type == "zfs";
message = ''
Impermanence is currently only available for ZFS.
'';
}
];
modules.filesystem.rootDisk.parts.system = true;
boot.initrd.systemd.services = {
defenestrate = {
description = "Defenestrate old root";
wantedBy = [ "initrd.target" ];
after = [ "zfs-import.target" ];
before = [ "sysroot.mount" ];
onFailure = [ "emergency.target" ];
unitConfig.DefaultDependencies = "no";
serviceConfig.Type = "oneshot";
script =
let
prefix = "${hostConfig.hostName}/os/nixos/root-";
in
''
# We keep root from the previous last 3 boots
# Any command except create can fail in case the system has not
# booted that often yet
zfs destroy -r ${prefix}4 || true
zfs rename ${prefix}3 ${prefix}4 || true
zfs rename ${prefix}2 ${prefix}3 || true
zfs rename ${prefix}1 ${prefix}2 || true
zfs create -o devices=off -o exec=off -o mountpoint=legacy -o setuid=off ${prefix}1
'';
};
};
environment.persistence."/nix/persist/system" = {
enable = true;
hideMounts = true;
directories = [
"/etc/zfs"
"/var/log"
"/var/lib/nixos"
"/var/lib/systemd/coredump"
] ++ cfg.system.dirs;
files = [
"/etc/machine-id"
] ++ cfg.system.files;
};
#zaphyra: hack to persist `/var/lib/private/<service>` (see https://github.com/nix-community/impermanence/issues/213)
system.activationScripts = {
"createPersistentStorageDirs".deps = [
"var-lib-private-permissions"
"users"
"groups"
];
"var-lib-private-permissions" = {
deps = [ "specialfs" ];
text = ''
mkdir -p /nix/persist/system/var/lib/private
chmod 0700 /nix/persist/system/var/lib/private
'';
};
};
})
];
}