nixos-config/modules/environment/impermanence.nix

113 lines
3.3 KiB
Nix

{
impermanence,
config,
lib,
pkgs,
inTester,
...
}:
with lib; {
imports = [
"${impermanence}/nixos.nix"
./user-impermanence.nix
];
options = {
environment.impermanence.enable = mkEnableOption "Enables impermanence";
};
config = mkMerge [
{
environment.impermanence.enable = mkDefault (!config.boot.isContainer && !inTester);
}
(mkIf config.environment.impermanence.enable {
boot.initrd.systemd.services.rootfs-cleanup = {
description = "Clean file system root";
wantedBy = [
"initrd.target"
];
after = [
"initrd-root-device.target"
];
before = [
"sysroot.mount"
];
unitConfig.DefaultDependencies = "no";
serviceConfig.Type = "oneshot";
script = ''
# workaround for machines without working rtc battery
# The time may not yet be correctly set, so wait until it is
if [[ $(date '+%s') -lt 1730469314 ]]; then
sleep 30 # this should hopefully be enough
fi
mkdir /btrfs_tmp
mount ${config.fileSystems."/".device} -t btrfs /btrfs_tmp
if [[ -e /btrfs_tmp/root ]]; then
mkdir -p /btrfs_tmp/old_roots
timestamp=$(date --date="@$(stat -c %X /btrfs_tmp/root)" "+%Y-%m-%d_%H:%M:%S")
mv /btrfs_tmp/root "/btrfs_tmp/old_roots/$timestamp"
fi
delete_subvolume_recursively() {
IFS=$'\n'
for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
delete_subvolume_recursively "/btrfs_tmp/$i"
done
btrfs subvolume delete "$1"
}
for i in $(find /btrfs_tmp/old_roots/ -maxdepth 1 -mtime +30); do
delete_subvolume_recursively "$i"
done
btrfs subvolume create /btrfs_tmp/root
umount /btrfs_tmp
'';
};
assertions = [
{
assertion = hasAttr "/" config.fileSystems;
message = "To use impermanence, you need to define a root volume";
}
{
assertion =
if hasAttr "/" config.fileSystems
then config.fileSystems."/".fsType == "btrfs"
else false;
message = "rootfs must be btrfs";
}
{
assertion =
if hasAttr "/" config.fileSystems
then any (t: t == "subvol=root" || t == "subvol=/root") config.fileSystems."/".options
else false;
message = "rootfs must mount subvolume root";
}
];
fileSystems."/persistent" = {
device =
if hasAttr "/" config.fileSystems
then mkDefault config.fileSystems."/".device
else "/dev/null";
fsType = "btrfs";
options = ["subvol=persistent"];
neededForBoot = true;
};
environment.persistence."/persistent" = {
enable = true;
hideMounts = true;
directories = [
"/var/log"
"/var/lib/nixos"
];
files = [
"/etc/ssh/ssh_host_ecdsa_key"
"/etc/ssh/ssh_host_ecdsa_key.pub"
"/etc/ssh/ssh_host_ed25519_key"
"/etc/ssh/ssh_host_ed25519_key.pub"
"/etc/ssh/ssh_host_rsa_key"
"/etc/ssh/ssh_host_rsa_key.pub"
];
};
})
];
}