116 lines
2.7 KiB
Nix
116 lines
2.7 KiB
Nix
{ pkgs, ... }:
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let
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btrfs-progs = pkgs.btrfs-progs;
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btrfs = "${btrfs-progs}/bin/btrfs";
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btrfsDevice = "/dev/mapper/prophecy-root-decrypted";
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btrfsOpts = [
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"compress=zstd:2"
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"datacow"
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"datasum"
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"discard=async"
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"ssd_spread"
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"noatime"
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"fatal_errors=panic"
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];
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in
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{
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fileSystems."/" = {
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device = btrfsDevice;
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fsType = "btrfs";
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options = [ "subvol=root" ] ++ btrfsOpts;
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};
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systemd.tmpfiles.settings."10-vacu"."/btr-root-in-here".d = {
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mode = "0700";
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user = "root";
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group = "root";
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};
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fileSystems."/btr-root-in-here/btr-root" = {
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device = btrfsDevice;
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fsType = "btrfs";
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options = [ "ro" ] ++ btrfsOpts;
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};
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boot.initrd.systemd.services."vacu-impermanence-setup" = {
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enable = true;
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wantedBy = [ "initrd-root-device.target" ];
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before = [
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"sysroot.mount"
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"create-needed-for-boot-dirs.service"
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];
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serviceConfig.Type = "oneshot";
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script = ''
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set -euo pipefail
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btrfs_tmp="$(mktemp -d)"
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mount ${btrfsDevice} "$btrfs_tmp"
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(
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cd "$btrfs_tmp"
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if [[ -e root ]]; then
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mkdir -p old_roots
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timestamp=$(date --date="@$(stat -c %Y root)" "+%Y-%m-%d_%H:%M:%S")
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mv root "old_roots/$timestamp"
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fi
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btrfs subvolume create ./root
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btrfs subvolume delete ./big-tmp
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btrfs subvolume create ./big-tmp
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)
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umount "$btrfs_tmp"
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rmdir "$btrfs_tmp"
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'';
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};
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vacu.packages = [
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btrfs-progs
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(pkgs.writeScriptBin "delete_old_root" ''
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set -euo pipefail
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timestamp="$1"
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shift
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if [[ -z "$timestamp" ]]; then
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echo "missing arg" >&2
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exit 1
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fi
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mntpoint="$(mktemp -d)"
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mount -t btrfs ${btrfsDevice} "$mntpoint"
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full_path="$mntpoint/old_roots/$timestamp"
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if ! [[ -d "$full_path" ]]; then
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echo "couldnt find subvol old_roots/$timestamp" >&2
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exit 1
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fi
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${btrfs} subvolume delete -R "$full_path"
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'')
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];
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# back me up, scotty
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fileSystems."/persistent" = {
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device = btrfsDevice;
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neededForBoot = true;
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fsType = "btrfs";
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options = [ "subvol=persistent" ] ++ btrfsOpts;
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};
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# keep me around, but no need to back me up
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fileSystems."/persistent-cache" = {
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device = btrfsDevice;
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neededForBoot = true;
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fsType = "btrfs";
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options = [ "subvol=persistent-cache" ] ++ btrfsOpts;
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};
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# deleted and re-created on every boot, for stuff too big to go in a tmpfs
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fileSystems."/tmp" = {
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device = btrfsDevice;
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fsType = "btrfs";
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options = [ "subvol=big-tmp" ] ++ btrfsOpts;
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};
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fileSystems."/nix" = {
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device = btrfsDevice;
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fsType = "btrfs";
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options = [ "subvol=nix" ] ++ btrfsOpts;
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};
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}
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