(wip) Setup btrfs impermanence

This commit is contained in:
Madeleine Sydney
2024-12-28 20:29:43 -07:00
parent 6240431d36
commit 9a99a6dfb7
4 changed files with 140 additions and 50 deletions

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@@ -6,6 +6,7 @@
];
sydnix = {
filesystemType = "btrfs";
impermanence = {
enable = false;
directories = [
@@ -13,10 +14,12 @@
# This means all users/groups without specified uids/gids will have them
# reassigned on reboot."
"/var/lib/nixos"
# We don't want to have different ssh keys on reboot, because ssh keys
# are expected to consistently identify machines... I think. I mostly
# just think it's annoying to edit ~/.ssh/known_hosts all the time.
"/etc/ssh"
];
rollbackTo = "blank";
dataset = "rpool/local/home";
device = "placeholderrrr";
archiveLimit = 3;
};
users.users = [

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@@ -0,0 +1,13 @@
{ config, lib, pkgs, ... }:
with lib;
{
options = {
sydnix.filesystemType = mkOption {
type = types.nullOr (types.enum [ "btrfs" ]);
description = "The name of the filesystem to be used.";
default = null;
};
};
}

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@@ -32,30 +32,29 @@ in {
default = [];
};
rollbackTo = mkOption {
type = types.str;
};
archiveTo = mkOption {
type = types.str;
default = "/persist/previous/home";
};
dataset = mkOption {
device = mkOption {
description = "Device to be wiped";
type = types.str;
};
archiveLimit = mkOption {
type = types.ints.positive;
description = "The number of previous roots to preserve.";
default = 3;
};
};
};
config = mkIf cfg.enable {
# Create a group called `cfg.persistGroupName`
users.groups.${cfg.persistGroupName} = {
name = cfg.persistGroupName;
};
systemd.tmpfiles.settings = {
"10-persist" = {
# Permit members of `cfg.persistGroupName` to read, write, and execute
# /persist.
"/persist" = {
z = {
group = cfg.persistGroupName;
@@ -65,68 +64,100 @@ in {
};
};
boot.initrd.systemd.initrdBin = with pkgs; [
zfs
];
# TODO: Move this somewhere else.
programs.fuse.userAllowOther = true;
# sudo mount -o ro -t virtiofs mount-dots /persist/dots
boot.initrd.systemd = {
# `pkgs.babashka` calls `pkgs.babashka-unwrapped`, and will explode if it
# cannot find it.
storePaths = [ pkgs.babashka-unwrapped ];
initrdBin = with pkgs; [
babashka
util-linux
];
};
boot.initrd.systemd.services.erase-darlings =
let service = {
description = "Rollback filesystem to a blank state on boot";
wantedBy = [
"initrd.target"
];
after = [
# "zfs-import.service"
"zfs-import-rpool.service"
];
before = [
"sysroot.mount"
];
path = [ pkgs.zfs ];
path = with pkgs; [ util-linux babashka ];
unitConfig.DefaultDependencies = "no";
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
};
script = /* bash */ ''
zfs rollback -r rpool/local/root@blank \
&& echo ">> >> rollback complete << <<"
'';
script =
let bb-script = "/sysroot" + ./impermanence/erase-darlings.clj;
in ''${pkgs.babashka}/bin/bb "${bb-script}" -n "${toString cfg.archiveLimit}" --device "${cfg.device}"'';
};
in if config.boot.initrd.systemd.enable
then service
else throw "sydnix.impermanence currently requires config.boot.initrd.systemd.enable'!";
systemd.services =
let erase-home-darlings = {
description = "Rollback home to a blank state on boot";
wantedBy = [
"local-fs-pre.target"
"zfs-mount.service"
];
before = [
"local-fs.target"
"local-fs-pre.target"
"zfs-mount.service"
];
path = [ pkgs.zfs pkgs.babashka pkgs.util-linux ];
unitConfig.DefaultDependencies = "no";
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
ExecStart =
let script = ./erase-home-darlings.clj;
in ''${pkgs.babashka}/bin/bb "${script}" -n "${toString cfg.archiveLimit}" --dataset "${cfg.dataset}" --rollback-to "${cfg.rollbackTo}"'';
};
stopIfChanged = false;
restartIfChanged = false;
};
in {
# inherit erase-home-darlings;
};
# TODO: Remove this.
# boot.initrd.systemd.services.erase-darlings-old =
# let service = {
# description = "Rollback filesystem to a blank state on boot";
# wantedBy = [
# "initrd.target"
# ];
# after = [
# # "zfs-import.service"
# "zfs-import-rpool.service"
# ];
# before = [
# "sysroot.mount"
# ];
# path = [ pkgs.zfs ];
# unitConfig.DefaultDependencies = "no";
# serviceConfig = {
# Type = "oneshot";
# RemainAfterExit = true;
# };
# script = /* bash */ ''
# zfs rollback -r rpool/local/root@blank \
# && echo ">> >> rollback complete << <<"
# '';
# };
# in if config.boot.initrd.systemd.enable
# then service
# else throw "sydnix.impermanence currently requires config.boot.initrd.systemd.enable'!";
# systemd.services =
# let erase-home-darlings = {
# description = "Rollback home to a blank state on boot";
# wantedBy = [
# "local-fs-pre.target"
# "zfs-mount.service"
# ];
# before = [
# "local-fs.target"
# "local-fs-pre.target"
# "zfs-mount.service"
# ];
# path = [ pkgs.zfs pkgs.babashka pkgs.util-linux ];
# unitConfig.DefaultDependencies = "no";
# serviceConfig = {
# Type = "oneshot";
# RemainAfterExit = true;
# ExecStart =
# let script = ./erase-home-darlings.clj;
# in ''${pkgs.babashka}/bin/bb "${script}" -n "${toString cfg.archiveLimit}" --dataset "${cfg.dataset}" --rollback-to "${cfg.rollbackTo}"'';
# };
# stopIfChanged = false;
# restartIfChanged = false;
# };
# in {
# # inherit erase-home-darlings;
# };
environment.persistence."/persist/root" = {
directories = cfg.directories;

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@@ -0,0 +1,43 @@
#!/usr/bin/env bb
(require '[clojure.core.match :refer [match]]
'[babashka.cli :as cli]
'[clojure.pprint :as pp]
'[clojure.tools.logging :as l]
'[babashka.process :refer [shell check process] :as p])
(def cli-spec
{:spec
{:archive-limit {:coerce :int
:alias :n
:validate #(pos? %)
:default 3
:desc "Number of archives to save at a time."}
:device {:coerce :string
;; :validate fs/exists?
:require true
:desc "Dataset to be archived and rolled back."}
:previous-roots
{:coerce :string
:default "/persist/previous"
:desc "The path under which previous roots will be stored."}
:error-fn
(fn [{:keys [spec type cause msg option] :as data}]
(when (= :org.babashka/cli type)
(case cause
:require
(println
(format "Missing required argument: %s\n" option))))
(System/exit 1))}})
(defmacro with-echoed-shell-commands [& body]
(let [print-cmd #(println (str "+ " (str/join (:cmd %))))]
`(binding [p/*defaults* {:pre-start-fn ~print-cmd}]
~@body)))
(defn -main [opts]
(pp/pprint opts)
(with-echoed-shell-commands
(shell "mount")))
(-main (cli/parse-opts *command-line-args* cli-spec))