Polish erase-home-darlings.clj
This commit is contained in:
Madeleine Sydney
25
README.org
25
README.org
@@ -35,14 +35,14 @@
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let modules = list-nix-directory ./modules/nixos;
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in { ... }: {
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imports =
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let x = builtins.map (m: ./modules/nixos/${m}) modules;
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in x;
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builtins.map (m: ./modules/nixos/${m}) modules;
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};
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homeManagerModules.default =
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let modules = list-nix-directory ./modules/home;
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in { ... }: {
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imports = builtins.map (m: ./modules/home/${m}) modules;
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imports =
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builtins.map (m: ./modules/home/${m}) modules;
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};
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nixosConfigurations = (
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@@ -51,7 +51,19 @@
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homeConfigurations =
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let users = builtins.readDir ./users;
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mkUser = username: _v: import ./users/${username}/default.nix;
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mkUser = username: _v: {
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imports = [
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(import ./users/${username}).home
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inputs.self.homeManagerModules.default
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({ lib, ... }: {
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home.username = username;
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})
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inputs.impermanence.homeManagerModules.impermanence
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];
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};
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in
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builtins.mapAttrs mkUser users;
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};
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@@ -87,6 +99,8 @@ let mkHost = k: v: nixpkgs.lib.nixosSystem {
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lib.filterAttrs
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(k: _v: builtins.elem k config.sydnix.users.users)
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self.homeConfigurations;
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home-manager.extraSpecialArgs = inputs // { inherit self; };
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})
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];
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};
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@@ -113,6 +127,9 @@ builtins.mapAttrs mkHost (builtins.readDir ./hosts)
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# reassigned on reboot.
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"/var/lib/nixos"
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];
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rollbackTo = "blank";
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dataset = "rpool/local/home";
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archiveLimit = 3;
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};
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users.users = [
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"crumb"
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@@ -1,84 +0,0 @@
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#!/usr/bin/env bb
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;;; TODO: option to either move OR copy
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(require '[clojure.core.match :refer [match]]
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'[babashka.cli :as cli]
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'[babashka.process :refer [$ check] :as p])
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(defn get-archive-path []
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(fs/path
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"/persist/previous"))
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(defn get-files []
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(let [diff (:out (check ($ {:out :string}
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"zfs" "diff" "-HF"
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"rpool/local/home@blank"
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"rpool/local/home")))]
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;; See zfs-diff(8) to understand what we're parsing here.
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(->> diff
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str/split-lines
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(map #(str/split % #"\s"))
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(filter #(and
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;; We only care to preserve /new/ content.
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(contains? #{"+" "M"} (first %))
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;; We only bother with plain old files. No directories,
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;; symlinks, etc.
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(= (second %) "F")))
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(map #(nth % 2)))))
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(defn move-out-of-my-way [file]
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;; No TCO. }:<
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(loop [n 0]
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(let [file' (format "%s-%d" file n)]
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(if (fs/exists? file')
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(recur (inc n))
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(do (fs/move file file')
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file')))))
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(defn archive-files [archive-path files]
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(let [new-archive (fs/path archive-path "home/new-archive")]
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(when (fs/exists? new-archive)
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(println "Warning: `new-archive' already exists... we'll rename it for you?")
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(move-out-of-my-way new-archive))
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(doseq [file files]
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(let [destination (fs/path
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new-archive
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(fs/relativize "/home" (fs/parent file)))]
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(fs/create-dirs destination)
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(fs/move file destination)))))
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(defn cycle-archives [archive-path n]
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"Delete the oldest archive path, and increment each previous path by one.
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More precisely,
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- Delete the archive path labeled `n` (the oldest allowed).
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- For each remaining path labeled 'i', relabel to 'i + 1'.
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- Lastly, we delete the path labeled `new-archive`, if it exists."
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(let [gp #(fs/path archive-path "home" (str %))]
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(fs/delete-if-exists (gp n))
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(doseq [i (range (dec n) 1 -1)]
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(when (fs/exists? (gp (dec i)))
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(fs/move (gp (dec i)) (gp i))))
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(when (fs/exists? (gp "new-archive"))
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(fs/move (gp "new-archive") (gp 1)))))
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(defn do-rollback []
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(let [proc (deref ($ "zfs" "rollback" "-r" "rpool/local/home@blank"))]
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(if (= (:exit proc) 0)
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(println (str "Successfully rolled back /home. "
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"Enjoy the fresh filesystem smell! }:D"))
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(println "Something went wrong rolling back /home... D:{"))))
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(defn -main []
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(let [n (if (< 0 (count *command-line-args*))
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(parse-long (first *command-line-args*))
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3)]
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(binding [p/*defaults*
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{:pre-start-fn #(println (str "+ " (str/join (:cmd %))))}]
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(let [archive-path (get-archive-path)
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files (get-files)]
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(archive-files archive-path files)
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(cycle-archives archive-path n)
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(do-rollback)))))
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(-main)
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@@ -14,45 +14,24 @@ in {
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};
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directories = mkOption {
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description = "";
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type = with types;
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listOf (coercedTo str (d: { directory = d; }) userDir);
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# type = with types;
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# listOf (coercedTo str (d: { directory = d; }) userDir);
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default = [];
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};
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files = mkOption {
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description = "";
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type = with types;
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listOf (coercedTo str (f: { file = f; }) userFile);
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# type = with types;
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# listOf (coercedTo str (f: { file = f; }) userFile);
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default = [];
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};
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};
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};
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config = mkIf cfg.enable {
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systemd.services.erase-home-darlings =
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let service = {
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description = "Rollback home to a blank state on boot";
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wantedBy = [
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"multi-user.target"
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];
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after = [
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"home.mount"
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];
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path = [ pkgs.zfs pkgs.babashka ];
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# unitConfig.DefaultDependencies = "no";
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serviceConfig = {
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Type = "oneshot";
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RemainAfterExit = true;
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ExecStart =
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let script = ./erase-home-darlings.clj;
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in ''${pkgs.babashka}/bin/bb "${script}" 3'';
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};
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stopIfChanged = false;
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restartIfChanged = false;
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};
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in if config.boot.initrd.systemd.enable
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then service
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else throw "sydnix.impermanence currently requires config.boot.initrd.systemd.enable'!";
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home.persistence."/persist/home/${config.home.username}" = {
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allowOther = true;
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directories = cfg.directories;
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files = cfg.files;
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};
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};
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}
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147
modules/nixos/erase-home-darlings.clj
Normal file
147
modules/nixos/erase-home-darlings.clj
Normal file
@@ -0,0 +1,147 @@
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#!/usr/bin/env bb
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;;; TODO: rewrite with fewer assumptions about the filesystem structure.
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;;; TODO: option to either move OR copy
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(require '[clojure.core.match :refer [match]]
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'[babashka.cli :as cli]
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'[clojure.pprint :as pp]
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'[babashka.process :refer [shell check process] :as p])
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(defn get-files [{:keys [rollback-to dataset]}]
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;; (prn rollback-to)
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;; (prn dataset)
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(let [snapshot (str dataset "@" rollback-to)
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diff (:out (shell {:out :string}
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"zfs diff -HF"
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snapshot
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dataset))]
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;; See zfs-diff(8) to understand what we're parsing here.
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(->> diff
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str/split-lines
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(map #(str/split % #"\s"))
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(filter #(and
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;; We only care to preserve /new/ content.
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(contains? #{"+" "M"} (first %))
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;; We only bother with plain old files. No directories,
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;; symlinks, etc.
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(= (second %) "F")))
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(map #(nth % 2)))))
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(defn move-out-of-my-way [file]
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;; No TCO. }:<
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(let [maximum-attempts 50]
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(loop [n 0]
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(let [file' (format "%s-%d" file n)]
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(if (fs/exists? file')
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(do (printf (str "Failed to rename `%s' to `%s', "
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"because the latter already exists.\n")
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file file')
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(if (< n maximum-attempts)
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(recur (inc n))
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(do (printf (str "We've tried to rename `%s' %d "
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"without success. This should "
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"never happen! Abort!")
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file (inc n))
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(System/exit 127))))
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(do (fs/move file file')
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file'))))))
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(defn archive-files [{:keys [archive-to]} files]
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(let [new-archive (fs/path archive-to "new-archive")]
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(when (fs/exists? new-archive)
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(println "Warning: `new-archive' already exists... we'll rename it for you?")
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(move-out-of-my-way new-archive))
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(doseq [file files]
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(let [destination (fs/path
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new-archive
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(fs/relativize "/home" (fs/parent file)))]
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(fs/create-dirs destination)
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(fs/move file destination)))))
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;; FIXME: This code could be a lot easier on the eyes. }:\
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(defn cycle-archives [{:keys [archive-to archive-limit]}]
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"Delete the oldest archive path, and increment each previous path by one.
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More precisely,
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- Delete the archive path labeled `n` (the oldest allowed).
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- For each remaining path labeled 'i', relabel to 'i + 1'.
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- Lastly, we delete the path labeled `new-archive`, if it exists."
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(let [gp (memoize #(fs/path archive-to (str %)))]
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(when (fs/exists? (gp archive-limit))
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(fs/delete-tree (gp archive-limit)))
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(doseq [i (range (dec archive-limit) 0 -1)]
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(when (fs/exists? (gp i))
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(fs/move (gp i) (gp (inc i)))))
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(when (fs/exists? (gp "new-archive"))
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(fs/move (gp "new-archive") (gp 1)))))
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(defn do-rollback [{:keys [dataset rollback-to]}]
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(let [proc (shell "zfs" "rollback" "-r" (str dataset "@" rollback-to))]
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(if (= (:exit proc) 0)
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(println (str "Successfully rolled back /home. "
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"Enjoy that fresh filesystem smell! }:D"))
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(println "Something went wrong rolling back /home... D:{"))))
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(def zfs-dataset?
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;; We memoise an anonymous procedure because we want the command to be run on
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;; the first invocation of `zfs-dataset?`, *not* when this file's top-level is
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;; first evaluated. Naïvely, it's reasonable to think we should instead do
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;; something like
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;; (def zfs-dataset?
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;; (let [datasets <call zfs list>]
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;; (fn [x] (contains? datasets x))))
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;; but that would call zfs (and potentially throw) far too early to make sense.
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(let [get-datasets (memoize
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(fn []
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(->> (:out (shell {:out :string} "ls" "-la"))
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str/split-lines
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(map #(first (str/split % #"\s")))
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set)))]
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(fn [x]
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(contains? (get-datasets) x))))
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(def cli-spec
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{:spec
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{:archive-limit {:coerce :int
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:alias :n
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:validate #(pos? %)
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:default 3
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:desc "Number of archives to save at a time."}
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:dataset {:coerce :string
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;; :validate zfs-dataset?
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:require true
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:desc "Dataset to be archived and rolled back."}
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:rollback-to {:coerce :string
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;; TODO: Validate snapshot.
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:require true
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:desc "Snapshot to rollback to."}
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:archive-to {:coerce :string
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:default "/persist/previous/home"
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:desc "The path under which archives will be stored."}
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:error-fn
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(fn [{:keys [spec type cause msg option] :as data}]
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(when (= :org.babashka/cli type)
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(case cause
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:require
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(println
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(format "Missing required argument: %s\n" option))))
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(System/exit 1))}})
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(defmacro with-echoed-shell-commands [& body]
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(let [print-cmd #(println (str "+ " (str/join (:cmd %))))]
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`(binding [p/*defaults* {:pre-start-fn ~print-cmd}]
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~@body)))
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(defmacro with-echoed-shell-commands [& body]
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`(do ~@body))
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(defn -main [opts]
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(pp/pprint opts)
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(with-echoed-shell-commands
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(let [files (get-files opts)]
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(archive-files opts files)
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(cycle-archives opts)
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(do-rollback opts))))
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(-main (cli/parse-opts *command-line-args* cli-spec))
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@@ -26,6 +26,21 @@ in {
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type = with types; listOf anything;
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default = [];
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};
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rollbackTo = mkOption {
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type = types.str;
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};
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archiveTo = mkOption {
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type = types.str;
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default = "/persist/previous/home";
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};
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dataset = mkOption {
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type = types.str;
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};
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archiveLimit = mkOption {
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type = types.ints.positive;
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default = 3;
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};
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};
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};
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@@ -34,33 +49,58 @@ in {
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zfs
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];
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boot.initrd.systemd.services.erase-darlings = {
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description = "Rollback filesystem to a blank state on boot";
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boot.initrd.systemd.services.erase-darlings =
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let service = {
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description = "Rollback filesystem to a blank state on boot";
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wantedBy = [
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"initrd.target"
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];
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after = [
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# "zfs-import.service"
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"zfs-import-rpool.service"
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];
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before = [
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"sysroot.mount"
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];
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path = [ pkgs.zfs ];
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unitConfig.DefaultDependencies = "no";
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serviceConfig = {
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Type = "oneshot";
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RemainAfterExit = true;
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};
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script = /* bash */ ''
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zfs rollback -r rpool/local/root@blank \
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&& echo ">> >> rollback complete << <<"
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'';
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};
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in if config.boot.initrd.systemd.enable
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then service
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else throw "sydnix.impermanence currently requires config.boot.initrd.systemd.enable'!";
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systemd.services.erase-home-darlings = {
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description = "Rollback home to a blank state on boot";
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wantedBy = [
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"initrd.target"
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"multi-user.target"
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];
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after = [
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# "zfs-import.service"
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"zfs-import-rpool.service"
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"home.mount"
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];
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before = [
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"sysroot.mount"
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];
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path = [ pkgs.zfs ];
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unitConfig.DefaultDependencies = "no";
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path = [ pkgs.zfs pkgs.babashka ];
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# unitConfig.DefaultDependencies = "no";
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serviceConfig = {
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Type = "oneshot";
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RemainAfterExit = true;
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ExecStart =
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let script = ./erase-home-darlings.clj;
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in ''${pkgs.babashka}/bin/bb "${script}" -n "${toString cfg.archiveLimit}" --dataset "${cfg.dataset}" --rollback-to "${cfg.rollbackTo}"'';
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};
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script = /* bash */ ''
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zfs rollback -r rpool/local/root@blank \
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&& echo ">> >> rollback complete << <<"
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'';
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stopIfChanged = false;
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restartIfChanged = false;
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};
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environment.persistence."/persist" = {
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directories = cfg.directories;
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files = cfg.files;
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directories = cfg.directories;
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files = cfg.files;
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};
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};
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}
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@@ -1,6 +1,12 @@
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{ config, lib, pkgs, ... }:
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|
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{
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home.stateVersion = "18.09";
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home.packages = [ pkgs.hello ];
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home = { config, lib, pkgs, ... }: {
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sydnix.impermanence = {
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enable = true;
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};
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home = {
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stateVersion = "18.09";
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packages = [ pkgs.hello ];
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};
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||||
};
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}
|
||||
|
||||
Reference in New Issue
Block a user