Import zfs snapshots service as Arch package into git

.gitignore

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+/*.src.tar.gz
+/*.pkg.tar.zst

PKGBUILD

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+# Maintainer: Daniel <daniel.de.clooet@yoursurprise.com>
+pkgname=zfs-snapshotter
+pkgver=0.0.1
+pkgrel=1
+pkgdesc='Systemd snapshotter tool'
+
+source=("zfs-daily-snapshot@.timer" "zfs-daily-snapshot@.service" "zfs-snapshot.rb")
+arch=('x86_64' 'aarch64' 'armv7h')
+depends=('systemd' 'zfs' 'ruby')
+
+sha256sums=('SKIP'
+            'SKIP'
+            'SKIP')
+
+package() {
+  install -Dm755 "${srcdir}/zfs-snapshot.rb" "${pkgdir}/usr/bin/zfs-snapshot.rb"
+
+  install -Dm644 "${srcdir}/zfs-daily-snapshot@.timer" "${pkgdir}/etc/systemd/system/zfs-daily-snapshot@.timer"
+  install -Dm644 "${srcdir}/zfs-daily-snapshot@.service" "${pkgdir}/etc/systemd/system/zfs-daily-snapshot@.service"
+}

README.md

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+# ZFS Snapshotter
+
+This is my personal opiniated package for automatically creating and cleaning up ZFS snapshots.
+
+## Usage:
+- Clone this repository.
+- Build and install: `$ makepkg -Si`
+- Enable the systemd timer for your datasets:
+ - Use `-` instead of `/`, due to systemd encoding: `# systemctl enable --now zfs-daily-snapshot@pool-my-dataset.timer`

zfs-daily-snapshot@.service

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+[Unit]
+Description=Create a ZFS snapshot for %I
+DefaultDependencies=no
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/zfs-snapshot.rb "%I"

zfs-daily-snapshot@.timer

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+[Unit]
+Description=Create a daily ZFS snapshot for %I
+
+[Timer]
+OnCalendar=daily
+Persistent=true
+
+[Install]
+WantedBy=timers.target

zfs-snapshot.rb

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+#!/usr/bin/env ruby
+
+require 'date'
+
+SNAPSHOTS_TO_RETAIN = 7
+SNAPSHOT_FORMAT = "daily-%Y-%m-%d"
+
+input = ARGV
+
+def usage
+  puts "Usage: "
+  puts "    #{$PROGRAM_NAME} <pool>"
+
+  exit -1
+end
+
+def run_command(*cmd)
+  pipe = IO.popen(cmd)
+  stdout = pipe.read
+  puts stdout
+  pipe.close
+
+  return stdout, $?.success?
+end
+
+class Array
+  def drop_tail(n)
+    slice(0...(length - n))
+  end
+end
+
+class Dataset
+  def initialize(name)
+    _, dataset_exists = run_command("zfs", "list", "-H", name)
+    raise "No such pool: #{name}" unless dataset_exists
+
+    @name = name
+  end
+
+  def has_snapshot(name)
+    _, snapshot_exists = run_command("zfs", "list", "-H", "#{@name}@#{name}")
+    return snapshot_exists
+  end
+
+  def create_snapshot_today
+    current_snapshot_name = Date.today.strftime(SNAPSHOT_FORMAT)
+    raise "Snapshot already created: #{@name}@#{current_snapshot_name}" if has_snapshot(current_snapshot_name)
+
+    _, made_snapshot = run_command("zfs", "snapshot", "#{@name}@#{current_snapshot_name}")
+    raise "Could not create new snapshot #{@name}@#{current_snapshot_name}" unless made_snapshot
+  end
+
+  def get_all_snapshots
+    all_snapshots, could_list_all_snapshot = run_command("zfs", "list", "-t", "snapshot", "-H", @name)
+    raise "Could not list snapshots for #{@name}" unless could_list_all_snapshot
+
+    return all_snapshots.lines.map { |line| line.split("\t").first }.map { |snapshot_name| snapshot_name.split("@").last }
+  end
+
+  def clean_up_old_snapshots
+    snapshots_to_delete = get_all_snapshots.drop_tail(SNAPSHOTS_TO_RETAIN)
+    p snapshots_to_delete
+
+    return if snapshots_to_delete.length == 0
+
+    output, could_delete_old_snapshots = run_command("zfs", "destroy", "#{@name}@#{snapshots_to_delete.first}%#{snapshots_to_delete.last}")
+    raise "Could not delete old snapshots for #{@name}" unless could_delete_old_snapshots
+  end
+end
+
+usage unless input.length == 1
+usage if input[0] == "-h" or input[0] == "--help"
+
+dataset = Dataset.new input[0]
+dataset.create_snapshot_today
+dataset.clean_up_old_snapshots