1 files changed, 104 insertions, 0 deletions

diff --git a/snap.py b/snap.py
new file mode 100644
index 00000000..cc75739b
--- /dev/null
+++ b/snap.py
@@ -0,0 +1,104 @@
+#! /usr/bin/env nix-shell
+#! nix-shell -i python -p "python3.withPackages (p: with p; [dateutil python-unshare])"
+
+import os
+import argparse
+import sys
+from datetime import (datetime,timezone)
+from dateutil.tz import (tzlocal)
+import subprocess
+import json
+
+from tempfile import TemporaryDirectory
+
+import pathlib
+
+import unshare
+
+
+def borg_lv(lv, size_percent, target, archive_prefix, **args):
+    vgp = lv.split('/')
+    lvn = vgp[-1]
+    snn = f'{lvn}_snap_{datetime.utcnow().strftime("%Y%m%dT%H%MZ")}'
+    sn = "/".join([*vgp[:-1], snn])
+
+    try:
+        subprocess.run(['lvcreate', f'-l{size_percent}%ORIGIN', '-s', '-n', snn, lv], stdin=subprocess.DEVNULL, check=True)
+
+        creation_time = None
+        with subprocess.Popen(['lvs', '--reportformat=json', '-olv_time', sn], stdout=subprocess.PIPE) as proc:
+            res = json.load(proc.stdout)
+            creation_time = datetime.strptime(res['report'][0]['lv'][0]['lv_time'], '%Y-%m-%d %H:%M:%S %z').astimezone(timezone.utc)
+
+        with TemporaryDirectory(prefix=f'{snn}_') as tmpdir:
+            child = os.fork()
+            if child == 0:
+                unshare.unshare(unshare.CLONE_NEWNS)
+                subprocess.run(['mount', '--make-rprivate', '/'], check=True)
+                chroot = pathlib.Path(tmpdir) / 'chroot'
+                upper = pathlib.Path(tmpdir) / 'upper'
+                work = pathlib.Path(tmpdir) / 'work'
+                for path in [chroot,upper,work]:
+                    path.mkdir()
+                subprocess.run(['mount', '-t', 'overlay', 'overlay', '-o', f'lowerdir=/,upperdir={upper},workdir={work}', chroot], check=True)
+                bindMounts = ['nix', 'run', 'proc', 'dev', 'sys', pathlib.Path(os.path.expanduser('~')).relative_to('/')]
+                if 'SSH_AUTH_SOCK' in os.environ:
+                    bindMounts.append(pathlib.Path(os.environ['SSH_AUTH_SOCK']).parent.relative_to('/'))
+                for bindMount in bindMounts:
+                    (chroot / bindMount).mkdir(parents=True,exist_ok=True)
+                    subprocess.run(['mount', '--bind', pathlib.Path('/') / bindMount, chroot / bindMount], check=True)
+                os.chroot(chroot)
+                os.chdir('/')
+                dir = pathlib.Path('/borg')
+                dir.mkdir(parents=True,exist_ok=True)
+                subprocess.run(['mount', f'/dev/{sn}', dir], check=True)
+
+                archive_lvn=lvn
+                if "/".join(vgp[:-1]) != archive_prefix.split('.')[-2]:
+                    archive_lvn=f'{"_".join(vgp[:-1])}_{archive_lvn}'
+                archive=f'{target}::{archive_prefix}{archive_lvn}-{{utcnow}}'
+
+                env = os.environ.copy()
+                create_args = ['borg',
+                               'create',
+                               '--lock-wait=600',
+                               '--one-file-system',
+                               '--compression=auto,zstd,10',
+                               '--chunker-params=10,23,16,4095',
+                               f'--timestamp={creation_time.strftime("%Y-%m-%dT%H:%M:%S")}',
+                               '--show-rc',
+                               '--progress',
+                               '--list',
+                               '--filter=AMEi-x?',
+                               '--stats',
+                               '--patterns-from=.backup-vidhar',
+                               '--exclude-caches',
+                               '--keep-exclude-tags'
+                               ]
+                env['BORG_FILES_CACHE_SUFFIX'] = "_".join(vgp)
+                create_args += [archive]
+                subprocess.run(create_args, cwd=dir, check=True, env=env)
+
+                os._exit(0)
+            else:
+                while True:
+                    waitpid, waitret = os.wait()
+                    if waitret != 0:
+                        sys.exit(waitret)
+                    if waitpid == child:
+                        break
+    finally:
+        subprocess.run(['lvremove', '--force', sn], stdin=subprocess.DEVNULL, check=True)
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('lv', metavar='LV')
+    parser.add_argument('--size-percent', metavar='PERCENT', type = float, default=10)
+    parser.add_argument('--target', metavar='REPO', default='borg.vidhar:.')
+    parser.add_argument('--archive-prefix', metavar='REPO', default='yggdrasil.niflheim.ymir.')
+    args = parser.parse_args()
+
+    return borg_lv(**vars(args))
+
+if __name__ == "__main__":
+    sys.exit(main())