mirror of
https://github.com/kevinveenbirkenbach/docker-volume-backup.git
synced 2026-08-01 12:34:50 +00:00
Kevin Veen-Birkenbach
b10d50efbe
Four defects in the snapshot mode 3.2.0 introduced. The resolver dropped the trailing separator get_storage_path puts on a volume path, because os.path.abspath strips it. rsync reads "dir" as "copy the directory" where "dir/" means "copy its contents", so every snapshot generation landed at <volume>/files/_data/... while the live path lands at <volume>/files/... . Restores read the live layout, and --link-dest found nothing to match against the previous generation. The e2e never caught it because its driver appended the separator by hand. Snapshot teardown was fatal and masking. A busy `btrfs subvolume delete` raised out of the finally, which skipped the generation stamp and the compose handling on a run whose data was already complete, and replaced whatever the body had raised. The leftover is reported instead; removing it is a cleanup problem, not a reason to discard a good generation. A volume created after the snapshot was taken aborted the whole run: the volume list is enumerated inside the snapshot context, and nothing is stopped in snapshot mode, so the host keeps creating volumes for the duration of the copy. Such a volume is now copied live with a warning, which is exactly what the pre-snapshot code did for it. The snapshot pass compares by content again. 3.2.0 dropped --checksum because a snapshot source cannot move, which is true, but the comparison that matters is against --link-dest: a file that changed while keeping its size and whole-second mtime was hard-linked stale out of the previous generation, and the single snapshot pass had no authoritative pass to repair it the way the live path does. It is still one pass against two. --hard-restart-projects is refused alongside --snapshot, the same way --shutdown already is: the flag exists for stacks whose database cannot be backed up hot, which is what a snapshot removes. Tests: the trailing separator, both teardown behaviours, the new refusal, and app.main driving the snapshot branch - the caller that runs in production, which no test had exercised and where the layout defect therefore stayed invisible. The e2e driver now feeds the resolver the string shape get_storage_path really produces. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
135 lines
5.2 KiB
Python
135 lines
5.2 KiB
Python
"""Contract of the filesystem snapshot used to capture volumes atomically."""
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from __future__ import annotations
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import unittest
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from baudolo.backup.shell import BackupException
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from baudolo.backup.snapshot import SnapshotError, volume_snapshot
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class Runner:
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def __init__(self, replies: dict[str, list[str]] | None = None) -> None:
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self.calls: list[str] = []
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self.replies = replies or {}
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def __call__(self, command: str) -> list[str]:
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self.calls.append(command)
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for prefix, reply in self.replies.items():
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if command.startswith(prefix):
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return reply
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return []
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class TestBtrfs(unittest.TestCase):
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def test_it_creates_a_read_only_snapshot_beside_the_subject(self) -> None:
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run = Runner()
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with volume_snapshot("btrfs", "/var/lib/docker", "20260731", run=run):
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pass
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self.assertEqual(
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run.calls[0],
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"btrfs subvolume snapshot -r /var/lib/docker /var/lib/.baudolo-20260731",
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)
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def test_it_removes_the_snapshot_afterwards(self) -> None:
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run = Runner()
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with volume_snapshot("btrfs", "/var/lib/docker", "20260731", run=run):
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pass
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self.assertEqual(run.calls[-1], "btrfs subvolume delete /var/lib/.baudolo-20260731")
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def test_it_maps_a_volume_path_into_the_snapshot(self) -> None:
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run = Runner()
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with volume_snapshot("btrfs", "/var/lib/docker", "20260731", run=run) as resolve:
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self.assertEqual(
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resolve("/var/lib/docker/volumes/postgres_data/_data"),
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"/var/lib/.baudolo-20260731/volumes/postgres_data/_data",
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)
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def test_it_keeps_the_trailing_slash_rsync_reads_as_contents(self) -> None:
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run = Runner()
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with volume_snapshot("btrfs", "/var/lib/docker", "20260731", run=run) as resolve:
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self.assertEqual(
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resolve("/var/lib/docker/volumes/postgres_data/_data/"),
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"/var/lib/.baudolo-20260731/volumes/postgres_data/_data/",
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)
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def test_it_removes_the_snapshot_even_when_the_body_raises(self) -> None:
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run = Runner()
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with self.assertRaises(ZeroDivisionError):
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with volume_snapshot("btrfs", "/var/lib/docker", "20260731", run=run):
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raise ZeroDivisionError
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self.assertTrue(run.calls[-1].startswith("btrfs subvolume delete"))
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class TestZfs(unittest.TestCase):
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def _run(self) -> Runner:
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return Runner({"zfs list": ["tank/docker"]})
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def test_it_snapshots_the_dataset_mounted_at_the_subject(self) -> None:
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run = self._run()
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with volume_snapshot("zfs", "/var/lib/docker", "20260731", run=run):
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pass
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self.assertIn("zfs snapshot tank/docker@baudolo-20260731", run.calls)
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def test_it_destroys_the_snapshot_afterwards(self) -> None:
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run = self._run()
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with volume_snapshot("zfs", "/var/lib/docker", "20260731", run=run):
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pass
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self.assertEqual(run.calls[-1], "zfs destroy tank/docker@baudolo-20260731")
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def test_it_maps_a_volume_path_through_the_dot_zfs_directory(self) -> None:
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run = self._run()
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with volume_snapshot("zfs", "/var/lib/docker", "20260731", run=run) as resolve:
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self.assertEqual(
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resolve("/var/lib/docker/volumes/postgres_data/_data"),
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"/var/lib/docker/.zfs/snapshot/baudolo-20260731/volumes/postgres_data/_data",
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)
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def test_an_unmounted_dataset_is_an_error(self) -> None:
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run = Runner({"zfs list": [""]})
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with self.assertRaises(SnapshotError):
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with volume_snapshot("zfs", "/var/lib/docker", "20260731", run=run):
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pass
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class TestRejections(unittest.TestCase):
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def test_an_unknown_kind_is_rejected(self) -> None:
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run = Runner()
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with self.assertRaises(SnapshotError):
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with volume_snapshot("ext4", "/var/lib/docker", "20260731", run=run):
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pass
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self.assertEqual(run.calls, [])
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def test_a_path_outside_the_subject_is_rejected(self) -> None:
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run = Runner()
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with volume_snapshot("btrfs", "/var/lib/docker", "20260731", run=run) as resolve:
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with self.assertRaises(SnapshotError):
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resolve("/etc/passwd")
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def test_the_subject_itself_resolves_to_the_snapshot_root(self) -> None:
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run = Runner()
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with volume_snapshot("btrfs", "/var/lib/docker", "20260731", run=run) as resolve:
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self.assertEqual(resolve("/var/lib/docker"), "/var/lib/.baudolo-20260731")
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class Busy(Runner):
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def __call__(self, command: str) -> list[str]:
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if command.startswith("btrfs subvolume delete"):
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raise BackupException("target is busy")
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return super().__call__(command)
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class TestRemovalFailure(unittest.TestCase):
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def test_a_failed_removal_does_not_fail_a_completed_run(self) -> None:
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with volume_snapshot("btrfs", "/var/lib/docker", "20260731", run=Busy()):
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pass
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def test_a_failed_removal_does_not_mask_the_body(self) -> None:
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with self.assertRaises(ZeroDivisionError):
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with volume_snapshot("btrfs", "/var/lib/docker", "20260731", run=Busy()):
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raise ZeroDivisionError
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if __name__ == "__main__":
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unittest.main()
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