Kevin Veen-BirkenbachandClaude Opus 5
07d819cb41
rsync -a expands to -rlptgoD, so the backup stored neither extended attributes nor ACLs nor hardlinks while the restore side asks for -aHAX. A generation therefore never held what a restore wants back, and rsync faithfully mirrored a snapshot that has none. Reproduced end to end against a source carrying user.oc.* attributes and a hardlink: with the old argv, getfattr -d -R over the generation returns nothing and the hardlink splits into two inodes; with -aHAX both sides come back identical to the source. That is the shape in which an OpenCloud volume survived a disaster-recovery drill with its files intact and its storage metadata gone, so its posix driver skipped every space it could no longer read. restore/files.py had the same gap on this repository's own restore path. Two consequences worth knowing. The first backup after this re-copies every attribute-carrying volume once, because rsync declines to hardlink against a generation whose xattrs do not match. And a backup destination on a filesystem without xattr support now fails the run instead of producing a generation that cannot be restored. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
65 lines
2.3 KiB
Python
65 lines
2.3 KiB
Python
"""Restore a volume's file tree by writing into its mountpoint.
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That shortcut only holds for a plain local volume, where the mountpoint *is*
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the storage. A volume with driver options - NFS, a bind device, tmpfs - keeps
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the same ``/var/lib/docker/volumes/<name>/_data`` path, but docker mounts the
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real backing store over it on demand and unmounts it again when the last
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consumer stops. Writing there while nothing has it mounted lands in the empty
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directory underneath, is hidden by the next mount, and rsync reports success.
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"""
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from __future__ import annotations
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import os
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import sys
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from pathlib import Path
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from .run import docker_volume_exists, run, stdout_of
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INSPECT_FORMAT = (
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"{{ .Mountpoint }}|{{ .Driver }}|{{ if .Options }}opts{{ else }}plain{{ end }}"
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)
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def restore_volume_files(volume_name: str, backup_files_dir: str) -> int:
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if not Path(backup_files_dir).is_dir():
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print(f"ERROR: backup files dir not found: {backup_files_dir}", file=sys.stderr)
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return 2
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if not docker_volume_exists(volume_name):
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print(f"Volume {volume_name} does not exist. Creating...")
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run(["docker", "volume", "create", volume_name])
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else:
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print(f"Volume {volume_name} already exists.")
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cp = run(
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["docker", "volume", "inspect", "--format", INSPECT_FORMAT, volume_name],
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capture=True,
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)
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fields = stdout_of(cp).split("|")
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mountpoint = fields[0] if fields else ""
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if not mountpoint:
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print(
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f"ERROR: could not resolve mountpoint for volume {volume_name}",
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file=sys.stderr,
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)
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return 2
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driver, options = ([*fields, "local", "plain"])[1:3]
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if (driver != "local" or options == "opts") and not os.path.ismount(mountpoint):
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print(
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f"ERROR: volume {volume_name} has a backing store of its own "
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f"(driver {driver}) but nothing has it mounted; writing to "
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f"{mountpoint} now would land under the mount and be lost. "
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"Start a container that mounts the volume, then restore again.",
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file=sys.stderr,
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)
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return 2
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# rsync reads "dir/" as its contents and "dir" as the directory itself.
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src = f"{Path(backup_files_dir)}{os.sep}"
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dest = f"{Path(mountpoint)}{os.sep}"
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run(["rsync", "-aHAX", "-vv", "--delete", src, dest])
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print("File restore complete.")
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return 0
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