84 lines
2.6 KiB
Python
84 lines
2.6 KiB
Python
#!/usr/bin/env python3
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import re
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from datetime import datetime
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from json import loads
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from subprocess import check_call, check_output
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from sys import argv
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def list_datasets():
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datasets = set()
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for line in check_output(['zfs', 'list', '-H', '-o', 'name']).splitlines():
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line = line.decode('UTF-8')
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for prefix in metadata.get('snapshot_never', set()):
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if line.startswith(prefix):
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break
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else:
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datasets.add(line)
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return datasets
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def get_filtered_snapshots_for_dataset(ds):
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all_snapshots = check_output(['zfs', 'list', '-H', '-o', 'name', '-t', 'snapshot']).decode('UTF-8').splitlines()
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prefix = '{}@zfs-auto-snap_{}-'.format(ds, label)
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snapshots = set()
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for i in sorted(all_snapshots):
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if i.startswith(prefix):
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snapshots.add(i)
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return snapshots
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def delete_snapshot(snap):
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assert '@' in snap, 'BUG! Dataset "{}" has no @!'.format(snap)
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print('deleting snapshot {}'.format(snap))
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check_call(['zfs', 'destroy', snap])
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def create_snapshot(ds, label, now):
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check_call(['zfs', 'snapshot', '{}@zfs-auto-snap_{}-{}'.format(ds, label, now)])
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print('created snapshot {}@zfs-auto-snap_{}-{}'.format(ds, label, now))
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label = argv[1]
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with open('/etc/zfs-snapshot-config.json', 'r') as fp:
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metadata = loads(fp.read())
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default_retain = metadata['retain_defaults'][label]
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now = datetime.now().strftime('%F-%H%M')
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snapshots_created = False
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for ds in list_datasets():
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retain = int(metadata.get('retain_per_dataset', {}).get(ds, {}).get(label, default_retain))
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if retain > 0:
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create_snapshot(ds, label, now)
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snapshots_created = True
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existing_snapshots = get_filtered_snapshots_for_dataset(ds)
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if retain > 0:
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# Why +1 here? Because we're specifying the amount of hours we want
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# to go back in time, not the amount of snapshots we want to keep.
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# Stating '1 month' does mean 'i want to be able to go back atleast
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# one monthly snapshot', not 'keep one monthly snapshot'. If we only
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# kept one snapshot, that wouldn't be possible for most of the time,
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# because the monthly snapshot is actually less than a month old.
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snapshots_to_keep = retain+1
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for snapshot in sorted(existing_snapshots)[:-snapshots_to_keep]:
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delete_snapshot(snapshot)
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else:
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for snapshot in existing_snapshots:
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delete_snapshot(snapshot)
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with open('/var/tmp/zfs-auto-snapshot.status', 'w') as fp:
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fp.write('{}\n'.format(datetime.now().strftime('%s') if snapshots_created else 0))
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