112 lines
3.3 KiB
Python
112 lines
3.3 KiB
Python
#!/usr/bin/env python3
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from json import load
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from subprocess import check_call, check_output
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from sys import argv
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from time import time
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NODE = argv[1]
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NOW = int(time())
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DAY_SECONDS = 60 * 60 * 24
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INTERVALS = {
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'daily': DAY_SECONDS,
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'weekly': 7 * DAY_SECONDS,
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'monthly': 30 * DAY_SECONDS,
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}
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buckets = {}
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def syslog(msg):
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check_output(['logger', '-t', f'backup-{NODE}', msg])
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with open(f'/etc/backup-server/config.json', 'r') as f:
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server_settings = load(f)
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with open(f'/etc/backup-server/clients/{NODE}', 'r') as f:
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client_settings = load(f)
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# get all existing snapshots for NODE
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for line in check_output('LC_ALL=C zfs list -H -t snapshot -o name', shell=True).splitlines():
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line = line.decode('UTF-8')
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if line.startswith('{}/{}@'.format(server_settings['zfs-base'], NODE)):
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_, snapname = line.split('@', 1)
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if 'zfs-auto-snap' in snapname:
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# migration from auto-snapshots, ignore
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continue
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ts, bucket = snapname.split('-', 1)
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buckets.setdefault(bucket, set()).add(int(ts))
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syslog(f'classified {line} as {bucket} from {ts}')
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# determine if we need to create a new snapshot
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for bucket in INTERVALS.keys():
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snapshots = sorted(buckets.get(bucket, set()))
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if snapshots:
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last_snap = snapshots[-1]
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delta = NOW - last_snap
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fresh_age = INTERVALS[bucket] - DAY_SECONDS
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if delta > fresh_age:
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# last snapshot is older than what we want. create a new one.
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check_call(
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'zfs snapshot {}/{}@{}-{}'.format(
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server_settings['zfs-base'],
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NODE,
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NOW,
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bucket,
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),
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shell=True,
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)
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buckets.setdefault(bucket, set()).add(NOW)
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syslog(f'created new snapshot {NOW}-{bucket}')
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else:
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syslog(f'existing snapshot {last_snap}-{bucket} is fresh enough')
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else:
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check_call(
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'zfs snapshot {}/{}@{}-{}'.format(
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server_settings['zfs-base'],
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NODE,
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NOW,
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bucket,
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),
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shell=True,
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)
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buckets.setdefault(bucket, set()).add(NOW)
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syslog(f'created initial snapshot {NOW}-{bucket}')
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# finally, see if we can delete any snapshots, because they are old enough
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for bucket in INTERVALS.keys():
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snapshots = sorted(buckets.get(bucket, set()))
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if not snapshots:
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syslog(f'something is wrong, there are no snapshots for {bucket}')
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continue
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keep_age = INTERVALS[bucket] * client_settings[bucket]
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# oldest snapshots come first
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for ts in snapshots[:-int(client_settings[bucket])]:
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delta = NOW - ts
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if delta >= keep_age:
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check_call(
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'zfs destroy {}/{}@{}-{}'.format(
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server_settings['zfs-base'],
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NODE,
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ts,
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bucket,
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),
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shell=True,
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)
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syslog(f'removing snapshot {ts}-{bucket}, age {delta}, keep_age {keep_age}')
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else:
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syslog(f'keeping snapshot {ts}-{bucket}, age not reached')
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for ts in snapshots[int(client_settings[bucket]):]:
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syslog(f'keeping snapshot {ts}-{bucket}, count')
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