matthias/zfs-smart-snapshot
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Initial working implementation, missing command line parsing

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Matthias Blankertz
2021-09-30 21:46:35 +02:00
parent 0e1d8aeb8b
commit 9d92d78c9e
1 changed files with 43 additions and 12 deletions
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55
zfs_smart_snapshot/main.py
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@@ -1,8 +1,12 @@
from datetime import datetime, timezone
from dateutil.relativedelta import relativedelta
from pprint import pprint
import subprocess
import sys
from pprint import pprint
# TODO: Argument parsing
verbose = True
dry_run = False
def keep_time(now, snapshots, convert, delta, count):
@@ -11,9 +15,10 @@ def keep_time(now, snapshots, convert, delta, count):
return keep
start = convert(now) - delta*(count-1)
for snapshot in snapshots:
if snapshot >= start:
snapdate = datetime.strptime(snapshot, 'zfs-smart-snap-%Y-%m-%d-%H%M').replace(tzinfo=timezone.utc)
if snapdate >= start:
keep.add(snapshot)
start = convert(snapshot) + delta
start = convert(snapdate) + delta
if start > now:
break
return keep
@@ -49,7 +54,7 @@ def snapshots_to_keep(now, snapshots, yearly=0, monthly=0, daily=0, hourly=0, fr
keep.update(keep_day(now, snapshots, daily))
keep.update(keep_hour(now, snapshots, hourly))
keep.update(keep_frequent(now, snapshots, frequently))
return sorted(list(keep))
return keep
def parse_int(fields, name, fieldname):
@@ -59,14 +64,13 @@ def parse_int(fields, name, fieldname):
return int(fields[fieldname])
except ValueError:
print(f"Warning: Could not parse value {fields[fieldname]} for fs/zvol {name} prop {fieldname}",
output=sys.stderr)
file=sys.stderr)
return -1
def zfs_list(fieldnames, args):
proc = subprocess.run(['/usr/sbin/zfs', 'list', '-H', '-o', ','.join(['name'] + fieldnames)] + args,
capture_output=True, check=True, encoding='UTF-8')
pprint(proc.args)
if not fieldnames:
result = list()
else:
@@ -96,7 +100,6 @@ def read_snapshots(fs_to_snap):
result = dict()
for name in raw_list:
fs, snap = name.split('@')
print(f'{fs}, {snap}')
if snap.startswith('zfs-smart-snap'):
result[fs] = result.get(fs, []) + [snap]
return result
@@ -113,25 +116,53 @@ def find_latest_snapshots(existing_snaps):
def written_since_last(fs, snap):
proc = subprocess.run(['/usr/sbin/zfs', 'list', '-Hp', '-o', f'written@{snap}', fs],
check=True, capture_output=True, encoding="UTF-8")
return int(proc.stdout) > 0
res = int(proc.stdout)
if verbose and res == 0:
print(f"{fs} not written since {snap}, skipping")
return res > 0
def main():
now = datetime.now(timezone.utc).replace(second=0, microsecond=0)
if verbose:
print(f"zfs_smart_snapshot running at {now.strftime('%Y-%m-%d-%H%M')}")
props = read_snapshot_props()
pprint(props)
fs_to_snap = [k for k, v in props.items() if v['snapshot']]
if fs_to_snap:
existing_snaps = read_snapshots(fs_to_snap)
pprint(existing_snaps)
latest_snaps = find_latest_snapshots(existing_snaps)
fs_to_really_snap = [fs for fs in fs_to_snap if fs not in latest_snaps or
written_since_last(fs, latest_snaps[fs])]
if fs_to_really_snap:
pools = {fs.split('/')[0] for fs in fs_to_really_snap}
snapname = 'zfs-smart-snap-' + now.strftime('%Y-%m-%d-%H%M')
subprocess.run(['/usr/sbin/zfs', 'snapshot'] + [f'{fs}@{snapname}' for fs in fs_to_really_snap], check=True)
snaps_to_create = [f'{fs}@{snapname}' for fs in fs_to_really_snap]
if dry_run or verbose:
phrase = "Would" if dry_run else "Will"
print(f"{phrase} create snapshots " + ", ".join(snaps_to_create))
if not dry_run:
for pool in pools:
subprocess.run(['/usr/sbin/zfs', 'snapshot'] + [snap for snap in snaps_to_create if snap.startswith(pool)], check=True)
for fs in fs_to_really_snap:
existing_snaps[fs] = existing_snaps.get(fs, []) + [snapname]
# TODO: Cleanup expired snapshots
to_delete = []
for fs in (fs for fs in fs_to_snap if fs in existing_snaps):
to_keep = snapshots_to_keep(now, existing_snaps[fs], props[fs]['yearly'], props[fs]['monthly'], props[fs]['daily'], props[fs]['hourly'], props[fs]['frequently'])
# Always keep latest snapshot. If it would be deleted (e.g. due to a incoherent snapshot history configuration) this could confuse the
# 'written since last snapshot' logic and cause a cycle of creating/deleteing/creating the snapshot on an idle file system
if existing_snaps[fs][-1] not in to_keep:
print(f"Warning: Latest snap {fs}@{existing_snaps[fs][-1]} not preserved by retention policy, keeping anyways", file=sys.stderr)
to_keep.add(existing_snaps[fs][-1])
to_delete += (f'{fs}@{snap}' for snap in set(existing_snaps[fs]).difference(to_keep))
if not dry_run:
if verbose and len(to_delete) > 0:
print("Will destroy snapshots " + ", ".join(sorted(to_delete)))
for delete_snap in to_delete:
subprocess.run(['/usr/sbin/zfs', 'destroy', delete_snap], check=True)
elif len(to_delete) > 0:
print("Would destroy snapshots " + ", ".join(sorted(to_delete)))
if __name__ == "__main__":