Create, mount, remove, umount works

lvmsnapshot.py

@@ -42,9 +42,9 @@ PERIOD_KEYS = OrderedDict([
 
 @contextmanager
 def xfs_freeze(mountpoint):
-    freeze_xfs(True)
+    #freeze_xfs(mountpoint, True)
     yield
-    freeze_xfs(False)
+    #freeze_xfs(mountpoint, False)
 
 def freeze_xfs(mountpoint, freeze):
     command = [
@@ -113,19 +113,24 @@ class Snapshot:
         return parent_name, timestamp
 
     def get_full_volume(self):
-        return "{}/{}".format(self.volume_group, self.get_name())
+        return "{}/{}".format(self.parent_volume.volume_group, self.get_name())
 
     def get_mountpoint(self):
-        return os.path.join([
+        return os.path.join(
             SNAPSHOT_BASE_DIR, self.parent_volume.name, self.get_timestamp_str()
-        ])
+        )
+
+    def create_mountpoint(self):
+        os.makedirs(self.get_mountpoint(), mode=0o755, exist_ok=True)
 
     def get_mapper_device(self):
-        return "/dev/mapper/{}-{}".format(self.volume_group, self.get_name())
+        return "/dev/mapper/{}-{}".format(
+            self.parent_volume.volume_group,
+            self.get_name().replace("-", "--"))
 
     def create(self):
         parent_mountpoint = self.parent_volume.get_mountpoint()
-        with xfs_freeze(mountpoint):
+        with xfs_freeze(parent_mountpoint):
             create_command = [
                 "/sbin/lvcreate",
                 "--snapshot",
@@ -145,11 +150,12 @@ class Snapshot:
         ]
         sp.run(activate_command, check=True)
         self.active = True
+        self.create_mountpoint()
         mount_command = [
             "/bin/mount",
             self.get_mapper_device(),
             self.get_mountpoint(),
-            "-onouuid,ro" # nouuid is necessary for xfs snapshots
+            "-onouuid,ro,norecovery" # nouuid is necessary for xfs snapshots
         ]
         sp.run(mount_command, check=True)
 
@@ -175,6 +181,7 @@ class Snapshot:
         ]
         sp.run(deactivate_command, check=True)
         self.active = False
+        os.rmdir(self.get_mountpoint())
 
     @staticmethod
     def list_snapshots():
@@ -267,6 +274,7 @@ def load_config():
 
 def parse_config(config):
     periods = {}
+    min_interval = None
     for volume_conf in config["volume"]:
         name = volume_conf["name"]
         volume_group = volume_conf["volume_group"]
@@ -274,20 +282,27 @@ def parse_config(config):
         periods[volume] = []
         for raw_period in volume_conf["keep"]:
             interval = Period.parse_interval(raw_period["interval"])
+            if min_interval is None or interval < min_interval:
+                min_interval = interval
             number = int(raw_period["number"])
             periods[volume].append(
                 Period(target_number=number, interval=interval))
-    return periods
+    return periods, min_interval
 
-def mark_snapshots(snapshots, periods):
+def mark_snapshots(snapshots, periods, min_interval):
     all_snapshots = set(snapshots)
     marked_snapshots = set()
     budgets = {period: period.target_number for period in periods}
+    last_snapshot = {period: None for period in periods}
     for snapshot in sorted(snapshots, key=lambda s: s.timestamp):
-        for period in sorted(periods, key=Period.interval):
+        for period in sorted(periods, key=lambda p: p.interval):
+            required_distance = period.interval - min_interval/2
             if (budgets[period] > 0
                     and period.get_start() < snapshot.timestamp):
+                if (last_snapshot[period] is None
+                        or abs(snapshot.timestamp - last_snapshot[period].timestamp) > required_distance):
                     marked_snapshots.add(snapshot)
+                    last_snapshot[period] = snapshot
                     budgets[period] -= 1
     unmarked_snapshots = all_snapshots - marked_snapshots
     return unmarked_snapshots
@@ -295,15 +310,20 @@ def mark_snapshots(snapshots, periods):
 def main():
     config = load_config()
     snapshots = Snapshot.list_snapshots()
-    periods = parse_config(config)
+    periods, min_interval = parse_config(config)
     for volume in set(periods.keys()) - set(snapshots.keys()):
         print("Warning: Volume {} is configured but does not exist or has no snapshots.".format(volume))
     for volume in set(snapshots.keys()) - set(periods.keys()):
         print("Warning: Volume {} does exist but is not configured.".format(volume))
         snapshots.pop(volume)
     for volume in snapshots:
-        unmarked_snapshots = mark_snapshots(snapshots[volume], periods[volume])
-        print(unmarked_snapshots)
+        unmarked_snapshots = mark_snapshots(snapshots[volume], periods[volume], min_interval)
+        print("removing", unmarked_snapshots)
+        for snapshot in unmarked_snapshots:
+            snapshot.remove()
+        new_snapshot = Snapshot(volume, datetime.now())
+        new_snapshot.create()
+
 
 if __name__ == "__main__":
     main()