pre/post cmd tests

Add support for pre- and post-snapshot scripts (#39)

README.md

@@ -400,7 +400,7 @@ I'll add some tips when the issues start to get in on github. :)
 
 ## Transfer buffering, compression and rate limiting.
 
-If you're transferring over a slow link it might be useful to use `--compress=zstd-fast`. This will compres the data before sending, so it uses less bandwidth.
+If you're transferring over a slow link it might be useful to use `--compress=zstd-fast`. This will compress the data before sending, so it uses less bandwidth. An alternative to this is to use --zfs-compressed: This will transfer blocks that already have compression intact. (--compress will usually compress much better but uses much more resources. --zfs-compressed uses the least resources, but can be a disadvantage if you want to use a different compression method on the target.)
 
 You can also limit the datarate by using the `--rate` option.
 
@@ -417,6 +417,28 @@ zfs send -> send buffer -> custom send pipes -> compression -> transfer rate lim
 #### On the receiving side:
 decompression -> custom recv pipes -> buffer -> zfs recv
 
+## Running custom commands before and after snapshotting
+
+You can run commands before and after the snapshot to freeze databases to make the on for example to make the on-disk data consistent before snapshotting.
+
+The commands will be executed on the source side. Use the `--pre-snapshot-cmd` and `--post-snapshot-cmd` options for this.
+
+For example:
+
+```sh
+zfs-autobackup \
+    --pre-snapshot-cmd 'daemon -f jexec mysqljail1 mysql -s -e "set autocommit=0;flush logs;flush tables with read lock;\\! echo \$\$ > /tmp/mysql_lock.pid && sleep 60"' \
+    --pre-snapshot-cmd 'daemon -f jexec mysqljail2 mysql -s -e "set autocommit=0;flush logs;flush tables with read lock;\\! echo \$\$ > /tmp/mysql_lock.pid && sleep 60"' \
+    --post-snapshot-cmd 'pkill -F /jails/mysqljail1/tmp/mysql_lock.pid' \
+    --post-snapshot-cmd 'pkill -F /jails/mysqljail2/tmp/mysql_lock.pid' \
+    backupfs1
+```
+
+Failure handling during pre/post commands:
+
+* If a pre-command fails, zfs-autobackup will exit with an error. (after executing the post-commands)
+* All post-commands are always executed. Even if the pre-commands or actual snapshot have failed. This way you can be sure that stuff is always cleanedup and unfreezed.
+
 ## Tips
 
 * Use ```--debug``` if something goes wrong and you want to see the commands that are executed. This will also stop at the first error.
@@ -493,7 +515,8 @@ Look in man ssh_config for many more options.
 ```console
 usage: zfs-autobackup [-h] [--ssh-config CONFIG-FILE] [--ssh-source USER@HOST]
                       [--ssh-target USER@HOST] [--keep-source SCHEDULE]
-                      [--keep-target SCHEDULE] [--other-snapshots]
+                      [--keep-target SCHEDULE] [--pre-snapshot-cmd COMMAND]
+                      [--post-snapshot-cmd COMMAND] [--other-snapshots]
                       [--no-snapshot] [--no-send] [--no-thinning] [--no-holds]
                       [--min-change BYTES] [--allow-empty]
                       [--ignore-replicated] [--strip-path N]
@@ -531,6 +554,12 @@ optional arguments:
   --keep-target SCHEDULE
                         Thinning schedule for old target snapshots. Default:
                         10,1d1w,1w1m,1m1y
+  --pre-snapshot-cmd COMMAND
+                        Run COMMAND before snapshotting (can be used multiple
+                        times.
+  --post-snapshot-cmd COMMAND
+                        Run COMMAND after snapshotting (can be used multiple
+                        times.
   --other-snapshots     Send over other snapshots as well, not just the ones
                         created by this tool.
   --no-snapshot         Don't create new snapshots (useful for finishing

tests/test_zfsnode.py

@@ -1,6 +1,6 @@
 from basetest import *
 from zfs_autobackup.LogStub import LogStub
-
+from zfs_autobackup.ExecuteNode import ExecuteError
 
 
 class TestZfsNode(unittest2.TestCase):
@@ -9,7 +9,6 @@ class TestZfsNode(unittest2.TestCase):
         prepare_zpools()
         # return super().setUp()
 
-
     def test_consistent_snapshot(self):
         logger = LogStub()
         description = "[Source]"
@@ -33,7 +32,6 @@ test_source2/fs3/sub
 test_target1
 """)
 
-
         with self.subTest("second snapshot, no changes, no snapshot"):
             node.consistent_snapshot(node.selected_datasets(exclude_paths=[], exclude_received=False), "test-2", 1)
             r = shelltest("zfs list -H -o name -r -t all " + TEST_POOLS)
@@ -73,6 +71,59 @@ test_source2/fs3/sub
 test_target1
 """)
 
+    def test_consistent_snapshot_prepostcmds(self):
+        logger = LogStub()
+        description = "[Source]"
+        node = ZfsNode("test", logger, description=description, debug_output=True)
+
+        with self.subTest("Test if all cmds are executed correctly (no failures)"):
+            with OutputIO() as buf:
+                with redirect_stdout(buf):
+                    node.consistent_snapshot(node.selected_datasets(exclude_paths=[], exclude_received=False), "test-1",
+                                             0,
+                                             pre_snapshot_cmds=["echo pre1", "echo pre2"],
+                                             post_snapshot_cmds=["echo post1 >&2", "echo post2 >&2"]
+                                             )
+
+                self.assertIn("STDOUT > pre1", buf.getvalue())
+                self.assertIn("STDOUT > pre2", buf.getvalue())
+                self.assertIn("STDOUT > post1", buf.getvalue())
+                self.assertIn("STDOUT > post2", buf.getvalue())
+
+
+        with self.subTest("Failure in the middle, only pre1 and both post1 and post2 should be executed, no snapshot should be attempted"):
+            with OutputIO() as buf:
+                with redirect_stdout(buf):
+                    with self.assertRaises(ExecuteError):
+                        node.consistent_snapshot(node.selected_datasets(exclude_paths=[], exclude_received=False), "test-1",
+                                                 0,
+                                                 pre_snapshot_cmds=["echo pre1", "false", "echo pre2"],
+                                                 post_snapshot_cmds=["echo post1", "false", "echo post2"]
+                                                 )
+
+                print(buf.getvalue())
+                self.assertIn("STDOUT > pre1", buf.getvalue())
+                self.assertNotIn("STDOUT > pre2", buf.getvalue())
+                self.assertIn("STDOUT > post1", buf.getvalue())
+                self.assertIn("STDOUT > post2", buf.getvalue())
+
+        with self.subTest("Snapshot fails"):
+            with OutputIO() as buf:
+                with redirect_stdout(buf):
+                    with self.assertRaises(ExecuteError):
+                        #same snapshot name as before so it fails
+                        node.consistent_snapshot(node.selected_datasets(exclude_paths=[], exclude_received=False), "test-1",
+                                                 0,
+                                                 pre_snapshot_cmds=["echo pre1", "echo pre2"],
+                                                 post_snapshot_cmds=["echo post1", "echo post2"]
+                                                 )
+
+                print(buf.getvalue())
+                self.assertIn("STDOUT > pre1", buf.getvalue())
+                self.assertIn("STDOUT > pre2", buf.getvalue())
+                self.assertIn("STDOUT > post1", buf.getvalue())
+                self.assertIn("STDOUT > post2", buf.getvalue())
+
 
     def test_getselected(self):
         logger = LogStub()
@@ -92,13 +143,11 @@ test_target1
  (local): test_source1/fs1/sub,
  (local): test_source2/fs2/sub]""")
 
-
     def test_validcommand(self):
         logger = LogStub()
         description = "[Source]"
         node = ZfsNode("test", logger, description=description)
 
-
         with self.subTest("test invalid option"):
             self.assertFalse(node.valid_command(["zfs", "send", "--invalid-option", "nonexisting"]))
         with self.subTest("test valid option"):
@@ -111,7 +160,6 @@ test_target1
         # -D propably always supported
         self.assertGreater(len(node.supported_send_options), 0)
 
-
     def test_supportedrecvoptions(self):
         logger = LogStub()
         description = "[Source]"
@@ -120,6 +168,5 @@ test_target1
         self.assertIsInstance(node.supported_recv_options, list)
 
 
-
 if __name__ == '__main__':
     unittest.main()

zfs_autobackup/ZfsAutobackup.py

@@ -16,7 +16,7 @@ from zfs_autobackup.ThinnerRule import ThinnerRule
 class ZfsAutobackup:
     """main class"""
 
-    VERSION = "3.1-rc2"
+    VERSION = "3.1-rc4"
     HEADER = "zfs-autobackup v{} - (c)2021 E.H.Eefting (edwin@datux.nl)".format(VERSION)
 
     def __init__(self, argv, print_arguments=True):
@@ -45,6 +45,10 @@ class ZfsAutobackup:
                             help='Target ZFS filesystem (optional: if not specified, zfs-autobackup will only operate '
                                  'as snapshot-tool on source)')
 
+        parser.add_argument('--pre-snapshot-cmd', metavar="COMMAND", default=[], action='append',
+                            help='Run COMMAND before snapshotting (can be used multiple times.')
+        parser.add_argument('--post-snapshot-cmd', metavar="COMMAND", default=[], action='append',
+                            help='Run COMMAND after snapshotting (can be used multiple times.')
         parser.add_argument('--other-snapshots', action='store_true',
                             help='Send over other snapshots as well, not just the ones created by this tool.')
         parser.add_argument('--no-snapshot', action='store_true',
@@ -75,7 +79,7 @@ class ZfsAutobackup:
         parser.add_argument('--clear-mountpoint', action='store_true',
                             help='Set property canmount=noauto for new datasets. (recommended, prevents mount '
                                  'conflicts. same as --set-properties canmount=noauto)')
-        parser.add_argument('--filter-properties', metavar='PROPERY,...', type=str,
+        parser.add_argument('--filter-properties', metavar='PROPERTY,...', type=str,
                             help='List of properties to "filter" when receiving filesystems. (you can still restore '
                                  'them with zfs inherit -S)')
         parser.add_argument('--set-properties', metavar='PROPERTY=VALUE,...', type=str,
@@ -170,7 +174,7 @@ class ZfsAutobackup:
             self.warning("Using compression, but transfer is local.")
 
         if args.compress and args.zfs_compressed:
-            self.warning("Using --compress with --zfs-compress, might be inefficient.")
+            self.warning("Using --compress with --zfs-compressed, might be inefficient.")
 
     def verbose(self, txt):
         self.log.verbose(txt)
@@ -470,7 +474,7 @@ class ZfsAutobackup:
                                   ssh_to=self.args.ssh_source, readonly=self.args.test,
                                   debug_output=self.args.debug_output, description=description, thinner=source_thinner)
             source_node.verbose(
-                "Selects all datasets that have property 'autobackup:{}=true' (or childs of datasets that have "
+                "Selects all datasets that have property 'autobackup:{}=true' (or children of datasets that have "
                 "'autobackup:{}=child')".format(
                     self.args.backup_name, self.args.backup_name))
 
@@ -506,7 +510,9 @@ class ZfsAutobackup:
             if not self.args.no_snapshot:
                 self.set_title("Snapshotting")
                 source_node.consistent_snapshot(source_datasets, source_node.new_snapshotname(),
-                                                min_changed_bytes=self.args.min_change)
+                                                min_changed_bytes=self.args.min_change,
+                                                pre_snapshot_cmds=self.args.pre_snapshot_cmd,
+                                                post_snapshot_cmds=self.args.post_snapshot_cmd)
 
             ################# sync
             # if target is specified, we sync the datasets, otherwise we just thin the source. (e.g. snapshot mode)

zfs_autobackup/ZfsNode.py

@@ -1,6 +1,7 @@
 # python 2 compatibility
 from __future__ import print_function
 import re
+import shlex
 import subprocess
 import sys
 import time
@@ -161,7 +162,7 @@ class ZfsNode(ExecuteNode):
         """determine uniq new snapshotname"""
         return self.backup_name + "-" + time.strftime("%Y%m%d%H%M%S")
 
-    def consistent_snapshot(self, datasets, snapshot_name, min_changed_bytes):
+    def consistent_snapshot(self, datasets, snapshot_name, min_changed_bytes, pre_snapshot_cmds=[], post_snapshot_cmds=[]):
         """create a consistent (atomic) snapshot of specified datasets, per pool.
         """
 
@@ -191,6 +192,11 @@ class ZfsNode(ExecuteNode):
             self.verbose("No changes anywhere: not creating snapshots.")
             return
 
+        try:
+            for cmd in pre_snapshot_cmds:
+                self.verbose("Running pre-snapshot-cmd")
+                self.run(cmd=shlex.split(cmd), readonly=False)
+
             # create consistent snapshot per pool
             for (pool_name, snapshots) in pools.items():
                 cmd = ["zfs", "snapshot"]
@@ -200,8 +206,18 @@ class ZfsNode(ExecuteNode):
                 self.verbose("Creating snapshots {} in pool {}".format(snapshot_name, pool_name))
                 self.run(cmd, readonly=False)
 
+        finally:
+            for cmd in post_snapshot_cmds:
+                self.verbose("Running post-snapshot-cmd")
+                try:
+                    self.run(cmd=shlex.split(cmd), readonly=False)
+                except Exception as e:
+                    pass
+
+
+
     def selected_datasets(self, exclude_received, exclude_paths):
-        """determine filesystems that should be backupped by looking at the special autobackup-property, systemwide
+        """determine filesystems that should be backed up by looking at the special autobackup-property, systemwide
 
            returns: list of ZfsDataset
         """