Merge pull request #18513 from ceph/ceph-volume-zap

ceph-volume: adds the ceph-volume lvm zap subcommand

Reviewed-by: Alfredo Deza <adeza@redhat.com>

doc/ceph-volume/index.rst

@@ -30,3 +30,4 @@ technologies, including plain disks.
    lvm/scan
    lvm/systemd
    lvm/list
+   lvm/zap

doc/ceph-volume/lvm/zap.rst

@@ -0,0 +1,19 @@
+.. _ceph-volume-lvm-zap:
+
+``zap``
+=======
+
+This subcommand is used to zap lvs or partitions that have been used
+by ceph OSDs so that they may be reused. If given a path to a logical
+volume it must be in the format of vg/lv. Any filesystems present
+on the given lv or partition will be removed and all data will be purged.
+
+.. note:: The lv or partition will be kept intact.
+
+Zapping a logical volume::
+
+      ceph-volume lvm zap {vg name/lv name}
+
+Zapping a partition::
+
+      ceph-volume lvm zap /dev/sdc1

src/ceph-volume/ceph_volume/api/lvm.py

@@ -213,6 +213,29 @@ def create_vg(name, *devices):
     return vg
 
 
+def remove_lv(path):
+    """
+    Removes a logical volume given it's absolute path.
+
+    Will return True if the lv is successfully removed or
+    raises a RuntimeError if the removal fails.
+    """
+    stdout, stderr, returncode = process.call(
+        [
+            'sudo',
+            'lvremove',
+            '-v',  # verbose
+            '-f',  # force it
+            path
+        ],
+        show_command=True,
+        terminal_verbose=True,
+    )
+    if returncode != 0:
+        raise RuntimeError("Unable to remove %s".format(path))
+    return True
+
+
 def create_lv(name, group, size=None, tags=None):
     """
     Create a Logical Volume in a Volume Group. Command looks like::
@@ -629,6 +652,14 @@ class Volume(object):
         obj['path'] = self.lv_path
         return obj
 
+    def clear_tags(self):
+        """
+        Removes all tags from the Logical Volume.
+        """
+        for k, v in self.tags.items():
+            tag = "%s=%s" % (k, v)
+            process.run(['sudo', 'lvchange', '--deltag', tag, self.lv_path])
+
     def set_tags(self, tags):
         """
         :param tags: A dictionary of tag names and values, like::

src/ceph-volume/ceph_volume/devices/lvm/main.py

@@ -6,6 +6,7 @@ from . import prepare
 from . import create
 from . import trigger
 from . import listing
+from . import zap
 
 
 class LVM(object):
@@ -24,6 +25,7 @@ class LVM(object):
         'create': create.Create,
         'trigger': trigger.Trigger,
         'list': listing.List,
+        'zap': zap.Zap,
     }
 
     def __init__(self, argv):

src/ceph-volume/ceph_volume/devices/lvm/prepare.py

@@ -120,9 +120,13 @@ class Prepare(object):
             tags['ceph.%s_uuid' % device_type] = uuid
             tags['ceph.%s_device' % device_type] = path
             lv.set_tags(tags)
-            return path, uuid, tags
-        # otherwise assume this is a regular disk partition
-        return device_name, self.get_ptuuid(device_name), tags
+        else:
+            # otherwise assume this is a regular disk partition
+            uuid = self.get_ptuuid(device_name)
+            path = device_name
+            tags['ceph.%s_uuid' % device_type] = uuid
+            tags['ceph.%s_device' % device_type] = path
+        return path, uuid, tags
 
     @decorators.needs_root
     def prepare(self, args):

src/ceph-volume/ceph_volume/devices/lvm/zap.py

@@ -0,0 +1,107 @@
+import argparse
+import logging
+
+from textwrap import dedent
+
+from ceph_volume import decorators, terminal, process
+from ceph_volume.api import lvm as api
+
+logger = logging.getLogger(__name__)
+
+
+def wipefs(path):
+    """
+    Removes the filesystem from an lv or partition.
+    """
+    process.run([
+        'sudo',
+        'wipefs',
+        '--all',
+        path
+    ])
+
+
+def zap_data(path):
+    """
+    Clears all data from the given path. Path should be
+    an absolute path to an lv or partition.
+
+    10M of data is written to the path to make sure that
+    there is no trace left of any previous Filesystem.
+    """
+    process.run([
+        'dd',
+        'if=/dev/zero',
+        'of={path}'.format(path=path),
+        'bs=1M',
+        'count=10',
+    ])
+
+
+class Zap(object):
+
+    help = 'Removes all data and filesystems from a logical volume or partition.'
+
+    def __init__(self, argv):
+        self.argv = argv
+
+    @decorators.needs_root
+    def zap(self, args):
+        device = args.device
+        lv = api.get_lv_from_argument(device)
+        if lv:
+            # we are zapping a logical volume
+            path = lv.lv_path
+        else:
+            # we are zapping a partition
+            #TODO: ensure device is a partition
+            path = device
+
+        logger.info("Zapping: %s", path)
+        terminal.write("Zapping: %s" % path)
+
+        wipefs(path)
+        zap_data(path)
+
+        if lv:
+            # remove all lvm metadata
+            lv.clear_tags()
+
+        terminal.success("Zapping successful for: %s" % path)
+
+    def main(self):
+        sub_command_help = dedent("""
+        Zaps the given logical volume or partition. If given a path to a logical
+        volume it must be in the format of vg/lv. Any filesystems present
+        on the given lv or partition will be removed and all data will be purged.
+
+        However, the lv or partition will be kept intact.
+
+        Example calls for supported scenarios:
+
+          Zapping a logical volume:
+
+              ceph-volume lvm zap {vg name/lv name}
+
+          Zapping a partition:
+
+              ceph-volume lvm zap /dev/sdc1
+
+        """)
+        parser = argparse.ArgumentParser(
+            prog='ceph-volume lvm zap',
+            formatter_class=argparse.RawDescriptionHelpFormatter,
+            description=sub_command_help,
+        )
+
+        parser.add_argument(
+            'device',
+            metavar='DEVICE',
+            nargs='?',
+            help='Path to an lv (as vg/lv) or to a partition like /dev/sda1'
+        )
+        if len(self.argv) == 0:
+            print(sub_command_help)
+            return
+        args = parser.parse_args(self.argv)
+        self.zap(args)

src/ceph-volume/ceph_volume/tests/api/test_lvm.py

@@ -353,6 +353,22 @@ class TestGetLVFromArgument(object):
         assert api.get_lv_from_argument('/path/to/lv') == self.foo_volume
 
 
+class TestRemoveLV(object):
+
+    def test_removes_lv(self, monkeypatch):
+        def mock_call(cmd, **kw):
+            return ('', '', 0)
+        monkeypatch.setattr(process, 'call', mock_call)
+        assert api.remove_lv("vg/lv")
+
+    def test_fails_to_remove_lv(self, monkeypatch):
+        def mock_call(cmd, **kw):
+            return ('', '', 1)
+        monkeypatch.setattr(process, 'call', mock_call)
+        with pytest.raises(RuntimeError):
+            api.remove_lv("vg/lv")
+
+
 class TestCreateLV(object):
 
     def setup(self):

src/ceph-volume/ceph_volume/tests/devices/test_zap.py

@@ -0,0 +1,17 @@
+import pytest
+from ceph_volume.devices import lvm
+
+
+class TestZap(object):
+
+    def test_main_spits_help_with_no_arguments(self, capsys):
+        lvm.zap.Zap([]).main()
+        stdout, stderr = capsys.readouterr()
+        assert 'Zaps the given logical volume or partition' in stdout
+
+    def test_main_shows_full_help(self, capsys):
+        with pytest.raises(SystemExit):
+            lvm.zap.Zap(argv=['--help']).main()
+        stdout, stderr = capsys.readouterr()
+        assert 'optional arguments' in stdout
+        assert 'positional arguments' in stdout