btrfs: add new btrfs state

salt/states/btrfs.py

@@ -0,0 +1,258 @@
+# -*- coding: utf-8 -*-
+#
+# Author: Alberto Planas <aplanas@suse.com>
+#
+# Copyright 2018 SUSE LINUX GmbH, Nuernberg, Germany.
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+'''
+:maintainer:    Alberto Planas <aplanas@suse.com>
+:maturity:      new
+:depends:       None
+:platform:      Linux
+'''
+from __future__ import absolute_import, print_function, unicode_literals
+import functools
+import logging
+import os.path
+import tempfile
+import traceback
+
+from salt.exceptions import CommandExecutionError
+
+log = logging.getLogger(__name__)
+
+__virtualname__ = 'btrfs'
+
+
+def _mount(device):
+    '''
+    Mount the device in a temporary place.
+    '''
+    dest = tempfile.mkdtemp()
+    res = __states__['mount.mounted'](dest, device=device, fstype='btrfs',
+                                      opts='subvol=/', persist=False)
+    if not res['result']:
+        log.error('Cannot mount device %s in %s', device, dest)
+        _umount(dest)
+        return None
+    return dest
+
+
+def _umount(path):
+    '''
+    Umount and clean the temporary place.
+    '''
+    __states__['mount.unmounted'](path)
+    __utils__['files.rm_rf'](path)
+
+
+def _is_default(path, dest, name):
+    '''
+    Check if the subvolume is the current default.
+    '''
+    subvol_id = __salt__['btrfs.subvolume_show'](path)[name]['subvolume id']
+    def_id = __salt__['btrfs.subvolume_get_default'](dest)['id']
+    return subvol_id == def_id
+
+
+def _set_default(path, dest, name):
+    '''
+    Set the subvolume as the current default.
+    '''
+    subvol_id = __salt__['btrfs.subvolume_show'](path)[name]['subvolume id']
+    return __salt__['btrfs.subvolume_set_default'](subvol_id, dest)
+
+
+def _is_cow(path):
+    '''
+    Check if the subvolume is copy on write
+    '''
+    dirname = os.path.dirname(path)
+    return 'C' not in __salt__['file.lsattr'](dirname)[path]
+
+
+def _unset_cow(path):
+    '''
+    Disable the copy on write in a subvolume
+    '''
+    return __salt__['file.chattr'](path, operator='add', attributes='C')
+
+
+def __mount_device(action):
+    '''
+    Small decorator to makes sure that the mount and umount happends in
+    a transactional way.
+    '''
+    @functools.wraps(action)
+    def wrapper(*args, **kwargs):
+        name = kwargs['name']
+        device = kwargs['device']
+
+        ret = {
+            'name': name,
+            'result': False,
+            'changes': {},
+            'comment': ['Some error happends during the operation.'],
+        }
+        try:
+            dest = _mount(device)
+            if not dest:
+                msg = 'Device {} cannot be mounted'.format(device)
+                ret['comment'].append(msg)
+            kwargs['__dest'] = dest
+            ret = action(*args, **kwargs)
+        except Exception as e:
+            log.error('''Traceback: {}'''.format(traceback.format_exc()))
+            ret['comment'].append(e)
+        finally:
+            _umount(dest)
+        return ret
+    return wrapper
+
+
+@__mount_device
+def subvolume_created(name, device, qgroupids=None, set_default=False,
+                      copy_on_write=True, force_set_default=True,
+                      __dest=None):
+    '''
+    Makes sure that a btrfs subvolume is present.
+
+    name
+        Name of the subvolume to add
+
+    device
+        Device where to create the subvolume
+
+    qgroupids
+         Add the newly created subcolume to a qgroup. This parameter
+         is a list
+
+    set_default
+        If True, this new subvolume will be set as default when
+        mounted, unless subvol option in mount is used
+
+    copy_on_write
+        If false, set the subvolume with chattr +C
+
+    force_set_default
+        If false and the subvolume is already present, it will not
+        force it as default if ``set_default`` is True
+
+    '''
+    ret = {
+        'name': name,
+        'result': False,
+        'changes': {},
+        'comment': [],
+    }
+    path = os.path.join(__dest, name)
+
+    exists = __salt__['btrfs.subvolume_exists'](path)
+    if exists:
+        ret['comment'].append('Subvolume {} already present'.format(name))
+
+    # Resolve first the test case. The check is not complete, but at
+    # least we will report if a subvolume needs to be created. Can
+    # happend that the subvolume is there, but we also need to set it
+    # as default, or persist in fstab.
+    if __opts__['test']:
+        ret['result'] = None
+        if not exists:
+            ret['comment'].append('Subvolume {} will be created'.format(name))
+        return ret
+
+    if not exists:
+        # Create the directories where the subvolume lives
+        _path = os.path.dirname(path)
+        res = __states__['file.directory'](_path, makedirs=True)
+        if not res['result']:
+            ret['comment'].append('Error creating {} directory'.format(_path))
+            return ret
+
+        try:
+            __salt__['btrfs.subvolume_create'](name, dest=__dest,
+                                               qgroupids=qgroupids)
+        except CommandExecutionError:
+            ret['comment'].append('Error creating subvolume {}'.format(name))
+            return ret
+
+        ret['changes'][name] = 'Created subvolume {}'.format(name)
+
+    # If the volume was already present, we can opt-out the check for
+    # default subvolume.
+    if (not exists or (exists and force_set_default)) and \
+       set_default and not _is_default(path, __dest, name):
+        ret['changes'][name + '_default'] = _set_default(path, __dest, name)
+
+    if not copy_on_write and _is_cow(path):
+        ret['changes'][name + '_no_cow'] = _unset_cow(path)
+
+    ret['result'] = True
+    return ret
+
+
+@__mount_device
+def subvolume_deleted(name, device, commit=False, __dest=None):
+    '''
+    Makes sure that a btrfs subvolume is removed.
+
+    name
+        Name of the subvolume to remove
+
+    device
+        Device where to remove the subvolume
+
+    commit
+        Wait until the transaction is over
+
+    '''
+    ret = {
+        'name': name,
+        'result': False,
+        'changes': {},
+        'comment': [],
+    }
+
+    path = os.path.join(__dest, name)
+
+    exists = __salt__['btrfs.subvolume_exists'](path)
+    if not exists:
+        ret['comment'].append('Subvolume {} already missing'.format(name))
+
+    if __opts__['test']:
+        ret['result'] = None
+        if exists:
+            ret['comment'].append('Subvolume {} will be removed'.format(name))
+        return ret
+
+    # If commit is set, we wait until all is over
+    commit = 'after' if commit else None
+
+    if not exists:
+        try:
+            __salt__['btrfs.subvolume_delete'](path, commit=commit)
+        except CommandExecutionError:
+            ret['comment'].append('Error removing subvolume {}'.format(name))
+            return ret
+
+        ret['changes'][name] = 'Removed subvolume {}'.format(name)
+
+    ret['result'] = True
+    return ret