charm-swift-storage/lib/misc_utils.py

from charmhelpers.contrib.storage.linux.utils import (
    is_block_device,
    zap_disk,
)

from charmhelpers.contrib.storage.linux.loopback import (
    ensure_loopback_device,
)

from charmhelpers.contrib.storage.linux.lvm import (
    deactivate_lvm_volume_group,
    is_lvm_physical_volume,
    remove_lvm_physical_volume,
)

from charmhelpers.core.host import (
    mounts,
    umount,
    restart_on_change,
)

from charmhelpers.core.hookenv import (
    log,
    INFO,
    ERROR,
    status_get,
    status_set,
)

DEFAULT_LOOPBACK_SIZE = '5G'


def ensure_block_device(block_device):
    '''
    Confirm block_device, create as loopback if necessary.

    :param block_device: str: Full path of block device to ensure.

    :returns: str: Full path of ensured block device.
    '''
    _none = ['None', 'none', None]
    if (block_device in _none):
        log('prepare_storage(): Missing required input: '
            'block_device=%s.' % block_device, level=ERROR)
        raise

    if block_device.startswith('/dev/'):
        bdev = block_device
    elif block_device.startswith('/'):
        _bd = block_device.split('|')
        if len(_bd) == 2:
            bdev, size = _bd
        else:
            bdev = block_device
            size = DEFAULT_LOOPBACK_SIZE
        bdev = ensure_loopback_device(bdev, size)
    else:
        bdev = '/dev/%s' % block_device

    if not is_block_device(bdev):
        log('Failed to locate valid block device at %s' % bdev, level=ERROR)
        # ignore missing block devices
        return

    return bdev


def clean_storage(block_device):
    '''
    Ensures a block device is clean.  That is:
        - unmounted
        - any lvm volume groups are deactivated
        - any lvm physical device signatures removed
        - partition table wiped

    :param block_device: str: Full path to block device to clean.
    '''
    for mp, d in mounts():
        if d == block_device:
            log('clean_storage(): Found %s mounted @ %s, unmounting.' %
                (d, mp), level=INFO)
            umount(mp, persist=True)

    if is_lvm_physical_volume(block_device):
        deactivate_lvm_volume_group(block_device)
        remove_lvm_physical_volume(block_device)
    else:
        zap_disk(block_device)


def is_paused(status_get=status_get):
    """Is the unit paused?"""
    status, message = status_get()
    return status == "maintenance" and message.startswith("Paused")


def pause_aware_restart_on_change(restart_map):
    """Avoids restarting services if config changes when unit is paused."""
    def wrapper(f):
        if is_paused():
            # save/restore paused status in case called function changes it
            status, message = status_get()
            ret = f
            status_set(status, message)
            return ret
        else:
            return restart_on_change(restart_map)(f)
    return wrapper