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      1 # Copyright 2015 The Chromium Authors. All rights reserved.
      2 # Use of this source code is governed by a BSD-style license that can be
      3 # found in the LICENSE file.
      4 
      5 """This module provides some utilities used by LXC and its tools.
      6 """
      7 
      8 import common
      9 from autotest_lib.client.bin import utils
     10 from autotest_lib.client.common_lib import error
     11 from autotest_lib.client.common_lib.cros.network import interface
     12 
     13 
     14 def path_exists(path):
     15     """Check if path exists.
     16 
     17     If the process is not running with root user, os.path.exists may fail to
     18     check if a path owned by root user exists. This function uses command
     19     `test -e` to check if path exists.
     20 
     21     @param path: Path to check if it exists.
     22 
     23     @return: True if path exists, otherwise False.
     24     """
     25     try:
     26         utils.run('sudo test -e "%s"' % path)
     27         return True
     28     except error.CmdError:
     29         return False
     30 
     31 
     32 def get_host_ip():
     33     """Get the IP address of the host running containers on lxcbr*.
     34 
     35     This function gets the IP address on network interface lxcbr*. The
     36     assumption is that lxc uses the network interface started with "lxcbr".
     37 
     38     @return: IP address of the host running containers.
     39     """
     40     # The kernel publishes symlinks to various network devices in /sys.
     41     result = utils.run('ls /sys/class/net', ignore_status=True)
     42     # filter out empty strings
     43     interface_names = [x for x in result.stdout.split() if x]
     44 
     45     lxc_network = None
     46     for name in interface_names:
     47         if name.startswith('lxcbr'):
     48             lxc_network = name
     49             break
     50     if not lxc_network:
     51         raise error.ContainerError('Failed to find network interface used by '
     52                                    'lxc. All existing interfaces are: %s' %
     53                                    interface_names)
     54     netif = interface.Interface(lxc_network)
     55     return netif.ipv4_address
     56 
     57 def clone(lxc_path, src_name, new_path, dst_name, snapshot):
     58     """Clones a container.
     59 
     60     @param lxc_path: The LXC path of the source container.
     61     @param src_name: The name of the source container.
     62     @param new_path: The LXC path of the destination container.
     63     @param dst_name: The name of the destination container.
     64     @param snapshot: Whether or not to create a snapshot clone.
     65     """
     66     snapshot_arg = '-s' if snapshot else ''
     67     # overlayfs is the default clone backend storage. However it is not
     68     # supported in Ganeti yet. Use aufs as the alternative.
     69     aufs_arg = '-B aufs' if utils.is_vm() and snapshot else ''
     70     cmd = (('sudo lxc-clone --lxcpath {lxcpath} --newpath {newpath} '
     71             '--orig {orig} --new {new} {snapshot} {backing}')
     72            .format(
     73                lxcpath = lxc_path,
     74                newpath = new_path,
     75                orig = src_name,
     76                new = dst_name,
     77                snapshot = snapshot_arg,
     78                backing = aufs_arg
     79            ))
     80     utils.run(cmd)
     81 
     82 
     83 def cleanup_host_mount(host_dir):
     84     """Unmounts and removes the given host dir.
     85 
     86     @param host_dir: The host dir to unmount and remove.
     87     """
     88     try:
     89         utils.run('sudo umount "%s"' % host_dir)
     90     except error.CmdError:
     91         # Ignore errors.  Most likely this occurred because the host dir
     92         # was already unmounted.
     93         pass
     94     utils.run('sudo rm -r "%s"' % host_dir)
     95