lxc-proxmox-noatime

#!/usr/bin/env python2
#
# lxc.hook.pre-start
#
# remounts proxmox container mounts with noatime for performance
# 
# copy this file to /usr/share/lxc/hooks/lxc-proxmox-noatime
# create /usr/share/lxc/config/common.conf.d/99-mount-noatime.conf
# with contents: lxc.hook.pre-mount /usr/share/lxc/hooks/lxc-proxmox-noatime

import argparse
import ctypes
import ctypes.util
import os
import platform
import psutil
import sys

import logging
import logging.handlers
from logging.handlers import SysLogHandler


MS_MGC_VAL = 0xc0ed0000  # Magic flag number to indicate "new" flags
MS_NOATIME = 1024
MS_REMOUNT = 32

libc = ctypes.CDLL(ctypes.util.find_library('c'), use_errno=True)
libc.mount.argtypes = (ctypes.c_char_p, ctypes.c_char_p, ctypes.c_char_p, ctypes.c_ulong, ctypes.c_char_p)

rootfs = os.environ['LXC_ROOTFS_PATH']

if 'LXC_NAME' in os.environ:
    hostname = os.environ['LXC_NAME']
else:
    hostname = platform.node().split('.')[0]

logger = logging.getLogger(os.path.basename(sys.argv[0]))
logger.setLevel(logging.DEBUG)
syslog_handler = SysLogHandler(
    address='/dev/log',
    facility=SysLogHandler.LOG_DAEMON
)
syslog_handler.setFormatter(
    logging.Formatter('%(name)s: vmid={0} %(message)s'.format(hostname))
)
logger.addHandler(syslog_handler)


def parse_arguments():
    parser = argparse.ArgumentParser(description='NMI mount pre-start container hooks')
    parser.add_argument('vmid',
                        help='container name', type=str)
    parser.add_argument('section',
                        help='always "lxc"', type=str)
    parser.add_argument('type',
                        help='hook type', type=str)

    return parser.parse_args()


def remount_noatime(source, target, fs):
    ret = libc.mount(source, target, fs, MS_REMOUNT | MS_NOATIME, '')
    if ret < 0:
        errno = ctypes.get_errno()
        raise OSError(errno, "Error remounting {} with noatime: {}".
                      format(target, os.strerror(errno)))


if __name__ == '__main__':
    try:
        args = parse_arguments()
        partitions = psutil.disk_partitions()
        for p in partitions:
            if p.mountpoint.startswith(rootfs):
                logger.info('remounting {0} with noatime'.format(p.mountpoint))
                remount_noatime(p.device, p.mountpoint, p.fstype)

    except Exception:
        logger.exception('failed to pre-start mounts')