growpart/rootgrow

#!/usr/bin/python3
import os
import re
import syslog

split_dev = re.compile('([a-z/]*)(\d*)')
mounts = open('/proc/mounts' ,'r').readlines()

def get_mount_point(device):
    for mount in mounts:
        if mount.startswith(device):
            return mount.split(' ')[1]

def is_mount_read_only(mountpoint):
    for mount in mounts:
        mount_values = mount.split(' ')
        if mount_values[1] == mountpoint:
            mount_opts = mount_values[3].split(',')
            return 'ro' in mount_opts

def resize_fs(fs_type, device):
    if fs_type.startswith('ext'):
        cmd = 'resize2fs %s' % device
        syslog.syslog(
            syslog.LOG_INFO,
            'Resizing: "%s"' %cmd
        )
        os.system(cmd)
    elif fs_type == 'xfs':
        mnt_point = get_mount_point(device)
        cmd = 'xfs_growfs %s' % mnt_point
        syslog.syslog(
            syslog.LOG_INFO,
            'Resizing: "%s"' %cmd
        )
        os.system(cmd)
    elif fs_type == 'btrfs':
        mnt_point = get_mount_point(device)
        # If the volume is read-only, the resize operation will fail even
        # though it's still probably wanted to do the resize. A feasible
        # work-around is to use snapper's .snapshots subdir (if exists)
        # instead of the volume path for the resize operation.
        if is_mount_read_only(mnt_point):
            if os.path.isdir('{}/.snapshots'.format(mnt_point)):
                cmd = 'btrfs filesystem resize max {}/.snapshots'.format(
                    mnt_point)
            else:
                syslog.syslog(
                    syslog.LOG_ERR,
                    "cannot resize read-only btrfs without snapshots"
                )
                return
        else:
            cmd = 'btrfs filesystem resize max {}'.format(mnt_point)
        syslog.syslog(
            syslog.LOG_INFO,
            'Resizing: "%s"' %cmd
         )
        os.system(cmd)


for mount in mounts:
    if ' / ' in mount:
        mount_dev = mount.split(' ')[0]
        fs = mount.split(' ')[2]
        try:
            dev, partition = split_dev.match(mount_dev).groups()
        except:
            syslog.syslog(
                syslog.LOG_ERR,
                'match exception for "%s"' % mount
            )
            break
        if dev and partition:
            cmd = '/usr/sbin/growpart %s %s' %(dev, partition)
            syslog.syslog(
                syslog.LOG_INFO,
                'Executing: "%s"' % cmd
            )
            os.system(cmd)
            resize_fs(fs, mount_dev)
        else:
            syslog.syslog(
                syslog.LOG_ERR,
                'could not match device and partition in "%s"' % mount
            )