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#!/usr/bin/env python3
import hashlib
import collections
import fcntl
import glob
import inspect
import os
import re
import subprocess
import sys
import guestfs
import pymongo
import settings
import kpov_util
from util import write_default_config
def get_prepare_disks(db, class_id, task_id):
prepare_disks_source = db.prepare_disks.find_one({'class_id': class_id, 'task_id': task_id})['source']
d = {}
exec(compile(prepare_disks_source, 'prepare_disks.py', 'exec'), globals(), d)
return d['prepare_disks']
def create_snapshot(class_id, task_id, student_id, disk_name, overwrite=True):
# add a hash to filename to allow multiple students using the same directory
snap_hash = hashlib.sha1((disk_name+class_id+task_id+student_id).encode()).hexdigest()[:4]
snap = '{}-{}-{}.{}'.format(
task_id, disk_name, snap_hash, settings.STUDENT_DISK_FORMAT)
backing = []
template = disk_name + '.' + settings.STUDENT_DISK_FORMAT
task_dir = os.path.join(student_id, class_id, task_id)
task_path = os.path.join(settings.STUDENT_DISK_PATH, task_dir)
if not os.path.exists(os.path.join(task_path)) or overwrite:
if settings.STUDENT_DISK_COW:
# don’t use backing files, just copy the template
# (requires a cow-capable filesystem)
subprocess.call(['cp', '--reflink=always', template, snap])
else:
# create task dir
os.makedirs(task_path, exist_ok=True)
# qemu-img create stores backing-file path as given, so link all
# backing images to task directory where target image will be
# generated
os.chdir(settings.DISK_TEMPLATE_PATH) # qemu-img info is saner when called from image directory
output = subprocess.check_output(
['qemu-img', 'info', '--backing-chain', template], universal_newlines=True)
for image in [template] + [m.group(1) for m in re.finditer(r'backing file: (.*)', output)]:
backing += [image]
dest = os.path.join(task_path, image)
if not os.path.exists(dest):
os.symlink(os.path.join(settings.DISK_TEMPLATE_PATH, image), dest)
# would be great if someone finds a way to avoid the stuff above
# make overlay image
os.chdir(task_path)
subprocess.call(['qemu-img', 'create',
'-f', settings.STUDENT_DISK_FORMAT,
'-b', template, snap])
return task_dir, snap, backing
if __name__ == '__main__':
if len(sys.argv) != 1:
print("Usage: {0}")
print("Create the pending disk images")
db = pymongo.MongoClient(settings.DB_URI).get_default_database()
all_computers = collections.defaultdict(list)
for computer in db.student_computers.find({"disk_urls": {"$exists": False}}):
all_computers[(computer['class_id'], computer['task_id'], computer['student_id'])] += [computer]
for (class_id, task_id, student_id), computers in all_computers.items():
# TODO check why we iterate over student_computers twice
l = db.student_computers.find_one({'class_id': class_id, 'task_id': task_id, 'student_id': student_id})
if l is None:
continue
print("Creating {}/{} for {}".format(class_id, task_id, student_id))
lock_file = os.path.join(settings.STUDENT_LOCKFILE_PATH,
'{0}-{1}-{2}.lock'.format(student_id, class_id, task_id))
lock_fp = open(lock_file, 'w')
try:
fcntl.lockf(lock_fp, fcntl.LOCK_EX | fcntl.LOCK_NB)
except IOError:
continue
task_params = db.task_params.find_one({'class_id': class_id, 'task_id': task_id, 'student_id': student_id})['params']
prepare_disks = get_prepare_disks(db, class_id, task_id)
# tule odpri, ustvari snapshote za vajo
templates = {}
all_disks = collections.defaultdict(list)
parts = {}
for computer in computers:
lock_fp.write('creating computer ' + computer['name'] + '\n')
if len(computer['disks']) == 0:
continue
manual_disks = []
try_automount = False
g = guestfs.GuestFS()
for disk in computer['disks']:
lock_fp.write("register " + disk['name'] + '\n')
task_dir, snap, backing = create_snapshot(class_id, task_id, student_id, disk['name'])
snap_file = os.path.join(settings.STUDENT_DISK_PATH, task_dir, snap)
if 'options' in disk:
g.add_drive_opts(snap_file, **(disk['options']))
else:
g.add_drive(snap_file)
if 'parts' in disk:
for p in disk['parts']:
lock_fp.write("part {}: {}\n".format(
settings.GUESTFS_DEV_PREFIX + p['dev'], p['path']))
manual_disks.append(
(settings.GUESTFS_DEV_PREFIX + p['dev'], p['path'], p.get('options', None)))
else:
try_automount = True
templates[disk['name']] = g
lock_fp.write(" templates[{}] = {}\n".format(disk['name'], disk))
all_disks[computer['name']] += [{
'name': disk['name'],
'file': snap,
'backing': backing,
}]
g.launch()
mounted = set()
if try_automount:
roots = g.inspect_os()
for root in roots:
mps = g.inspect_get_mountpoints(root)
lock_fp.write('detected: ' + str(mps) + '\n')
for mountpoint, device in sorted(mps):
if mountpoint not in mounted:
try:
g.mount(device, mountpoint, )
lock_fp.write( 'mounted ' + device + ' on ' + mountpoint + '\n')
except RuntimeError as msg:
lock_fp.write( "%s (ignored)\n" % msg)
mounted.add(mountpoint)
for device, mountpoint, opts in manual_disks:
try:
if opts is not None:
g.mount_options(opts, device, mountpoint)
else:
g.mount(device, mountpoint)
lock_fp.write('manually mounted ' + device + " on " + mountpoint + '\n')
except RuntimeError as msg:
lock_fp.write( "%s (ignored)\n" % msg)
lock_fp.write("preparing disks\n")
global_params = {
'task_name': task_id,
'class_id': class_id,
'username': student_id
}
if 'TASK_URL' in vars(settings):
global_params['task_url'] = settings.TASK_URL + '/' + class_id + '/'
prepare_disks(templates, task_params, global_params)
# pospravi za seboj.
lock_fp.write("unmounting\n")
for g in set(templates.values()):
g.umount_all()
g.close()
lock_fp.write("saving URLs\n")
for computer in computers:
comp_name = computer['name']
disks = all_disks[comp_name]
lock_fp.write('urls: '+ str(disks) + '\n')
l = db.student_computers.update({
'disk_urls': {'$exists': False},
'student_id': student_id,
'task_id': task_id,
'class_id': class_id,
'name': comp_name},
{'$set': { 'disk_urls': disks }
})
os.unlink(lock_file)
lock_fp.close()
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