django-orchestra/orchestra/utils/sys.py

203 lines
6.2 KiB
Python

import errno
import fcntl
import getpass
import os
import re
import select
import subprocess
import sys
from django.core.management.base import CommandError
def check_root(func):
""" Function decorator that checks if user has root permissions """
def wrapped(*args, **kwargs):
if getpass.getuser() != 'root':
cmd_name = func.__module__.split('.')[-1]
msg = "Sorry, '%s' must be executed as a superuser (root)"
raise CommandError(msg % cmd_name)
return func(*args, **kwargs)
return wrapped
def check_non_root(func):
""" Function decorator that checks if user not has root permissions """
def wrapped(*args, **kwargs):
if getpass.getuser() == 'root':
cmd_name = func.__module__.split('.')[-1]
raise CommandError("Sorry, you don't want to execute '%s' as superuser (root)." % cmd_name)
return func(*args, **kwargs)
return wrapped
class _Attribute(object):
""" Simple string subclass to allow arbitrary attribute access. """
def __init__(self, stdout):
self.stdout = stdout
def make_async(fd):
""" Helper function to add the O_NONBLOCK flag to a file descriptor """
fcntl.fcntl(fd, fcntl.F_SETFL, fcntl.fcntl(fd, fcntl.F_GETFL) | os.O_NONBLOCK)
def read_async(fd):
"""
Helper function to read some data from a file descriptor, ignoring EAGAIN errors
"""
try:
return fd.read()
except IOError as e:
if e.errno != errno.EAGAIN:
raise e
else:
return ''
def runiterator(command, display=False, stdin=b''):
""" Subprocess wrapper for running commands concurrently """
if display:
sys.stderr.write("\n\033[1m $ %s\033[0m\n" % command)
p = subprocess.Popen(command, shell=True, executable='/bin/bash',
stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE)
p.stdin.write(stdin)
p.stdin.close()
yield
make_async(p.stdout)
make_async(p.stderr)
# Async reading of stdout and sterr
while True:
stdout = b''
stderr = b''
# Get complete unicode chunks
select.select([p.stdout, p.stderr], [], [])
stdoutPiece = read_async(p.stdout)
stderrPiece = read_async(p.stderr)
stdout += (stdoutPiece or b'')
#.decode('ascii'), errors='replace')
stderr += (stderrPiece or b'')
#.decode('ascii'), errors='replace')
if display and stdout:
sys.stdout.write(stdout.decode('utf8'))
if display and stderr:
sys.stderr.write(stderr.decode('utf8'))
state = _Attribute(stdout)
state.stderr = stderr
state.return_code = p.poll()
state.command = command
yield state
if state.return_code != None:
p.stdout.close()
p.stderr.close()
raise StopIteration
def join(iterator, display=False, silent=False, error_codes=[0]):
""" joins the iterator process """
stdout = b''
stderr = b''
for state in iterator:
stdout += state.stdout
stderr += state.stderr
return_code = state.return_code
out = _Attribute(stdout.strip())
err = stderr.strip()
out.failed = False
out.return_code = return_code
out.stderr = err
if return_code not in error_codes:
out.failed = True
msg = "\nrun() encountered an error (return code %s) while executing '%s'\n"
msg = msg % (return_code, state.command)
if display:
sys.stderr.write("\n\033[1;31mCommandError: %s %s\033[m\n" % (msg, err))
if not silent:
raise CommandError("%s %s" % (msg, err))
out.succeeded = not out.failed
return out
def run(command, display=False, error_codes=[0], silent=False, stdin=b'', async=False):
iterator = runiterator(command, display, stdin)
next(iterator)
if async:
return iterator
return join(iterator, display=display, silent=silent, error_codes=error_codes)
def sshrun(addr, command, *args, **kwargs):
command = command.replace("'", """'"'"'""")
cmd = "ssh -o stricthostkeychecking=no -C root@%s '%s'" % (addr, command)
return run(cmd, *args, **kwargs)
def get_default_celeryd_username():
""" Introspect celeryd defaults file in order to get its username """
user = None
try:
with open('/etc/default/celeryd') as celeryd_defaults:
for line in celeryd_defaults.readlines():
if 'CELERYD_USER=' in line:
user = re.findall('"([^"]*)"', line)[0]
finally:
if user is None:
raise CommandError("Can not find the default celeryd username")
return user
def touch(fname, mode=0o666, dir_fd=None, **kwargs):
flags = os.O_CREAT | os.O_APPEND
with os.fdopen(os.open(fname, flags=flags, mode=mode, dir_fd=dir_fd)) as f:
os.utime(f.fileno() if os.utime in os.supports_fd else fname,
dir_fd=None if os.supports_fd else dir_fd, **kwargs)
class LockFile(object):
""" File-based lock mechanism used for preventing concurrency problems """
def __init__(self, lockfile, expire=5*60, unlocked=False):
""" /dev/shm/ can be a good place for storing locks ;) """
self.lockfile = lockfile
self.expire = expire
self.unlocked = unlocked
def acquire(self):
if os.path.exists(self.lockfile):
lock_time = os.path.getmtime(self.lockfile)
# lock expires to avoid starvation
if time.time()-lock_time < self.expire:
return False
touch(self.lockfile)
return True
def release(self):
os.remove(self.lockfile)
def __enter__(self):
if not self.unlocked:
if not self.acquire():
raise OperationLocked('%s lock file exists and its mtime is less '
'than %s seconds' % (self.lockfile, self.expire))
return True
def __exit__(self, type, value, traceback):
if not self.unlocked:
self.release()
def touch_wsgi():
from . import paths
run('{ sleep 2 && touch %s/wsgi.py; } &' % paths.get_project_dir(), async=True)