Source code for lago.utils

# Copyright 2014 Red Hat, Inc.
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
# Refer to the README and COPYING files for full details of the license
import Queue
import collections
import datetime
import fcntl
import functools
import json
import logging
import os
import shutil
import signal
import subprocess
import sys
import threading
import textwrap
import time
import yaml
from io import StringIO
import lockfile
import argparse
import configparser
import uuid as uuid_m
from . import constants
from .log_utils import (LogTask, setup_prefix_logging)
import hashlib

LOGGER = logging.getLogger(__name__)

[docs]class TimerException(Exception): """ Exception to throw when a timeout is reached """ pass
[docs]def _ret_via_queue(func, queue): try: queue.put({'return': func()}) except Exception: LOGGER.exception('Error while running thread') queue.put({'exception': sys.exc_info()})
[docs]def func_vector(target, args_sequence): return [functools.partial(target, *args) for args in args_sequence]
[docs]class VectorThread: def __init__(self, targets): self.targets = targets self.results = None
[docs] def start_all(self): self.thread_handles = [] for target in self.targets: q = Queue.Queue() t = threading.Thread(target=_ret_via_queue, args=(target, q)) self.thread_handles.append((t, q)) t.start()
[docs] def join_all(self, raise_exceptions=True): if self.results: return self.results for t, q in self.thread_handles: t.join() self.results = map(lambda (t, q): q.get(), self.thread_handles) if raise_exceptions: for result in self.results: if 'exception' in result: exc_info = result['exception'] raise exc_info[1], None, exc_info[2] return map(lambda x: x.get('return', None), self.results)
[docs]def invoke_in_parallel(func, *args_sequences): vt = VectorThread(func_vector(func, zip(*args_sequences))) vt.start_all() vt.join_all()
_CommandStatus = collections.namedtuple( 'CommandStatus', ('code', 'out', 'err') )
[docs]class CommandStatus(_CommandStatus): def __nonzero__(self): return self.code
[docs]def _run_command( command, input_data=None, stdin=None, out_pipe=subprocess.PIPE, err_pipe=subprocess.PIPE, env=None, uuid=None, **kwargs ): """ Runs a command Args: command(list of str): args of the command to execute, including the command itself as command[0] as `['ls', '-l']` input_data(str): If passed, will feed that data to the subprocess through stdin out_pipe(int or file): File descriptor as passed to :ref:subprocess.Popen to use as stdout stdin(int or file): File descriptor as passed to :ref:subprocess.Popen to use as stdin err_pipe(int or file): File descriptor as passed to :ref:subprocess.Popen to use as stderr env(dict of str:str): If set, will use the given dict as env for the subprocess uuid(uuid): If set the command will be logged with the given uuid converted to string, otherwise, a uuid v4 will be generated. **kwargs: Any other keyword args passed will be passed to the :ref:subprocess.Popen call Returns: lago.utils.CommandStatus: result of the interactive execution """ # add libexec to PATH if needed if uuid is None: uuid = uuid_m.uuid4() if constants.LIBEXEC_DIR not in os.environ['PATH'].split(':'): os.environ['PATH'] = '%s:%s' % ( constants.LIBEXEC_DIR, os.environ['PATH'] ) if input_data and not stdin: kwargs['stdin'] = subprocess.PIPE elif stdin: kwargs['stdin'] = stdin if env is None: env = os.environ.copy() else: env['PATH'] = ':'.join( list( set( env.get('PATH', '').split(':') + os.environ['PATH'] .split(':') ), ), ) popen = subprocess.Popen( ' '.join('"%s"' % arg for arg in command), stdout=out_pipe, stderr=err_pipe, shell=True, env=env, **kwargs ) out, err = popen.communicate(input_data) LOGGER.debug( '%s: command exit with return code: %d', str(uuid), popen.returncode ) if out: LOGGER.debug('%s: command stdout: %s', str(uuid), out) if err: LOGGER.debug('%s: command stderr: %s', str(uuid), err) return CommandStatus(popen.returncode, out, err)
[docs]def run_command( command, input_data=None, out_pipe=subprocess.PIPE, err_pipe=subprocess.PIPE, env=None, **kwargs ): """ Runs a command non-interactively Args: command(list of str): args of the command to execute, including the command itself as command[0] as `['ls', '-l']` input_data(str): If passed, will feed that data to the subprocess through stdin out_pipe(int or file): File descriptor as passed to :ref:subprocess.Popen to use as stdout err_pipe(int or file): File descriptor as passed to :ref:subprocess.Popen to use as stderr env(dict of str:str): If set, will use the given dict as env for the subprocess **kwargs: Any other keyword args passed will be passed to the :ref:subprocess.Popen call Returns: lago.utils.CommandStatus: result of the interactive execution """ if env is None: env = os.environ.copy() with LogTask( 'Run command: %s' % ' '.join('"%s"' % arg for arg in command), logger=LOGGER, level='debug', ) as task: command_result = _run_command( command=command, input_data=input_data, out_pipe=out_pipe, err_pipe=err_pipe, env=env, uuid=task.uuid, **kwargs ) return command_result
[docs]def run_interactive_command(command, env=None, **kwargs): """ Runs a command interactively, reusing the current stdin, stdout and stderr Args: command(list of str): args of the command to execute, including the command itself as command[0] as `['ls', '-l']` env(dict of str:str): If set, will use the given dict as env for the subprocess **kwargs: Any other keyword args passed will be passed to the :ref:subprocess.Popen call Returns: lago.utils.CommandStatus: result of the interactive execution """ command_result = _run_command( command=command, out_pipe=sys.stdout, err_pipe=sys.stderr, stdin=sys.stdin, env=env, **kwargs ) return command_result
[docs]def service_is_enabled(name): ret, out, _ = run_command(['systemctl', 'is-enabled', name]) if ret == 0 and out.strip() == 'enabled': return True return False
# Copied from VDSM: lib/vdsm/
[docs]class RollbackContext(object): ''' A context manager for recording and playing rollback. The first exception will be remembered and re-raised after rollback Sample usage: > with RollbackContext() as rollback: > step1() > rollback.prependDefer(lambda: undo step1) > def undoStep2(arg): pass > step2() > rollback.prependDefer(undoStep2, arg) More examples see tests/ @ vdsm code ''' def __init__(self, *args): self._finally = [] def __enter__(self): return self
[docs] def __exit__(self, exc_type, exc_value, traceback): """ If this function doesn't return True (or raises a different exception), python re-raises the original exception once this function is finished. """ undoExcInfo = None for undo, args, kwargs in self._finally: try: undo(*args, **kwargs) except Exception: # keep the earliest exception info if undoExcInfo is None: undoExcInfo = sys.exc_info() if exc_type is None and undoExcInfo is not None: raise undoExcInfo[0], undoExcInfo[1], undoExcInfo[2]
[docs] def defer(self, func, *args, **kwargs): self._finally.append((func, args, kwargs))
[docs] def prependDefer(self, func, *args, **kwargs): self._finally.insert(0, (func, args, kwargs))
[docs] def clear(self): self._finally = []
[docs]class EggTimer: def __init__(self, timeout): self.timeout = timeout def __enter__(self): self.start_time = time.time() return self def __exit__(self, *_): pass
[docs] def elapsed(self): return (time.time() - self.start_time) > self.timeout
[docs]class ExceptionTimer(object): def __init__(self, timeout): self.timeout = timeout or 0 def __enter__(self): self.start() def __exit__(self, *_): self.stop()
[docs] def start(self): def raise_timeout(*_): raise TimerException('Passed %d seconds' % self.timeout) signal.signal(signal.SIGALRM, raise_timeout) signal.alarm(self.timeout)
[docs] def stop(self): signal.alarm(0)
[docs]class LockFile(object): """ Context manager that creates a lock around a directory, with optional timeout in the acquire operation Args: path(str): path to the dir to lock timeout(int): timeout in seconds to wait while acquiring the lock **kwargs(dict): Any other param to pass to `lockfile.LockFile` """ def __init__(self, path, timeout=None, **kwargs): self.path = path self.timeout = timeout or 0 self.lock = lockfile.LockFile(path=path, **kwargs)
[docs] def __enter__(self): """ Start the lock with timeout if needed in the acquire operation Raises: TimerException: if the timeout is reached before acquiring the lock """ try: with ExceptionTimer(timeout=self.timeout): with LogTask('Acquiring lock for %s' % self.path): self.lock.acquire() except TimerException: raise TimerException( 'Unable to acquire lock for %s in %s secs', self.path, self.timeout, )
def __exit__(self, *_): self.lock.release()
[docs]def read_nonblocking(file_descriptor): oldfl = fcntl.fcntl(file_descriptor.fileno(), fcntl.F_GETFL) try: fcntl.fcntl( file_descriptor.fileno(), fcntl.F_SETFL, oldfl | os.O_NONBLOCK, ) return finally: fcntl.fcntl(file_descriptor.fileno(), fcntl.F_SETFL, oldfl)
[docs]def json_dump(obj, f): return json.dump(obj, f, indent=4)
[docs]def deepcopy(original_obj): """ Creates a deep copy of an object with no crossed referenced lists or dicts, useful when loading from yaml as anchors generate those cross-referenced dicts and lists Args: original_obj(object): Object to deep copy Return: object: deep copy of the object """ if isinstance(original_obj, list): return list(deepcopy(item) for item in original_obj) elif isinstance(original_obj, dict): return dict((key, deepcopy(val)) for key, val in original_obj.items()) else: return original_obj
[docs]def load_virt_stream(virt_fd): """ Loads the given conf stream into a dict, trying different formats if needed Args: virt_fd (str): file like objcect with the virt config to load Returns: dict: Loaded virt config """ try: virt_conf = json.load(virt_fd) except ValueError: virt_conf = yaml.load(virt_fd) return deepcopy(virt_conf)
[docs]def in_prefix(prefix_class, workdir_class): def decorator(func): @functools.wraps(func) def wrapper(*args, **kwargs): prefix_path = kwargs.get('prefix_path', None) workdir_path = kwargs.get('workdir_path', None) if ( prefix_path is not None or ( prefix_class.is_prefix(os.curdir) and workdir_path is None ) ): LOGGER.debug('Looking for a prefix') prefix_path = os.path.realpath( prefix_class.resolve_prefix_path(prefix_path) ) prefix = prefix_class(prefix_path) kwargs['parent_workdir'] = None else: LOGGER.debug('Looking for a workdir') if workdir_path is None: workdir_path = 'auto' workdir_path = workdir_class.resolve_workdir_path(workdir_path) workdir = workdir_class(path=workdir_path) kwargs['parent_workdir'] = workdir if kwargs.get('all_envs', False): prefix = workdir else: prefix_name = kwargs.get('prefix_name', 'current') prefix = workdir.get_prefix(prefix_name) kwargs['prefix_name'] = prefix_name prefix_path = os.path.realpath( os.path.join(workdir_path, prefix_name) ) kwargs['prefix'] = prefix os.environ['LAGO_PREFIX_PATH'] = prefix_path or '' os.environ['LAGO_WORKDIR_PATH'] = workdir_path or '' return func(*args, **kwargs) return wrapper return decorator
[docs]def with_logging(func): @functools.wraps(func) def wrapper(prefix, *args, **kwargs): setup_prefix_logging(prefix.paths.logs()) return func(*args, prefix=prefix, **kwargs) return wrapper
[docs]def add_timestamp_suffix(base_string): return datetime.datetime.fromtimestamp(time.time( )).strftime(base_string + '.%Y-%m-%d_%H:%M:%S')
[docs]def rotate_dir(base_dir): shutil.move(base_dir, add_timestamp_suffix(base_dir))
[docs]def ipv4_to_mac(ip): # Mac addrs of domains are 54:52:xx:xx:xx:xx where the last 4 octets are # the hex repr of the IP address) mac_addr_pieces = [0x54, 0x52] + [int(y) for y in ip.split('.')] return ':'.join([('%02x' % x) for x in mac_addr_pieces])
[docs]def argparse_to_ini(parser, root_section='lago', incl_unset=False): subparsers_actions = [ action for action in parser._actions if isinstance(action, argparse._SubParsersAction) ] root_actions = [ action for action in parser._actions if not isinstance(action, argparse._SubParsersAction) ] cp = configparser.ConfigParser(allow_no_value=True) _add_subparser_to_cp(cp, root_section, root_actions, incl_unset) for subparsers_action in subparsers_actions: for choice, subparser in subparsers_action.choices.items(): _add_subparser_to_cp(cp, choice, subparser._actions, incl_unset) header = '# Lago configuration file, generated: {0}'.format( time.strftime("%c") ) with StringIO() as ini_str: cp.write(ini_str) return '\n'.join([header, ini_str.getvalue()])
[docs]def _add_subparser_to_cp(cp, section, actions, incl_unset): cp.add_section(section) print_actions = ( action for action in actions if (action.default and action.default != '==SUPPRESS==' ) or (action.default is None and incl_unset) ) for action in print_actions: var = str(action.dest) if action.default is None: var = '#{0}'.format(var) if for line in textwrap.wrap(, width=70): cp.set(section, '# {0}'.format(line)) cp.set(section, var, str(action.default)) if len(cp.items(section)) == 0: cp.remove_section(section)
[docs]def run_command_with_validation( cmd, fail_on_error=True, msg='An error has occurred' ): result = run_command(cmd) if result and fail_on_error: raise RuntimeError('{}\n{}'.format(msg, result.err)) return result
[docs]def get_qemu_info(path, backing_chain=False, fail_on_error=True): """ Get info on a given qemu disk Args: path(str): Path to the required disk backing_chain(boo): if true, include also info about the image predecessors. Return: object: if backing_chain == True then a list of dicts else a dict """ cmd = ['qemu-img', 'info', '--output=json', path] if backing_chain: cmd.insert(-1, '--backing-chain') result = run_command_with_validation( cmd, fail_on_error, msg='Failed to get info for {}'.format(path) ) return json.loads(result.out)
[docs]def qemu_rebase(target, backing_file, safe=True, fail_on_error=True): """ changes the backing file of 'source' to 'backing_file' If backing_file is specified as "" (the empty string), then the image is rebased onto no backing file (i.e. it will exist independently of any backing file). (Taken from qemu-img man page) Args: target(str): Path to the source disk backing_file(str): path to the base disk safe(bool): if false, allow unsafe rebase (check qemu-img docs for more info) """ cmd = ['qemu-img', 'rebase', '-b', backing_file, target] if not safe: cmd.insert(2, '-u') return run_command_with_validation( cmd, fail_on_error, msg='Failed to rebase {target} onto {backing_file}'.format( target=target, backing_file=backing_file ) )
[docs]def compress(input_file, block_size, fail_on_error=True): cmd = [ 'xz', '--compress', '--keep', '--threads=0', '--best', '--force', '--verbose', '--block-size={}'.format(block_size), input_file ] return run_command_with_validation( cmd, fail_on_error, msg='Failed to compress {}'.format(input_file) )
[docs]def cp(input_file, output_file, fail_on_error=True): if not os.path.basename(output_file): output_file = os.path.join(output_file, os.path.basename(input_file)) cmd = ['cp', input_file, output_file] return run_command_with_validation( cmd, fail_on_error, msg='Failed to copy {} to {}'.format(input_file, output_file) )
[docs]def sparse(input_file, input_format, fail_on_error=True): cmd = [ 'virt-sparsify', '-q', '-v', '--format', input_format, '--in-place', input_file, ] return run_command_with_validation( cmd, fail_on_error, msg='Failed to sparse {}'.format(input_file) )
[docs]def get_hash(file_path, checksum='sha1'): """ Generate a hash for the given file Args: file_path (str): Path to the file to generate the hash for checksum (str): hash to apply, one of the supported by hashlib, for example sha1 or sha512 Returns: str: hash for that file """ sha = getattr(hashlib, checksum)() with open(file_path) as file_descriptor: while True: chunk = if not chunk: break sha.update(chunk) return sha.hexdigest()
[docs]def filter_spec(spec, paths, wildcard='*', separator='/'): """ Remove keys from a spec file. For example, with the following path: domains/*/disks/*/metadata all the metadata dicts from all domains disks will be removed. Args: spec (dict): spec to remove keys from paths (list): list of paths to the keys that should be removed wildcard (str): wildcard character separator (str): path separator Returns: None Raises: utils.LagoUserException: If a malformed path was detected """ def remove_key(path, spec): if len(path) == 0: return elif len(path) == 1: key = path.pop() if not isinstance(spec, collections.Mapping): raise LagoUserException( 'You have tried to remove the following key - "{key}".\n' 'Keys can not be removed from type {spec_type}\n' 'Please verify that path - "{{path}}" is valid'.format( key=key, spec_type=type(spec) ) ) if key == wildcard: spec.clear() else: spec.pop(key, None) else: current = path[0] if current == wildcard: if isinstance(spec, list): iterator = iter(spec) elif isinstance(spec, collections.Mapping): iterator = spec.itervalues() else: raise LagoUserException( 'Glob char {char} should refer only to dict or list, ' 'not to {spec_type}\n' 'Please fix path - "{{path}}"'.format( char=wildcard, spec_type=type(spec) ) ) for i in iterator: remove_key(path[1:], i) else: try: remove_key(path[1:], spec[current]) except KeyError: raise LagoUserException( 'Malformed path "{{path}}", key "{key}" ' 'does not exist'.format(key=current) ) except TypeError: raise LagoUserException( 'Malformed path "{{path}}", can not get ' 'by key from type {spec_type}'. format(spec_type=type(spec)) ) for path in paths: try: remove_key(path.split(separator), spec) except LagoUserException as e: e.message = e.message.format(path=path) raise
[docs]class LagoException(Exception): pass
[docs]class LagoUserException(LagoException): pass