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Editing: lvestats_server.py
# -*- coding: utf-8 -*- # # Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2019 All Rights Reserved # # Licensed under CLOUD LINUX LICENSE AGREEMENT # http://cloudlinux.com/docs/LICENSE.TXT import io import logging import os import signal import sys import time import traceback import psutil from lvestats.lib.commons.func import reboot_lock from lvestats.lib import config, dbengine from lvestats.lib.commons.func import LVEVersionError, get_lve_version from lvestats.lib.commons.logsetup import setup_logging DEV_NULL = '/dev/null' PIDFILE = "" class EnvironmentException(Exception): def __init__(self, message): super().__init__() self.message = message def get_process_pid(): """ Check if lvestats already running :return int|None: None - if no process found; pid - if some lvestats-server found """ if PIDFILE and os.path.isfile(PIDFILE): try: with open(PIDFILE, 'r', encoding='utf-8') as f: pid = int(f.read().strip()) os.kill(pid, 0) # try to send some return pid except (IOError, OSError): return None # No pidfile or no process found def stop_server(): exit_code = 0 def kill_process(_pid: int, _signal: signal.Signals): """Kill process by pid by sending a specific signal to it""" try: os.kill(_pid, _signal) except (OSError, ProcessLookupError): log.info("Process with pid '%d' is already dead", _pid) def on_sigusr2(_proc: psutil.Process): """callback for psutil.wait_procs()""" log.info("Signal 'SIGUSR2' sent to child process: %s", _proc) def on_terminate(_proc: psutil.Process): """callback for psutil.wait_procs()""" log.info("Signal 'SIGTERM' sent to child process: %s", _proc) log = setup_logging({}, caller_name='stop_server') pid = get_process_pid() if pid is None: exit_code = 1 else: process = psutil.Process(pid) childs = process.children(recursive=True) with reboot_lock(timeout=60 * 10): for child in childs: # There may be stored absent childs, so we need to kill # only existing processes if psutil.pid_exists(child.pid): kill_process(child.pid, signal.SIGUSR2) _, alive = psutil.wait_procs(childs, timeout=3, callback=on_sigusr2) for p in alive: kill_process(p.pid, signal.SIGTERM) _, alive = psutil.wait_procs(childs, timeout=3, callback=on_terminate) kill_process(pid, signal.SIGTERM) time.sleep(0.15) for child in alive: kill_process(child.pid, signal.SIGKILL) return exit_code def setup_default_exception_hook(): def hook(_type, _ex, _trace): sio = io.StringIO() traceback.print_tb(_trace, file=sio) msg = f"Uncaught exception {_type}\nmessage='%s'\n:%s" logging.error(msg, str(_ex), sio.getvalue()) sio.close() sys.__excepthook__(_type, _ex, _trace) sys.excepthook = hook def run_main(cnf, singleprocess, plugins, profiling_log, times_): from lvestats import main # pylint: disable=import-outside-toplevel,redefined-outer-name main.main(cnf, singleprocess, plugins, profiling_log, times_) def sigterm_handler(signum, frame): log = logging.getLogger('sigterm_handler') log.info('SIGTERM handler. Shutting Down.') os._exit(0) def _check_db_connection(cnf, log_): """ Check whether database connection can be established and db schema is ok. Raises exception if database is broken. :type cnf: dict :type log_: logging.Logger :raises: EnvironmentException """ log_.debug('Check for running SQL server') try: engine = dbengine.make_db_engine(cnf) engine.execute("SELECT 1;") validation = dbengine.validate_database(engine) if validation['column_error'] or validation['table_error']: sys.exit(1) except Exception as ex: msg = "Error occurred during connecting to SQL server:" log_.fatal(str(ex)) log_.exception(ex) raise EnvironmentException(f"\n{msg}\n{ex}\n") from ex def _check_valid_lve_version(log_): """ Check for possible misconfiguration if cpu speed is reported as 0 with /proc/cpuinfo and lve version <= 4. Raises exception, if so. :type log_: logging.Logger :raises: EnvironmentException """ log_.debug('Check for valid LVE version') lve_version = get_lve_version() if lve_version <= 4: msg = "LVE version <= 4" log_.fatal('LVE version <= 4. Please, update.') raise EnvironmentException(f"\n{msg}\n") def _check_running_process(log_): """ Check if another instance of lve-stats is already running. Raises exception, if so. :param log_: logging.Logger :raises: EnvironmentException """ log_.debug('Check for running lvestats-server') rc = get_process_pid() if rc: msg = f"Lvestats-server already running with pid {rc}. Exiting" log_.warning(msg) raise EnvironmentException(msg) def _is_environment_ok(cnf, log_): """ Checks whether system environment works fine. Return True if ok, False otherwise. :type cnf: dict :type log_: logging.Logger :rtype: bool """ try: _check_running_process(log_) _check_db_connection(cnf, log_) _check_valid_lve_version(log_) except EnvironmentException as ex: sys.stderr.write(ex.message) sys.stderr.flush() return False return True def daemonize(cnf, singleprocess, plugins, profiling_log, times): def fork(): try: return os.fork() except OSError as e: raise RuntimeError(f"{e.strerror} [{e.errno}]") from e setup_logging(cnf, console_level=logging.CRITICAL) setup_default_exception_hook() log_ = logging.getLogger('server') # check for issues with environment if not _is_environment_ok(cnf, log_): sys.exit(1) log_.debug('Starting server') pid = fork() if pid: log_.debug('First fork, pid=%d', pid) time.sleep(0.2) os._exit(0) os.setsid() signal.signal(signal.SIGTERM, sigterm_handler) pid = fork() if pid: log_.debug('Second fork, pid=%d', pid) if PIDFILE: log_.debug('Writing pid to file %s', PIDFILE) with open(PIDFILE, 'w', encoding='utf-8') as pidfile: pidfile.write(str(pid)) # exit parent process log_.debug('Child daemon fork ok') os._exit(0) os.nice(10) os.setpgrp() os.chdir('/') previous_umask = os.umask(0) sys.stdout.flush() sys.stderr.flush() # pylint: disable=consider-using-with,unspecified-encoding si = open(DEV_NULL, 'r') so = open(DEV_NULL, 'a+') # read + write allowed se = open(DEV_NULL, 'a+') # read + write allowed # pylint: enable=consider-using-with,unspecified-encoding os.dup2(si.fileno(), sys.stdin.fileno()) os.dup2(so.fileno(), sys.stdout.fileno()) os.dup2(se.fileno(), sys.stderr.fileno()) log_.info('Starting main() in daemon') os.umask(previous_umask) run_main(cnf, singleprocess, plugins, profiling_log, times) def process_opts(cnf, _opts, _times): if _opts.action == 'stop': sys.exit(stop_server()) elif _opts.action == 'restart': # stop and start stop_server() daemonize(cnf, _opts.singleprocess, _opts.plugins, _opts.profiling_log, _times) elif _opts.action == 'start': if _opts.nodaemon: debug_mode = logging.DEBUG if _opts.debug_mode else logging.INFO setup_logging(cnf, console_level=debug_mode, file_level=debug_mode) setup_default_exception_hook() run_main(cnf, _opts.singleprocess, _opts.plugins, _opts.profiling_log, _times) else: daemonize(cnf, _opts.singleprocess, _opts.plugins, _opts.profiling_log, _times) def main(opts): if not opts.pidfile: print("--pidfile should be specified") sys.exit(1) else: global PIDFILE PIDFILE = opts.pidfile times = None if opts.times: times = int(opts.times) cfg = None try: cfg = config.read_config() except config.ConfigError as ce: ce.log_and_exit() try: process_opts(cfg, opts, times) except LVEVersionError as lve_error: config.log.error(str(lve_error)) sys.exit(1)
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