Source code for habitat.utils.startup

# Copyright 2011 (C) Daniel Richman
# This file is part of habitat.
# habitat 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 3 of the License, or
# (at your option) any later version.
# habitat 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 habitat.  If not, see <>.

"""Useful functions for daemon startup"""

import sys
import logging
import logging.handlers
import yaml

logger = logging.getLogger("habitat.utils.startup")

[docs]def load_config(): """ Loads the habitat config. The path to the configuration YAML file can be specified as the single command line argument (read from ``sys.argv[1]``) or will default to ``./habitat.yml``. """ if len(sys.argv) == 2: filename = sys.argv[1] elif len(sys.argv) <= 1: filename = "./habitat.yml" else: raise ValueError("Expected one command line argument only.") with open(filename) as f: config = yaml.safe_load(f) return config
def _get_logging_level(value): value = value.upper() if value == "NONE": return None else: return getattr(logging, value)
[docs]class null_logger(logging.Handler): """A python logging handler that discards log messages silently.""" def emit(self, record): pass
_format_email = \ """%(levelname)s from logger %(name)s (thread %(threadName)s) Time: %(asctime)s Location: %(pathname)s:%(lineno)d Module: %(module)s Function: %(funcName)s %(message)s""" _format_string = \ "[%(asctime)s] %(levelname)s %(name)s %(threadName)s: %(message)s"
[docs]def setup_logging(config, daemon_name): """ **setup_logging** initalises the :py:mod:`Python logging module <logging>`. It will initalise the 'habitat' logger and creates one, two, or no Handlers, depending on the values provided for ``log_file_level`` and ``log_stderr_level`` in *config*. """ root_logger = logging.getLogger() # Enable all messages at the logger level, then filter them in each # handler. root_logger.setLevel(logging.DEBUG) # Bug pivotal:11844615, set restkit's level to WARNING to lower spam logging.getLogger("restkit").setLevel(logging.WARNING) have_handlers = False levels = config["log_levels"] stderr_level = _get_logging_level(levels.get("stderr", "NONE")) file_level = _get_logging_level(levels.get("file", "NONE")) email_level = _get_logging_level(levels.get("email", "NONE")) if stderr_level != None: stderr_handler = logging.StreamHandler() stderr_handler.setFormatter(logging.Formatter(_format_string)) stderr_handler.setLevel(stderr_level) root_logger.addHandler(stderr_handler) have_handlers = True if file_level != None: file_name = config[daemon_name]["log_file"] file_handler = logging.handlers.WatchedFileHandler(file_name) file_handler.setFormatter(logging.Formatter(_format_string)) file_handler.setLevel(file_level) root_logger.addHandler(file_handler) have_handlers = True if email_level != None: emails_to = config["log_emails"]["to"] emails_from = config["log_emails"]["from"] email_server = config["log_emails"]["server"] if not isinstance(emails_to, list): emails_to = [emails_to] mail_handler = logging.handlers.SMTPHandler( email_server, emails_from, emails_to, daemon_name) mail_handler.setLevel(email_level) mail_handler.setFormatter(logging.Formatter(_format_email)) root_logger.addHandler(mail_handler) have_handlers = True if not have_handlers: # logging gets annoyed if there isn't atleast one handler. # If we're meant to be totally silent... root_logger.addHandler(null_logger())"Log initialised")
[docs]def main(main_class): """ Main function for habitat daemons. Loads config, sets up logging, and runs. ``main_class.__name__.lower()`` will be used as the config sub section and passed as *daemon_name*. *main_class* specifies a class from which an object will be created. It will be initialised with arguments (config, daemon_name) and then the method run() of the object will be invoked. """ config = load_config() daemon_name = main_class.__name__.lower() setup_logging(config, daemon_name) main_class(config, daemon_name).run()