fm-orchestrator/module_build_service/logger.py

# -*- coding: utf-8 -*-


# Copyright (c) 2016  Red Hat, Inc.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
# Written by Jan Kaluza <jkaluza@redhat.com>

"""
Logging functions.

At the beginning of the MBS flow, init_logging(conf) must be called.

After that, logging from any module is possible using Python's "logging"
module as showed at
<https://docs.python.org/3/howto/logging.html#logging-basic-tutorial>.

Examples:

import logging

logging.debug("Phasers are set to stun.")
logging.info("%s tried to build something", username)
logging.warn("%s failed to build", task_id)

"""

import os
import logging

levels = {}
levels["debug"] = logging.DEBUG
levels["error"] = logging.ERROR
levels["warning"] = logging.WARNING
levels["info"] = logging.INFO

level_flags = {}
level_flags["debug"] = levels["debug"]
level_flags["verbose"] = levels["info"]
level_flags["quiet"] = levels["error"]


log_format = '%(asctime)s - %(threadName)s - %(name)s - %(levelname)s - %(message)s'


class ModuleBuildFileHandler(logging.FileHandler):
    """
    FileHandler subclass which handles only messages generated during
    particular module build with `build_id` set in its constructor.
    """
    def __init__(self, build_id, filename, mode='a', encoding=None, delay=0):
        logging.FileHandler.__init__(self, filename, mode, encoding, delay)
        self.build_id = build_id

    def emit(self, record):
        # Imported here because of importing cycle between __init__.py,
        # scheduler and models.
        from module_build_service.scheduler.consumer import MBSConsumer

        # Check the currently handled module build and emit the message only
        # if it's associated with current module.
        build_id = MBSConsumer.current_module_build_id
        if not build_id or build_id != self.build_id:
            return

        logging.FileHandler.emit(self, record)


class ModuleBuildLogs(object):
    """
    Manages ModuleBuildFileHandler logging handlers.
    """
    def __init__(self, build_logs_dir, build_logs_name_format):
        """
        Creates new ModuleBuildLogs instance. Module build logs are stored
        to `build_logs_dir` directory.
        """
        self.handlers = {}
        self.build_logs_dir = build_logs_dir
        self.build_logs_name_format = build_logs_name_format

    def path(self, build):
        """
        Returns the full path to build log of module with id `build_id`.
        """
        path = os.path.join(self.build_logs_dir, self.name(build))
        return path

    def name(self, build):
        """
        Returns the filename for a module build
        """
        name = self.build_logs_name_format.format(**build.json())
        return name

    def start(self, build):
        """
        Starts logging build log for module with `build_id` id.
        """
        if not self.build_logs_dir:
            return

        if build.id in self.handlers:
            return

        # Create and add ModuleBuildFileHandler.
        handler = ModuleBuildFileHandler(build.id, self.path(build))
        handler.setFormatter(logging.Formatter(log_format, None))
        log = logging.getLogger()
        log.addHandler(handler)

        self.handlers[build.id] = handler

    def stop(self, build):
        """
        Stops logging build log for module with `build_id` id. It does *not*
        remove the build log from fs.
        """
        if build.id not in self.handlers:
            return

        handler = self.handlers[build.id]
        handler.flush()
        handler.close()

        # Remove the log handler.
        log = logging.getLogger()
        log.removeHandler(handler)
        del self.handlers[build.id]


def str_to_log_level(level):
    """
    Returns internal representation of logging level defined
    by the string `level`.

    Available levels are: debug, info, warning, error
    """
    if level not in levels:
        return logging.NOTSET

    return levels[level]


def supported_log_backends():
    return ("console", "journal", "file")


def init_logging(conf):
    """
    Initializes logging according to configuration file.
    """
    log_backend = conf.log_backend

    if not log_backend or len(log_backend) == 0 or log_backend == "console":
        logging.basicConfig(level=conf.log_level, format=log_format)
        log = logging.getLogger()
        log.setLevel(conf.log_level)
    elif log_backend == "journal":
        logging.basicConfig(level=conf.log_level, format=log_format)
        try:
            from systemd import journal
        except Exception:
            raise ValueError("systemd.journal module is not installed")

        log = logging.getLogger()
        log.propagate = False
        log.addHandler(journal.JournalHandler())
    else:
        logging.basicConfig(filename=conf.log_file, level=conf.log_level,
                            format=log_format)
        log = logging.getLogger()