baseimage-tutorial-framework/lib/tfw/config/log.py

# pylint: disable=bad-whitespace
from sys import stderr
from collections import deque
from datetime import datetime
from traceback import format_exception, walk_tb
from logging import DEBUG, getLogger, Handler, Formatter, Filter

TFW_LOG_PATH = '/var/log/tfw.log'


class COLOR:
    BLACK       = '\033[30m'
    GREY        = '\033[30;1m'
    RED         = '\033[31m'
    BOLDRED     = '\033[31;1m'
    GREEN       = '\033[32m'
    BOLDGREEN   = '\033[32;1m'
    ORANGE      = '\033[33m'
    YELLOW      = '\033[33;1m'
    BLUE        = '\033[34m'
    BOLDBLUE    = '\033[34;1m'
    MAGENTA     = '\033[35m'
    BOLDMAGENTA = '\033[35;1m'
    CYAN        = '\033[36m'
    BOLDCYAN    = '\033[36;1m'
    WHITE       = '\033[37m'
    BOLDWHITE   = '\033[37;1m'
    RESET       = '\033[0m'


class TFWLog:
    def __init__(self, path=TFW_LOG_PATH, level=DEBUG):
        self.log = getLogger()
        self.old_level = self.log.level
        self.new_level = level
        self.handler = TFWLogHandler(path)
        self.handler.setFormatter(TFWLogFormatter())

    def start(self):
        self.log.setLevel(self.new_level)
        self.log.addHandler(self.handler)
        self.log.info('Logging started.')

    def stop(self):
        self.log.info('Stop logging.')
        self.log.setLevel(self.old_level)
        self.handler.close()
        self.log.removeHandler(self.handler)


class TFWLogHandler(Handler):
    def __init__(self, path):
        self.logfile = open(path, 'a+')
        super().__init__()

    def emit(self, record):
        short_entry, long_entry = self.format(record)
        stderr.write(short_entry+'\n')
        self.logfile.write(long_entry+'\n')
        stderr.flush()
        self.logfile.flush()

    def close(self):
        self.logfile.close()

class TFWLogFormatter(Formatter):
    severity = {
        'CRITICAL' : COLOR.BOLDRED,
        'ERROR'    : COLOR.RED,
        'WARNING'  : COLOR.YELLOW,
        'INFO'     : COLOR.BOLDGREEN,
        'DEBUG'    : COLOR.BOLDWHITE,
        'NOTSET'   : COLOR.CYAN
    }

    def __init__(self):
        self.last_trace = None
        super().__init__()

    def format(self, record):
        date = datetime.utcfromtimestamp(record.created).strftime('%H:%M:%S')
        if record.args:
            tuple_args = (record.args,) if isinstance(record.args, dict) else record.args
            clean_args = tuple((self.trim(arg) for arg in tuple_args))
            short_message = record.msg % clean_args
            long_message = record.msg % record.args
        else:
            short_message = record.msg
            long_message = record.msg

        if record.exc_info:
            current_trace = self.fetch_exception_origin(record.exc_info[2])
            if current_trace != self.last_trace:
                self.last_trace = current_trace
                trace = '\n'+''.join(format_exception(*record.exc_info))
            else:
                trace = (f'\nSee previous traceback...\n'
                         f'{record.exc_info[0].__name__}: {record.exc_info[1]}')
        else:
            trace = ''

        short_entry = (f'[{COLOR.GREY}{date}{COLOR.RESET}|>'
                       f'{self.severity[record.levelname]}{record.module}:'
                       f'{record.levelname.lower()}{COLOR.RESET}] {short_message}'
                       f'{trace}')
        long_entry = (f'[{date}|>{record.module}:{record.levelname.lower()}] '
                      f'{long_message}{trace}')
        return short_entry, long_entry

    def trim(self, value, in_dict=False):
        if isinstance(value, dict):
            trimmed = {k: self.trim(v, True) for k, v in value.items()}
            return trimmed if in_dict else str(trimmed)
        if isinstance(value, (int, float)):
            return value
        value_str = str(value)
        return value_str if len(value_str) <= 20 else f'{value_str[:20]}...'

    @staticmethod
    def fetch_exception_origin(trace):
        return deque(walk_tb(trace), maxlen=1).pop()


class TFWLogWhitelistFilter(Filter):
    def __init__(self, names):
        self.names = names
        super().__init__()

    def filter(self, record):
        return record.module in self.names


class TFWLogBlacklistFilter(Filter):
    def __init__(self, names):
        self.names = names
        super().__init__()

    def filter(self, record):
        return record.module not in self.names