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certbot
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log.py
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"""Logging utilities for Certbot. The best way to use this module is through `pre_arg_parse_setup` and `post_arg_parse_setup`. `pre_arg_parse_setup` configures a minimal terminal logger and ensures a detailed log is written to a secure temporary file if Certbot exits before `post_arg_parse_setup` is called. `post_arg_parse_setup` relies on the parsed command line arguments and does the full logging setup with terminal and rotating file handling as configured by the user. Any logged messages before `post_arg_parse_setup` is called are sent to the rotating file handler. Special care is taken by both methods to ensure all errors are logged and properly flushed before program exit. The `logging` module is useful for recording messages about about what Certbot is doing under the hood, but do not necessarily need to be shown to the user on the terminal. The default verbosity is WARNING. The preferred method to display important information to the user is to use `certbot.display.util` and `certbot.display.ops`. """ import functools import logging import logging.handlers import shutil import sys import tempfile import traceback from types import TracebackType from typing import Any from typing import cast from typing import IO from typing import Optional from typing import Tuple from typing import Type from acme import messages from certbot import configuration from certbot import errors from certbot import util from certbot._internal import constants from certbot._internal.display import util as display_util from certbot.compat import os # Logging format CLI_FMT = "%(message)s" FILE_FMT = "%(asctime)s:%(levelname)s:%(name)s:%(message)s" logger = logging.getLogger(__name__) def pre_arg_parse_setup() -> None: """Setup logging before command line arguments are parsed. Terminal logging is setup using `certbot._internal.constants.QUIET_LOGGING_LEVEL` so Certbot is as quiet as possible. File logging is setup so that logging messages are buffered in memory. If Certbot exits before `post_arg_parse_setup` is called, these buffered messages are written to a temporary file. If Certbot doesn't exit, `post_arg_parse_setup` writes the messages to the normal log files. This function also sets `logging.shutdown` to be called on program exit which automatically flushes logging handlers and `sys.excepthook` to properly log/display fatal exceptions. """ temp_handler = TempHandler() temp_handler.setFormatter(logging.Formatter(FILE_FMT)) temp_handler.setLevel(logging.DEBUG) memory_handler = MemoryHandler(temp_handler) stream_handler = ColoredStreamHandler() stream_handler.setFormatter(logging.Formatter(CLI_FMT)) # The pre-argparse logging level is set to WARNING here. This is to ensure that # deprecated flags (see DeprecatedArgumentAction) print something to the terminal. # See https://github.com/certbot/certbot/issues/9618. stream_handler.setLevel(logging.WARNING) root_logger = logging.getLogger() root_logger.setLevel(logging.DEBUG) # send all records to handlers root_logger.addHandler(memory_handler) root_logger.addHandler(stream_handler) # logging.shutdown will flush the memory handler because flush() and # close() are explicitly called util.atexit_register(logging.shutdown) sys.excepthook = functools.partial( pre_arg_parse_except_hook, memory_handler, debug='--debug' in sys.argv, quiet='--quiet' in sys.argv or '-q' in sys.argv, log_path=temp_handler.path) def post_arg_parse_setup(config: configuration.NamespaceConfig) -> None: """Setup logging after command line arguments are parsed. This function assumes `pre_arg_parse_setup` was called earlier and the root logging configuration has not been modified. A rotating file logging handler is created and the buffered log messages are sent to that handler. Terminal logging output is set to the level requested by the user. :param certbot.configuration.NamespaceConfig config: Configuration object """ file_handler, file_path = setup_log_file_handler( config, 'letsencrypt.log', FILE_FMT) root_logger = logging.getLogger() memory_handler = stderr_handler = None for handler in root_logger.handlers: if isinstance(handler, ColoredStreamHandler): stderr_handler = handler elif isinstance(handler, MemoryHandler): memory_handler = handler msg = 'Previously configured logging handlers have been removed!' assert memory_handler is not None and stderr_handler is not None, msg root_logger.addHandler(file_handler) root_logger.removeHandler(memory_handler) temp_handler = getattr(memory_handler, 'target', None) memory_handler.setTarget(file_handler) # pylint: disable=no-member memory_handler.flush(force=True) # pylint: disable=unexpected-keyword-arg memory_handler.close() if temp_handler: temp_handler.close() if config.quiet: level = constants.QUIET_LOGGING_LEVEL elif config.verbose_level is not None: level = constants.DEFAULT_LOGGING_LEVEL - int(config.verbose_level) * 10 else: level = constants.DEFAULT_LOGGING_LEVEL - config.verbose_count * 10 stderr_handler.setLevel(level) logger.debug('Root logging level set at %d', level) if not config.quiet: print(f'Saving debug log to {file_path}', file=sys.stderr) sys.excepthook = functools.partial( post_arg_parse_except_hook, debug=config.debug, quiet=config.quiet, log_path=file_path) def setup_log_file_handler(config: configuration.NamespaceConfig, logfile: str, fmt: str) -> Tuple[logging.Handler, str]: """Setup file debug logging. :param certbot.configuration.NamespaceConfig config: Configuration object :param str logfile: basename for the log file :param str fmt: logging format string :returns: file handler and absolute path to the log file :rtype: tuple """ # TODO: logs might contain sensitive data such as contents of the # private key! #525 util.set_up_core_dir(config.logs_dir, 0o700, config.strict_permissions) log_file_path = os.path.join(config.logs_dir, logfile) try: handler = logging.handlers.RotatingFileHandler( log_file_path, maxBytes=2 ** 20, backupCount=config.max_log_backups) except IOError as error: raise errors.Error(util.PERM_ERR_FMT.format(error)) # rotate on each invocation, rollover only possible when maxBytes # is nonzero and backupCount is nonzero, so we set maxBytes as big # as possible not to overrun in single CLI invocation (1MB). handler.doRollover() # TODO: creates empty letsencrypt.log.1 file handler.setLevel(logging.DEBUG) handler_formatter = logging.Formatter(fmt=fmt) handler.setFormatter(handler_formatter) return handler, log_file_path class ColoredStreamHandler(logging.StreamHandler): """Sends colored logging output to a stream. If the specified stream is not a tty, the class works like the standard `logging.StreamHandler`. Default red_level is `logging.WARNING`. :ivar bool colored: True if output should be colored :ivar bool red_level: The level at which to output """ def __init__(self, stream: Optional[IO] = None) -> None: super().__init__(stream) self.colored = (sys.stderr.isatty() if stream is None else stream.isatty()) self.red_level = logging.WARNING def format(self, record: logging.LogRecord) -> str: """Formats the string representation of record. :param logging.LogRecord record: Record to be formatted :returns: Formatted, string representation of record :rtype: str """ out = super().format(record) if self.colored and record.levelno >= self.red_level: return ''.join((util.ANSI_SGR_RED, out, util.ANSI_SGR_RESET)) return out class MemoryHandler(logging.handlers.MemoryHandler): """Buffers logging messages in memory until the buffer is flushed. This differs from `logging.handlers.MemoryHandler` in that flushing only happens when flush(force=True) is called. """ def __init__(self, target: Optional[logging.Handler] = None, capacity: int = 10000) -> None: # capacity doesn't matter because should_flush() is overridden super().__init__(capacity, target=target) def close(self) -> None: """Close the memory handler, but don't set the target to None.""" # This allows the logging module which may only have a weak # reference to the target handler to properly flush and close it. target = getattr(self, 'target') super().close() self.target = target def flush(self, force: bool = False) -> None: # pylint: disable=arguments-differ """Flush the buffer if force=True. If force=False, this call is a noop. :param bool force: True if the buffer should be flushed. """ # This method allows flush() calls in logging.shutdown to be a # noop so we can control when this handler is flushed. if force: super().flush() def shouldFlush(self, record: logging.LogRecord) -> bool: """Should the buffer be automatically flushed? :param logging.LogRecord record: log record to be considered :returns: False because the buffer should never be auto-flushed :rtype: bool """ return False class TempHandler(logging.StreamHandler): """Safely logs messages to a temporary file. The file is created with permissions 600. If no log records are sent to this handler, the temporary file is deleted when the handler is closed. :ivar str path: file system path to the temporary log file """ def __init__(self) -> None: self._workdir = tempfile.mkdtemp(prefix="certbot-log-") self.path = os.path.join(self._workdir, 'log') stream = util.safe_open(self.path, mode='w', chmod=0o600) super().__init__(stream) # Super constructor assigns the provided stream object to self.stream. # Let's help mypy be aware of this by giving a type hint. self.stream: IO[str] self._delete = True def emit(self, record: logging.LogRecord) -> None: """Log the specified logging record. :param logging.LogRecord record: Record to be formatted """ self._delete = False super().emit(record) def close(self) -> None: """Close the handler and the temporary log file. The temporary log file is deleted if it wasn't used. """ self.acquire() try: # StreamHandler.close() doesn't close the stream to allow a # stream like stderr to be used self.stream.close() if self._delete: shutil.rmtree(self._workdir) self._delete = False super().close() finally: self.release() def pre_arg_parse_except_hook(memory_handler: MemoryHandler, *args: Any, **kwargs: Any) -> None: """A simple wrapper around post_arg_parse_except_hook. The additional functionality provided by this wrapper is the memory handler will be flushed before Certbot exits. This allows us to write logging messages to a temporary file if we crashed before logging was fully configured. Since sys.excepthook isn't called on SystemExit exceptions, the memory handler will not be flushed in this case which prevents us from creating temporary log files when argparse exits because a command line argument was invalid or -h, --help, or --version was provided on the command line. :param MemoryHandler memory_handler: memory handler to flush :param tuple args: args for post_arg_parse_except_hook :param dict kwargs: kwargs for post_arg_parse_except_hook """ try: post_arg_parse_except_hook(*args, **kwargs) finally: # flush() is called here so messages logged during # post_arg_parse_except_hook are also flushed. memory_handler.flush(force=True) def post_arg_parse_except_hook(exc_type: Type[BaseException], exc_value: BaseException, trace: TracebackType, debug: bool, quiet: bool, log_path: str) -> None: """Logs fatal exceptions and reports them to the user. If debug is True, the full exception and traceback is shown to the user, otherwise, it is suppressed. sys.exit is always called with a nonzero status. :param type exc_type: type of the raised exception :param BaseException exc_value: raised exception :param traceback trace: traceback of where the exception was raised :param bool debug: True if the traceback should be shown to the user :param bool quiet: True if Certbot is running in quiet mode :param str log_path: path to file or directory containing the log """ exc_info = (exc_type, exc_value, trace) # Only print human advice if not running under --quiet def exit_func() -> None: if quiet: sys.exit(1) else: exit_with_advice(log_path) # constants.QUIET_LOGGING_LEVEL or higher should be used to # display message the user, otherwise, a lower level like # logger.DEBUG should be used if debug or not issubclass(exc_type, Exception): assert constants.QUIET_LOGGING_LEVEL <= logging.ERROR if exc_type is KeyboardInterrupt: logger.error('Exiting due to user request.') sys.exit(1) logger.error('Exiting abnormally:', exc_info=exc_info) else: logger.debug('Exiting abnormally:', exc_info=exc_info) # Use logger to print the error message to take advantage of # our logger printing warnings and errors in red text. if issubclass(exc_type, errors.Error): logger.error(str(exc_value)) exit_func() logger.error('An unexpected error occurred:') if messages.is_acme_error(exc_value): logger.error(display_util.describe_acme_error(cast(messages.Error, exc_value))) else: output = traceback.format_exception_only(exc_type, exc_value) # format_exception_only returns a list of strings each # terminated by a newline. We combine them into one string # and remove the final newline before passing it to # logger.error. logger.error(''.join(output).rstrip()) exit_func() def exit_with_advice(log_path: str) -> None: """Print a link to the community forums, the debug log path, and exit The message is printed to stderr and the program will exit with a nonzero status. :param str log_path: path to file or directory containing the log """ msg = ("Ask for help or search for solutions at https://community.letsencrypt.org. " "See the ") if os.path.isdir(log_path): msg += f'logfiles in {log_path} ' else: msg += f"logfile {log_path} " msg += 'or re-run Certbot with -v for more details.' sys.exit(msg)