systemd.journal — python-systemd 236 documentation

python-systemd · man pages · directives python-systemd 236

# Source code for systemd.journal

    # SPDX-License-Identifier: LGPL-2.1-or-later

    import sys as _sys
    import datetime as _datetime
    import uuid as _uuid
    import traceback as _traceback
    import os as _os
    import logging as _logging
    from syslog import (LOG_EMERG, LOG_ALERT, LOG_CRIT, LOG_ERR,
                        LOG_WARNING, LOG_NOTICE, LOG_INFO, LOG_DEBUG)

    from ._journal import __version__, sendv, stream_fd
    from ._reader import (_Reader, NOP, APPEND, INVALIDATE,
                          LOCAL_ONLY, RUNTIME_ONLY,
                          SYSTEM, SYSTEM_ONLY, CURRENT_USER,
                          OS_ROOT,
                          _get_catalog, Monotonic)
    from . import id128 as _id128

    def _convert_monotonic(m):
        return Monotonic((_datetime.timedelta(microseconds=m[0]),
                          _uuid.UUID(bytes=m[1])))

    def _convert_source_monotonic(s):
        return _datetime.timedelta(microseconds=int(s))

    try:
        _LOCAL_TIMEZONE = _datetime.datetime.now().astimezone().tzinfo
    except TypeError:
        _LOCAL_TIMEZONE = None

    def _convert_realtime(t):
        return _datetime.datetime.fromtimestamp(t / 1000000, _LOCAL_TIMEZONE)

    def _convert_timestamp(s):
        return _datetime.datetime.fromtimestamp(int(s) / 1000000, _LOCAL_TIMEZONE)

    def _convert_trivial(x):
        return x

    def _convert_uuid(s):
        return _uuid.UUID(s.decode())

    DEFAULT_CONVERTERS = {
        'MESSAGE_ID': _convert_uuid,
        '_MACHINE_ID': _convert_uuid,
        '_BOOT_ID': _convert_uuid,
        'PRIORITY': int,
        'LEADER': int,
        'SESSION_ID': int,
        'USERSPACE_USEC': int,
        'INITRD_USEC': int,
        'KERNEL_USEC': int,
        '_UID': int,
        '_GID': int,
        '_PID': int,
        'SYSLOG_FACILITY': int,
        'SYSLOG_PID': int,
        '_AUDIT_SESSION': int,
        '_AUDIT_LOGINUID': int,
        '_SYSTEMD_SESSION': int,
        '_SYSTEMD_OWNER_UID': int,
        'CODE_LINE': int,
        'ERRNO': int,
        'EXIT_STATUS': int,
        '_SOURCE_REALTIME_TIMESTAMP': _convert_timestamp,
        '__REALTIME_TIMESTAMP': _convert_realtime,
        '_SOURCE_MONOTONIC_TIMESTAMP': _convert_source_monotonic,
        '__MONOTONIC_TIMESTAMP': _convert_monotonic,
        '__CURSOR': _convert_trivial,
        'COREDUMP': bytes,
        'COREDUMP_PID': int,
        'COREDUMP_UID': int,
        'COREDUMP_GID': int,
        'COREDUMP_SESSION': int,
        'COREDUMP_SIGNAL': int,
        'COREDUMP_TIMESTAMP': _convert_timestamp,
    }

    _IDENT_CHARACTER = set('ABCDEFGHIJKLMNOPQRTSUVWXYZ_0123456789')

    def _valid_field_name(s):
        return not (set(s) - _IDENT_CHARACTER)

    class Reader(_Reader):
        """Access systemd journal entries.

        Entries are subject to filtering and limits, see `add_match`, `this_boot`,
        `this_machine` functions and the `data_treshold` attribute.

        Note that in order to access the system journal, a non-root user must have
        the necessary privileges, see journalctl(1) for details.  Unprivileged users
        can access only their own journal.

        Example usage to print out all informational or higher level messages for
        systemd-udevd for this boot:

        >>> from systemd import journal
        >>> j = journal.Reader()
        >>> j.this_boot()
        >>> j.log_level(journal.LOG_INFO)
        >>> j.add_match(_SYSTEMD_UNIT="systemd-udevd.service")
        >>> for entry in j:                                 # doctest: +SKIP
        ...    print(entry['MESSAGE'])
        starting version ...

        See systemd.journal-fields(7) for more info on typical fields found in the
        journal.

        """

        def __init__(self, flags=None, path=None, files=None, converters=None, namespace=None):
            """Create a new Reader.

            Argument `flags` defines the open flags of the journal, which can be one
            of, or ORed combination of constants: LOCAL_ONLY (default) opens journal
            on local machine only; RUNTIME_ONLY opens only volatile journal files;
            and SYSTEM_ONLY opens only journal files of system services and the kernel.

            Argument `path` is the directory of journal files, either a file system
            path or a file descriptor. Specify `namespace` to read from specific journal
            namespace. Note that `flags`, `path`, `files` and `namespace` are exclusive.

            Argument `converters` is a dictionary which updates the
            DEFAULT_CONVERTERS to convert journal field values. Field names are used
            as keys into this dictionary. The values must be single argument
            functions, which take a `bytes` object and return a converted
            value. When there's no entry for a field name, then the default UTF-8
            decoding will be attempted. If the conversion fails with a ValueError,
            unconverted bytes object will be returned. (Note that ValueEror is a
            superclass of UnicodeDecodeError).

            Reader implements the context manager protocol: the journal will be
            closed when exiting the block.
            """
            if flags is None:
                if path is None and files is None:
                    # This mimics journalctl behaviour of default to local journal only
                    flags = LOCAL_ONLY
                else:
                    flags = 0

            super(Reader, self).__init__(flags, path, files, namespace)
            self.converters = DEFAULT_CONVERTERS.copy()
            if converters is not None:
                self.converters.update(converters)

        def _convert_field(self, key, value):
            """Convert value using self.converters[key].

            If `key` is not present in self.converters, a standard unicode decoding
            will be attempted.  If the conversion (either key-specific or the
            default one) fails with a ValueError, the original bytes object will be
            returned.
            """
            convert = self.converters.get(key, bytes.decode)
            try:
                return convert(value)
            except ValueError:
                # Leave in default bytes
                return value

        def _convert_entry(self, entry):
            """Convert entire journal entry utilising _convert_field."""
            result = {}
            for key, value in entry.items():
                if isinstance(value, list):
                    result[key] = [self._convert_field(key, val) for val in value]
                else:
                    result[key] = self._convert_field(key, value)
            return result

        def __iter__(self):
            """Return self.

            Part of the iterator protocol.
            """
            return self

        def __next__(self):
            """Return the next entry in the journal.

            Returns self.get_next() or raises StopIteration.

            Part of the iterator protocol.
            """
            ans = self.get_next()
            if ans:
                return ans
            else:
                raise StopIteration()

        def add_match(self, *args, **kwargs):
            """Add one or more matches to the filter journal log entries.

            All matches of different field are combined with logical AND, and
            matches of the same field are automatically combined with logical OR.
            Matches can be passed as strings of form "FIELD=value", or keyword
            arguments FIELD="value".
            """
            args = list(args)
            args.extend(_make_line(key, val) for key, val in kwargs.items())
            for arg in args:
                super(Reader, self).add_match(arg)

        def get_next(self, skip=1):
            r"""Return the next log entry as a dictionary.

            Entries will be processed with converters specified during Reader
            creation.

            Optional `skip` value will return the `skip`-th log entry.

            Currently a standard dictionary of fields is returned, but in the
            future this might be changed to a different mapping type, so the
            calling code should not make assumptions about a specific type.
            """
            if super(Reader, self)._next(skip):
                entry = super(Reader, self)._get_all()
                if entry:
                    entry['__REALTIME_TIMESTAMP'] = self._get_realtime()
                    entry['__MONOTONIC_TIMESTAMP'] = self._get_monotonic()
                    entry['__CURSOR'] = self._get_cursor()
                    return self._convert_entry(entry)
            return dict()

        def get_previous(self, skip=1):
            r"""Return the previous log entry.

            Equivalent to get_next(-skip).

            Optional `skip` value will return the -`skip`-th log entry.

            Entries will be processed with converters specified during Reader
            creation.

            Currently a standard dictionary of fields is returned, but in the
            future this might be changed to a different mapping type, so the
            calling code should not make assumptions about a specific type.
            """
            return self.get_next(-skip)

        def query_unique(self, field):
            """Return a list of unique values appearing in the journal for the given
            `field`.

            Note this does not respect any journal matches.

            Entries will be processed with converters specified during
            Reader creation.
            """
            return set(self._convert_field(field, value)
                       for value in super(Reader, self).query_unique(field))

        def wait(self, timeout=None):
            """Wait for a change in the journal.

            `timeout` is the maximum time in seconds to wait, or None which
            means to wait forever.

            Returns one of NOP (no change), APPEND (new entries have been added to
            the end of the journal), or INVALIDATE (journal files have been added or
            removed).
            """
            us = -1 if timeout is None else int(timeout * 1000000)
            return super(Reader, self).wait(us)

        def seek_realtime(self, realtime):
            """Seek to a matching journal entry nearest to `timestamp` time.

            Argument `realtime` must be either an integer UNIX timestamp (in
            microseconds since the beginning of the UNIX epoch), or an float UNIX
            timestamp (in seconds since the beginning of the UNIX epoch), or a
            datetime.datetime instance. The integer form is deprecated.

            >>> import time
            >>> from systemd import journal

            >>> yesterday = time.time() - 24 * 60**2
            >>> j = journal.Reader()
            >>> j.seek_realtime(yesterday)
            """
            if isinstance(realtime, _datetime.datetime):
                realtime = int(realtime.astimezone().timestamp() * 1000000)
            elif not isinstance(realtime, int):
                realtime = int(realtime * 1000000)
            return super(Reader, self).seek_realtime(realtime)

        def get_start(self):
            start = super(Reader, self)._get_start()
            return _convert_realtime(start)

        def get_end(self):
            end = super(Reader, self)._get_end()
            return _convert_realtime(end)

        def seek_monotonic(self, monotonic, bootid=None):
            """Seek to a matching journal entry nearest to `monotonic` time.

            Argument `monotonic` is a timestamp from boot in either seconds or a
            datetime.timedelta instance. Argument `bootid` is a string or UUID
            representing which boot the monotonic time is reference to. Defaults to
            current bootid.
            """
            if isinstance(monotonic, _datetime.timedelta):
                monotonic = monotonic.total_seconds()
            monotonic = int(monotonic * 1000000)
            if isinstance(bootid, _uuid.UUID):
                bootid = bootid.hex
            return super(Reader, self).seek_monotonic(monotonic, bootid)

        def log_level(self, level):
            """Set maximum log `level` by setting matches for PRIORITY.
            """
            if 0 <= level <= 7:
                for i in range(level+1):
                    self.add_match(PRIORITY="%d" % i)
            else:
                raise ValueError("Log level must be 0 <= level <= 7")

        def messageid_match(self, messageid):
            """Add match for log entries with specified `messageid`.

            `messageid` can be string of hexadicimal digits or a UUID
            instance. Standard message IDs can be found in systemd.id128.

            Equivalent to add_match(MESSAGE_ID=`messageid`).
            """
            if isinstance(messageid, _uuid.UUID):
                messageid = messageid.hex
            self.add_match(MESSAGE_ID=messageid)

        def this_boot(self, bootid=None):
            """Add match for _BOOT_ID for current boot or the specified boot ID.

            If specified, bootid should be either a UUID or a 32 digit hex number.

            Equivalent to add_match(_BOOT_ID='bootid').
            """
            if bootid is None:
                bootid = _id128.get_boot().hex
            else:
                bootid = getattr(bootid, 'hex', bootid)
            self.add_match(_BOOT_ID=bootid)

        def this_machine(self, machineid=None):
            """Add match for _MACHINE_ID equal to the ID of this machine.

            If specified, machineid should be either a UUID or a 32 digit hex
            number.

            Equivalent to add_match(_MACHINE_ID='machineid').
            """
            if machineid is None:
                machineid = _id128.get_machine().hex
            else:
                machineid = getattr(machineid, 'hex', machineid)
            self.add_match(_MACHINE_ID=machineid)

    def get_catalog(mid):
        """Return catalog entry for the specified ID.

        `mid` should be either a UUID or a 32 digit hex number.
        """
        if isinstance(mid, _uuid.UUID):
            mid = mid.hex
        return _get_catalog(mid)

    def _make_line(field, value):
        if isinstance(value, bytes):
            return field.encode('utf-8') + b'=' + value
        elif isinstance(value, str):
            return field + '=' + value
        else:
            return field + '=' + str(value)

    def send(MESSAGE, MESSAGE_ID=None,
             CODE_FILE=None, CODE_LINE=None, CODE_FUNC=None,
             **kwargs):
        r"""Send a message to the journal.

        >>> from systemd import journal
        >>> journal.send('Hello world')
        >>> journal.send('Hello, again, world', FIELD2='Greetings!')
        >>> journal.send('Binary message', BINARY=b'\xde\xad\xbe\xef')

        Value of the MESSAGE argument will be used for the MESSAGE= field. MESSAGE
        must be a string and will be sent as UTF-8 to the journal.

        MESSAGE_ID can be given to uniquely identify the type of message. It must be
        a string or a uuid.UUID object.

        CODE_LINE, CODE_FILE, and CODE_FUNC can be specified to identify the caller.
        Unless at least on of the three is given, values are extracted from the
        stack frame of the caller of send(). CODE_FILE and CODE_FUNC must be
        strings, CODE_LINE must be an integer.

        Additional fields for the journal entry can only be specified as keyword
        arguments. The payload can be either a string or bytes. A string will be
        sent as UTF-8, and bytes will be sent as-is to the journal.

        Other useful fields include PRIORITY, SYSLOG_FACILITY, SYSLOG_IDENTIFIER,
        SYSLOG_PID.
        """

        args = ['MESSAGE=' + MESSAGE]

        if MESSAGE_ID is not None:
            id = getattr(MESSAGE_ID, 'hex', MESSAGE_ID)
            args.append('MESSAGE_ID=' + id)

        if CODE_LINE is CODE_FILE is CODE_FUNC is None:
            CODE_FILE, CODE_LINE, CODE_FUNC = _traceback.extract_stack(limit=2)[0][:3]
        if CODE_FILE is not None:
            args.append('CODE_FILE=' + CODE_FILE)
        if CODE_LINE is not None:
            args.append('CODE_LINE={:d}'.format(CODE_LINE))
        if CODE_FUNC is not None:
            args.append('CODE_FUNC=' + CODE_FUNC)

        args.extend(_make_line(key, val) for key, val in kwargs.items())
        return sendv(*args)

    def stream(identifier=None, priority=LOG_INFO, level_prefix=False):
        r"""Return a file object wrapping a stream to journal.

        Log messages written to this file as simple newline sepearted text strings
        are written to the journal.

        The file will be line buffered, so messages are actually sent after a
        newline character is written.

        >>> from systemd import journal
        >>> stream = journal.stream('myapp')                       # doctest: +SKIP
        >>> res = stream.write('message...\n')                     # doctest: +SKIP

        will produce the following message in the journal::

          PRIORITY=7
          SYSLOG_IDENTIFIER=myapp
          MESSAGE=message...

        If identifier is None, a suitable default based on sys.argv[0] will be used.

        This interface can be used conveniently with the print function:

        >>> stream = journal.stream()                              # doctest: +SKIP
        >>> print('message...', file=stream)                       # doctest: +SKIP

        priority is the syslog priority, one of `LOG_EMERG`, `LOG_ALERT`,
        `LOG_CRIT`, `LOG_ERR`, `LOG_WARNING`, `LOG_NOTICE`, `LOG_INFO`, `LOG_DEBUG`.

        level_prefix is a boolean. If true, kernel-style log priority level prefixes
        (such as '<1>') are interpreted. See sd-daemon(3) for more information.
        """

        if identifier is None:
            if not _sys.argv or not _sys.argv[0] or _sys.argv[0] == '-c':
                identifier = 'python'
            else:
                identifier = _sys.argv[0]

        fd = stream_fd(identifier, priority, level_prefix)
        return _os.fdopen(fd, 'w', 1)

    class JournalHandler(_logging.Handler):
        """Journal handler class for the Python logging framework.

        Please see the Python logging module documentation for an overview:
        http://docs.python.org/library/logging.html.

        To create a custom logger whose messages go only to journal:

        >>> import logging
        >>> log = logging.getLogger('custom_logger_name')
        >>> log.propagate = False
        >>> log.addHandler(JournalHandler())
        >>> log.warning("Some message: %s", 'detail')

        Note that by default, message levels `INFO` and `DEBUG` are ignored by the
        logging framework. To enable those log levels:

        >>> log.setLevel(logging.DEBUG)

        To redirect all logging messages to journal regardless of where they come
        from, attach it to the root logger:

        >>> logging.root.addHandler(JournalHandler())

        For more complex configurations when using `dictConfig` or `fileConfig`,
        specify `systemd.journal.JournalHandler` as the handler class.  Only
        standard handler configuration options are supported: `level`, `formatter`,
        `filters`.

        To attach journal MESSAGE_ID, an extra field is supported:

        >>> import uuid
        >>> mid = uuid.UUID('0123456789ABCDEF0123456789ABCDEF')
        >>> log.warning("Message with ID", extra={'MESSAGE_ID': mid})

        Fields to be attached to all messages sent through this handler can be
        specified as keyword arguments. This probably makes sense only for
        SYSLOG_IDENTIFIER and similar fields which are constant for the whole
        program:

        >>> JournalHandler(SYSLOG_IDENTIFIER='my-cool-app')
        <...JournalHandler ...>

        The following journal fields will be sent: `MESSAGE`, `PRIORITY`,
        `THREAD_NAME`, `CODE_FILE`, `CODE_LINE`, `CODE_FUNC`, `LOGGER` (name as
        supplied to getLogger call), `MESSAGE_ID` (optional, see above),
        `SYSLOG_IDENTIFIER` (defaults to sys.argv[0]).

        The function used to actually send messages can be overridden using
        the `sender_function` parameter.
        """

        def __init__(self, level=_logging.NOTSET, sender_function=send, **kwargs):
            super(JournalHandler, self).__init__(level)

            for name in kwargs:
                if not _valid_field_name(name):
                    raise ValueError('Invalid field name: ' + name)
            if 'SYSLOG_IDENTIFIER' not in kwargs:
                kwargs['SYSLOG_IDENTIFIER'] = _sys.argv[0]

            self.send = sender_function
            self._extra = kwargs

        @classmethod
        def with_args(cls, config=None):
            """Create a JournalHandler with a configuration dictionary

            This creates a JournalHandler instance, but accepts the parameters through
            a dictionary that can be specified as a positional argument. This is useful
            in contexts like logging.config.fileConfig, where the syntax does not allow
            for positional arguments.

            >>> JournalHandler.with_args({'SYSLOG_IDENTIFIER':'my-cool-app'})
            <...JournalHandler ...>
            """
            return cls(**(config or {}))

        def emit(self, record):
            """Write `record` as a journal event.

            MESSAGE is taken from the message provided by the user, and PRIORITY,
            LOGGER, THREAD_NAME, CODE_{FILE,LINE,FUNC} fields are appended
            automatically. In addition, record.MESSAGE_ID will be used if present.
            """
            try:
                msg = self.format(record)
                pri = self.map_priority(record.levelno)
                # defaults
                extras = self._extra.copy()

                # higher priority
                if record.exc_text:
                    extras['EXCEPTION_TEXT'] = record.exc_text

                if record.exc_info:
                    extras['EXCEPTION_INFO'] = record.exc_info

                if record.args:
                    extras['CODE_ARGS'] = str(record.args)

                # explicit arguments — highest priority
                extras.update(record.__dict__)

                self.send(msg,
                          PRIORITY=format(pri),
                          LOGGER=record.name,
                          THREAD_NAME=record.threadName,
                          PROCESS_NAME=record.processName,
                          CODE_FILE=record.pathname,
                          CODE_LINE=record.lineno,
                          CODE_FUNC=record.funcName,
                          **extras)
            except Exception:
                self.handleError(record)

        @staticmethod
        def map_priority(levelno):
            """Map logging levels to journald priorities.

            Since Python log level numbers are "sparse", we have to map numbers in
            between the standard levels too.
            """
            if levelno <= _logging.DEBUG:
                return LOG_DEBUG
            elif levelno <= _logging.INFO:
                return LOG_INFO
            elif levelno <= _logging.WARNING:
                return LOG_WARNING
            elif levelno <= _logging.ERROR:
                return LOG_ERR
            elif levelno <= _logging.CRITICAL:
                return LOG_CRIT
            else:
                return LOG_ALERT

        mapPriority = map_priority