runtime logger handler selector

src/ahriman/application/ahriman.py

@@ -30,6 +30,7 @@ from ahriman.application import handlers
 from ahriman.core.util import enum_values
 from ahriman.models.action import Action
 from ahriman.models.build_status import BuildStatusEnum
+from ahriman.models.log_handler import LogHandler
 from ahriman.models.package_source import PackageSource
 from ahriman.models.sign_settings import SignSettings
 from ahriman.models.user_access import UserAccess
@@ -58,6 +59,7 @@ def _formatter(prog: str) -> argparse.HelpFormatter:
     return argparse.ArgumentDefaultsHelpFormatter(prog, width=120)
 
 
+# pylint: disable=too-many-statements
 def _parser() -> argparse.ArgumentParser:
     """
     command line parser generator
@@ -75,6 +77,9 @@ def _parser() -> argparse.ArgumentParser:
     parser.add_argument("--force", help="force run, remove file lock", action="store_true")
     parser.add_argument("-l", "--lock", help="lock file", type=Path,
                         default=Path(tempfile.gettempdir()) / "ahriman.lock")
+    parser.add_argument("--log-handler", help="explicit log handler specification. If none set, the handler will be "
+                                              "guessed from environment",
+                        type=LogHandler, choices=enum_values(LogHandler))
     parser.add_argument("--report", help="force enable or disable reporting to web service",
                         action=argparse.BooleanOptionalAction, default=True)
     parser.add_argument("-q", "--quiet", help="force disable any logging", action="store_true")

src/ahriman/application/handlers/handler.py

@@ -94,7 +94,8 @@ class Handler:
         """
         try:
             configuration = Configuration.from_path(args.configuration, architecture)
-            Log.load(configuration, quiet=args.quiet, report=args.report)
+            log_handler = Log.handler(args.log_handler)
+            Log.load(configuration, log_handler, quiet=args.quiet, report=args.report)
             with Lock(args, architecture, configuration):
                 cls.run(args, architecture, configuration, report=args.report, unsafe=args.unsafe)
             return True

src/ahriman/core/log/journal_handler.py

@@ -0,0 +1,47 @@
+#
+# Copyright (c) 2021-2023 ahriman team.
+#
+# This file is part of ahriman
+# (see https://github.com/arcan1s/ahriman).
+#
+# This program 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.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+from logging import NullHandler
+from typing import Any
+
+
+__all__ = ["JournalHandler"]
+
+
+class _JournalHandler(NullHandler):
+    """
+    wrapper for unexpected args and kwargs
+    """
+
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
+        """
+        default constructor
+
+        Args:
+            *args(Any): positional arguments
+            **kwargs(Any): keyword arguments
+        """
+        NullHandler.__init__(self)
+        del args, kwargs
+
+
+try:
+    from systemd.journal import JournalHandler  # type: ignore[import]
+except ImportError:
+    JournalHandler = _JournalHandler

src/ahriman/core/log/log.py

@@ -20,9 +20,11 @@
 import logging
 
 from logging.config import fileConfig
+from pathlib import Path
 
 from ahriman.core.configuration import Configuration
 from ahriman.core.log.http_log_handler import HttpLogHandler
+from ahriman.models.log_handler import LogHandler
 
 
 class Log:
@@ -32,24 +34,65 @@ class Log:
     Attributes:
         DEFAULT_LOG_FORMAT(str): (class attribute) default log format (in case of fallback)
         DEFAULT_LOG_LEVEL(int): (class attribute) default log level (in case of fallback)
+        DEFAULT_SYSLOG_DEVICE(Path): (class attribute) default path to syslog device
     """
 
     DEFAULT_LOG_FORMAT = "[%(levelname)s %(asctime)s] [%(filename)s:%(lineno)d %(funcName)s]: %(message)s"
     DEFAULT_LOG_LEVEL = logging.DEBUG
+    DEFAULT_SYSLOG_DEVICE = Path("/dev") / "log"
 
     @staticmethod
-    def load(configuration: Configuration, *, quiet: bool, report: bool) -> None:
+    def handler(selected: LogHandler | None) -> LogHandler:
+        """
+        try to guess default log handler. In case if ``selected`` is set, it will return specified value with appended
+        _handler suffix. Otherwise, it will try to import journald handler and returns ``journald_handler`` if library
+        is available. Otherwise, it will check if there is ``/dev/log`` device and returns ``syslog_handler`` in this
+        case. And, finally, it will fall back to ``console_handler`` if none were found
+
+        Args:
+            selected(LogHandler | None): user specified handler if any
+
+        Returns:
+            LogHandler: selected log handler
+        """
+        if selected is not None:
+            return selected
+
+        try:
+            from systemd.journal import JournalHandler  # type: ignore[import]
+            del JournalHandler
+            return LogHandler.Journald  # journald import was found
+        except ImportError:
+            if Log.DEFAULT_SYSLOG_DEVICE.exists():
+                return LogHandler.Syslog
+            return LogHandler.Console
+
+    @staticmethod
+    def load(configuration: Configuration, handler: LogHandler, *, quiet: bool, report: bool) -> None:
         """
         setup logging settings from configuration
 
         Args:
             configuration(Configuration): configuration instance
+            handler(LogHandler): selected default log handler, which will be used if no handlers were set
             quiet(bool): force disable any log messages
             report(bool): force enable or disable reporting
         """
+        default_handler = f"{handler.value}_handler"
+
         try:
-            path = configuration.logging_path
-            fileConfig(path)
+            log_configuration = Configuration()
+            log_configuration.read(configuration.logging_path)
+
+            # set handlers if they are not set
+            for section in filter(lambda s: s.startswith("logger_"), log_configuration.sections()):
+                if "handlers" in log_configuration[section]:
+                    continue
+                log_configuration.set_option(section, "handlers", default_handler)
+
+            # load logging configuration
+            fileConfig(log_configuration, disable_existing_loggers=True)
+            logging.debug("using %s logger", default_handler)
         except Exception:
             logging.basicConfig(filename=None, format=Log.DEFAULT_LOG_FORMAT,
                                 level=Log.DEFAULT_LOG_LEVEL)

src/ahriman/models/log_handler.py

@@ -0,0 +1,35 @@
+#
+# Copyright (c) 2021-2023 ahriman team.
+#
+# This file is part of ahriman
+# (see https://github.com/arcan1s/ahriman).
+#
+# This program 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.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+from enum import Enum
+
+
+class LogHandler(str, Enum):
+    """
+    log handler as described by default configuration
+
+    Attributes:
+        Console(LogHandler): (class attribute) write logs to console
+        Syslog(LogHandler): (class attribute) write logs to syslog device /dev/null
+        Journald(LogHandler): (class attribute) write logs to journald directly
+    """
+
+    Console = "console"
+    Syslog = "syslog"
+    Journald = "journald"