{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Logging examples"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Creating a log file"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "WARNING:root:This is a warning message\n",
      "CRITICAL:root:This is a critical message\n"
     ]
    }
   ],
   "source": [
    "import logging\n",
    "\n",
    "\n",
    "logging.warning(\"This is a warning message\")\n",
    "logging.critical(\"This is a critical message\")\n",
    "logging.debug(\"debug\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Logging levels\n",
    "\n",
    "Level | Description\n",
    ":-- | :--\n",
    "``CRITICAL`` | The programme was stopped\n",
    "``ERROR`` | A serious error has occurred\n",
    "``WARNING`` | An indication that something unexpected has happened (default level)\n",
    "``INFO`` | Confirmation that things are working as expected\n",
    "``DEBUG`` | Detailed information that is usually only of interest when diagnosing problems"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Setting the logging level"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "ERROR:root:An error has happened!\n"
     ]
    }
   ],
   "source": [
    "import logging\n",
    "\n",
    "\n",
    "logging.basicConfig(filename=\"example.log\", filemode=\"w\", level=logging.INFO)\n",
    "\n",
    "logging.info(\"Informational message\")\n",
    "logging.error(\"An error has happened!\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Creating a Logger Object"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "ERROR:example:Error!\n",
      "Traceback (most recent call last):\n",
      "  File \"/var/folders/hk/s8m0bblj0g10hw885gld52mc0000gn/T/ipykernel_14074/2646645271.py\", line 9, in <module>\n",
      "    raise RuntimeError\n",
      "RuntimeError\n"
     ]
    }
   ],
   "source": [
    "import logging\n",
    "\n",
    "\n",
    "logging.basicConfig(filename=\"example.log\")\n",
    "logger = logging.getLogger(\"example\")\n",
    "logger.setLevel(logging.INFO)\n",
    "\n",
    "try:\n",
    "    raise RuntimeError\n",
    "except Exception:\n",
    "    logger.exception(\"Error!\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Logging exceptions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "ERROR:example:You can’t do that!\n",
      "Traceback (most recent call last):\n",
      "  File \"/var/folders/hk/s8m0bblj0g10hw885gld52mc0000gn/T/ipykernel_14074/760044062.py\", line 2, in <module>\n",
      "    1 / 0\n",
      "    ~~^~~\n",
      "ZeroDivisionError: division by zero\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    1 / 0\n",
    "except ZeroDivisionError:\n",
    "    logger.exception(\"You can’t do that!\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Logging handler\n",
    "\n",
    "### Handler types\n",
    "\n",
    "Handler | Description\n",
    ":--- | :---\n",
    "``StreamHandler`` | ``stdout``, ``stderr`` or file-like objects\n",
    "``FileHandler`` | for writing to disk\n",
    "``RotatingFileHandler`` | supports log rotation\n",
    "``TimedRotatingFileHandler`` | supports the rotation of log files on the hard disk at specific time intervals\n",
    "``SocketHandler`` | sends logging output to a network socket\n",
    "``SMTPHandler`` | supports sending logging messages to an e-mail address via SMTP\n",
    "\n",
    "<div class=\"alert alert-block alert-info\">\n",
    "\n",
    "**See also:**\n",
    "\n",
    "Further handlers can be found at [Logging handlers](https://docs.python.org/3/library/logging.handlers.html#module-logging.handlers)\n",
    "</div>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### StreamHandler"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "This is an informational message\n",
      "INFO:stream_logger:This is an informational message\n"
     ]
    }
   ],
   "source": [
    "import logging\n",
    "\n",
    "\n",
    "logger = logging.getLogger(\"stream_logger\")\n",
    "logger.setLevel(logging.INFO)\n",
    "\n",
    "console = logging.StreamHandler()\n",
    "\n",
    "logger.addHandler(console)\n",
    "logger.info(\"This is an informational message\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### SMTPHandler"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "--- Logging error ---\n",
      "Traceback (most recent call last):\n",
      "  File \"/Users/veit/Library/Application Support/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/logging/handlers.py\", line 1087, in emit\n",
      "    smtp = smtplib.SMTP(self.mailhost, port, timeout=self.timeout)\n",
      "  File \"/Users/veit/Library/Application Support/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/smtplib.py\", line 255, in __init__\n",
      "    (code, msg) = self.connect(host, port)\n",
      "                  ~~~~~~~~~~~~^^^^^^^^^^^^\n",
      "  File \"/Users/veit/Library/Application Support/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/smtplib.py\", line 341, in connect\n",
      "    self.sock = self._get_socket(host, port, self.timeout)\n",
      "                ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^\n",
      "  File \"/Users/veit/Library/Application Support/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/smtplib.py\", line 312, in _get_socket\n",
      "    return socket.create_connection((host, port), timeout,\n",
      "           ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^\n",
      "                                    self.source_address)\n",
      "                                    ^^^^^^^^^^^^^^^^^^^^\n",
      "  File \"/Users/veit/Library/Application Support/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/socket.py\", line 864, in create_connection\n",
      "    raise exceptions[0]\n",
      "  File \"/Users/veit/Library/Application Support/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/socket.py\", line 849, in create_connection\n",
      "    sock.connect(sa)\n",
      "    ~~~~~~~~~~~~^^^^\n",
      "ConnectionRefusedError: [Errno 61] Connection refused\n",
      "Call stack:\n",
      "  File \"<frozen runpy>\", line 198, in _run_module_as_main\n",
      "  File \"<frozen runpy>\", line 88, in _run_code\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/ipykernel_launcher.py\", line 18, in <module>\n",
      "    app.launch_new_instance()\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/traitlets/config/application.py\", line 1075, in launch_instance\n",
      "    app.start()\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/ipykernel/kernelapp.py\", line 739, in start\n",
      "    self.io_loop.start()\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/tornado/platform/asyncio.py\", line 205, in start\n",
      "    self.asyncio_loop.run_forever()\n",
      "  File \"/Users/veit/Library/Application Support/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/asyncio/base_events.py\", line 679, in run_forever\n",
      "    self._run_once()\n",
      "  File \"/Users/veit/Library/Application Support/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/asyncio/base_events.py\", line 2027, in _run_once\n",
      "    handle._run()\n",
      "  File \"/Users/veit/Library/Application Support/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/asyncio/events.py\", line 89, in _run\n",
      "    self._context.run(self._callback, *self._args)\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/ipykernel/kernelbase.py\", line 545, in dispatch_queue\n",
      "    await self.process_one()\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/ipykernel/kernelbase.py\", line 534, in process_one\n",
      "    await dispatch(*args)\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/ipykernel/kernelbase.py\", line 437, in dispatch_shell\n",
      "    await result\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/ipykernel/ipkernel.py\", line 362, in execute_request\n",
      "    await super().execute_request(stream, ident, parent)\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/ipykernel/kernelbase.py\", line 778, in execute_request\n",
      "    reply_content = await reply_content\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/ipykernel/ipkernel.py\", line 449, in do_execute\n",
      "    res = shell.run_cell(\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/ipykernel/zmqshell.py\", line 549, in run_cell\n",
      "    return super().run_cell(*args, **kwargs)\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/IPython/core/interactiveshell.py\", line 3075, in run_cell\n",
      "    result = self._run_cell(\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/IPython/core/interactiveshell.py\", line 3130, in _run_cell\n",
      "    result = runner(coro)\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/IPython/core/async_helpers.py\", line 128, in _pseudo_sync_runner\n",
      "    coro.send(None)\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/IPython/core/interactiveshell.py\", line 3334, in run_cell_async\n",
      "    has_raised = await self.run_ast_nodes(code_ast.body, cell_name,\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/IPython/core/interactiveshell.py\", line 3517, in run_ast_nodes\n",
      "    if await self.run_code(code, result, async_=asy):\n",
      "  File \"/Users/veit/cusy/trn/jupyter-tutorial/uvenvs/py313/.venv/lib/python3.13/site-packages/IPython/core/interactiveshell.py\", line 3577, in run_code\n",
      "    exec(code_obj, self.user_global_ns, self.user_ns)\n",
      "  File \"/var/folders/hk/s8m0bblj0g10hw885gld52mc0000gn/T/ipykernel_14074/3660210047.py\", line 14, in <module>\n",
      "    logger.info(\"This is an informational message\")\n",
      "Message: 'This is an informational message'\n",
      "Arguments: ()\n",
      "INFO:email_logger:This is an informational message\n"
     ]
    }
   ],
   "source": [
    "import logging\n",
    "import logging.handlers\n",
    "\n",
    "\n",
    "logger = logging.getLogger(\"email_logger\")\n",
    "logger.setLevel(logging.INFO)\n",
    "fh = logging.handlers.SMTPHandler(\n",
    "    \"localhost\",\n",
    "    fromaddr=\"python-log@localhost\",\n",
    "    toaddrs=[\"logs@cusy.io\"],\n",
    "    subject=\"Python log\",\n",
    ")\n",
    "logger.addHandler(fh)\n",
    "logger.info(\"This is an informational message\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Log formatting\n",
    "\n",
    "You can use formatters to format log messages."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "formatter = logging.Formatter(\"%(asctime)s - %(name)s - %(message)s\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Besides ``%(asctime)s``, ``%(name)s`` and ``%(message)s`` you will find other attributes in [LogRecord attributes](https://docs.python.org/3/library/logging.html#logrecord-attributes)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "This is an informational message\n",
      "2024-11-03 16:40:42,349 - stream_logger - This is an informational message\n",
      "INFO:stream_logger:This is an informational message\n"
     ]
    }
   ],
   "source": [
    "import logging\n",
    "\n",
    "\n",
    "logger = logging.getLogger(\"stream_logger\")\n",
    "logger.setLevel(logging.INFO)\n",
    "\n",
    "console = logging.StreamHandler()\n",
    "formatter = logging.Formatter(\"%(asctime)s - %(name)s - %(message)s\")\n",
    "console.setFormatter(formatter)\n",
    "\n",
    "logger.addHandler(console)\n",
    "logger.info(\"This is an informational message\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<div class=\"alert alert-block alert-info\">\n",
    "\n",
    "**Note:**\n",
    "\n",
    "The logging module is thread-safe. However, logging may not work in asynchronous contexts. In such cases, however, you can use the [QueueHandler](https://docs.python.org/3/library/logging.handlers.html#queuehandler).\n",
    "</div>\n",
    "<div class=\"alert alert-block alert-info\">\n",
    "\n",
    "**See also:**\n",
    "\n",
    "[Logging to a single file from multiple processes](https://docs.python.org/3/howto/logging-cookbook.html#logging-to-a-single-file-from-multiple-processes)\n",
    "</div>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Logging to multiple handlers"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [],
   "source": [
    "import logging\n",
    "\n",
    "\n",
    "def log(path, multipleLocs=False):\n",
    "    logger = logging.getLogger(\"Example_logger_%s\" % fname)\n",
    "    logger.setLevel(logging.INFO)\n",
    "    fh = logging.FileHandler(path)\n",
    "    formatter = logging.Formatter(\"%(asctime)s - %(name)s - %(message)s\")\n",
    "    fh.setFormatter(formatter)\n",
    "    logger.addHandler(fh)\n",
    "\n",
    "    if multipleLocs:\n",
    "        console = logging.StreamHandler()\n",
    "        console.setLevel(logging.INFO)\n",
    "        console.setFormatter(formatter)\n",
    "        logger.addHandler(console)\n",
    "\n",
    "    logger.info(\"This is an informational message\")\n",
    "    try:\n",
    "        1 / 0\n",
    "    except ZeroDivisionError:\n",
    "        logger.exception(\"You can’t do that!\")\n",
    "\n",
    "    logger.critical(\"This is a no-brainer!\")                                                                                                                     "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Configure logging\n",
    "\n",
    "<div class=\"alert alert-block alert-info\">\n",
    "\n",
    "**See also:**\n",
    "\n",
    "* [logging configuration](https://docs.python.org/3/howto/logging.html#configuring-logging)\n",
    "</div>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### … in an INI file\n",
    "\n",
    "In the following example, the file `development.ini` is loaded in this directory:\n",
    "\n",
    "``` ini\n",
    "[loggers]\n",
    "keys=root\n",
    "\n",
    "[handlers]\n",
    "keys=stream_handler\n",
    "\n",
    "[formatters]\n",
    "keys=formatter\n",
    "\n",
    "[logger_root]\n",
    "level=DEBUG\n",
    "handlers=stream_handler\n",
    "\n",
    "[handler_stream_handler]\n",
    "class=StreamHandler\n",
    "level=DEBUG\n",
    "formatter=formatter\n",
    "args=(sys.stderr,)\n",
    "\n",
    "[formatter_formatter]\n",
    "format=%(asctime)s %(name)-12s %(levelname)-8s %(message)s\n",
    "```"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [],
   "source": [
    "import logging\n",
    "import logging.config\n",
    "\n",
    "from logging.config import fileConfig\n",
    "\n",
    "\n",
    "logging.config.fileConfig(\"development.ini\")\n",
    "logger = logging.getLogger(\"example\")\n",
    "\n",
    "logger.info(\"Program started\")\n",
    "logger.info(\"Done!\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Pro:**\n",
    "\n",
    "* Ability to update the configuration on the fly by using the `logging.config.listen()` function to listen on a socket.\n",
    "* Different configurations can be used in different environments, so for example, `DEBUG` can be specified as the log level in `development.ini`, while `WARN` is used in `production.ini`.\n",
    "\n",
    "**Con:**\n",
    "\n",
    "* Less control for example over custom filters or loggers configured in code."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### … in a `dict` config"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [],
   "source": [
    "import logging\n",
    "import logging.config\n",
    "\n",
    "\n",
    "dictLogConfig = {\n",
    "    \"version\": 1,\n",
    "    \"handlers\": {\n",
    "        \"fileHandler\": {\n",
    "            \"class\": \"logging.FileHandler\",\n",
    "            \"formatter\": \"exampleFormatter\",\n",
    "            \"filename\": \"dict_config.log\",\n",
    "        }\n",
    "    },\n",
    "    \"loggers\": {\n",
    "        \"exampleApp\": {\n",
    "            \"handlers\": [\"fileHandler\"],\n",
    "            \"level\": \"INFO\",\n",
    "        }\n",
    "    },\n",
    "    \"formatters\": {\n",
    "        \"exampleFormatter\": {\n",
    "            \"format\": \"%(asctime)s - %(name)s - %(levelname)s - %(message)s\"\n",
    "        }\n",
    "    },\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "2024-11-03 16:40:42,364 exampleApp   INFO     Program started\n",
      "2024-11-03 16:40:42,365 exampleApp   INFO     Done!\n"
     ]
    }
   ],
   "source": [
    "logging.config.dictConfig(dictLogConfig)\n",
    "\n",
    "logger = logging.getLogger(\"exampleApp\")\n",
    "\n",
    "logger.info(\"Program started\")\n",
    "logger.info(\"Done!\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Pro:**\n",
    "\n",
    "* Update on the fly\n",
    "\n",
    "**Con:**\n",
    "\n",
    "* Less control than configuring a logger in code"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### … directly in the code"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [],
   "source": [
    "logger = logging.getLogger()\n",
    "handler = logging.StreamHandler()\n",
    "formatter = logging.Formatter(\n",
    "    \"%(asctime)s %(name)-12s %(levelname)-8s %(message)s\"\n",
    ")\n",
    "handler.setFormatter(formatter)\n",
    "logger.addHandler(handler)\n",
    "logger.setLevel(logging.DEBUG)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## *Magic Commands*\n",
    "\n",
    "| Befehl         | Beschreibung                                                                              |\n",
    "| -------------- | ----------------------------------------------------------------------------------------- |\n",
    "| `%logstart`    | Starts logging anywhere in a session                                                      |\n",
    "|                | `%logstart [-o\\|-r\\|-t\\|-q] [log_name [log_mode]]`                                        |\n",
    "|                | If no name is given, `ipython_log.py` is used in the current directory.                   |\n",
    "|                | `log_mode` is an optional parameter. The following modes can be specified:                |\n",
    "|                | * `append` appends the logging information to the end of an existing file                 |\n",
    "|                | * `backup` renames the existing file to `name~` and writes to `name`                      |\n",
    "|                | * `global` appends the logging information at the end of an existing file                 |\n",
    "|                | * `over` overwrites an existing log file                                                  |\n",
    "|                | * `rotate` creates rotating log files: `name.1~`, `name.2~`, etc.                         |\n",
    "|                | Options:                                                                                  |\n",
    "|                | * `-o` also logs the output of IPython                                                    |\n",
    "|                | * `-r` logs raw output                                                                    |\n",
    "|                | * `-t` writes a time stamp in front of each log entry                                     |\n",
    "|                | * `-q` suppresses the logging output                                                      |\n",
    "| `%logon`       | Restart the logging                                                                       |\n",
    "| `%logoff`      | Temporary termination of logging                                                          |\n",
    "\n",
    "**Pro:**\n",
    "\n",
    "* Complete control over the configuration\n",
    "\n",
    "**Con:**\n",
    "\n",
    "* Changes in the configuration require a change in the source code"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Logs rotate"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "2024-11-03 16:40:42,370 Rotating Log INFO     This is an example log line 0\n",
      "2024-11-03 16:40:42,370 Rotating Log INFO     This is an example log line 0\n",
      "2024-11-03 16:40:43,876 Rotating Log INFO     This is an example log line 1\n",
      "2024-11-03 16:40:43,876 Rotating Log INFO     This is an example log line 1\n",
      "2024-11-03 16:40:45,384 Rotating Log INFO     This is an example log line 2\n",
      "2024-11-03 16:40:45,384 Rotating Log INFO     This is an example log line 2\n",
      "2024-11-03 16:40:46,893 Rotating Log INFO     This is an example log line 3\n",
      "2024-11-03 16:40:46,893 Rotating Log INFO     This is an example log line 3\n",
      "2024-11-03 16:40:48,399 Rotating Log INFO     This is an example log line 4\n",
      "2024-11-03 16:40:48,399 Rotating Log INFO     This is an example log line 4\n",
      "2024-11-03 16:40:49,908 Rotating Log INFO     This is an example log line 5\n",
      "2024-11-03 16:40:49,908 Rotating Log INFO     This is an example log line 5\n",
      "2024-11-03 16:40:51,414 Rotating Log INFO     This is an example log line 6\n",
      "2024-11-03 16:40:51,414 Rotating Log INFO     This is an example log line 6\n",
      "2024-11-03 16:40:52,922 Rotating Log INFO     This is an example log line 7\n",
      "2024-11-03 16:40:52,922 Rotating Log INFO     This is an example log line 7\n",
      "2024-11-03 16:40:54,428 Rotating Log INFO     This is an example log line 8\n",
      "2024-11-03 16:40:54,428 Rotating Log INFO     This is an example log line 8\n",
      "2024-11-03 16:40:55,938 Rotating Log INFO     This is an example log line 9\n",
      "2024-11-03 16:40:55,938 Rotating Log INFO     This is an example log line 9\n"
     ]
    }
   ],
   "source": [
    "import logging\n",
    "import time\n",
    "\n",
    "from logging.handlers import RotatingFileHandler\n",
    "\n",
    "\n",
    "def create_rotating_log(path):\n",
    "    logger = logging.getLogger(\"Rotating Log\")\n",
    "    logger.setLevel(logging.INFO)\n",
    "\n",
    "    handler = RotatingFileHandler(path, maxBytes=20, backupCount=5)\n",
    "    logger.addHandler(handler)\n",
    "\n",
    "    for i in range(10):\n",
    "        logger.info(f\"This is an example log line {i}\")\n",
    "        time.sleep(1.5)\n",
    "\n",
    "\n",
    "if __name__ == \"__main__\":\n",
    "    log_file = \"rotated.log\"\n",
    "    create_rotating_log(log_file)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Rotate logs time-controlled"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "2024-11-03 16:40:57,454 Rotating Log INFO     This is an example!\n",
      "2024-11-03 16:40:57,454 Rotating Log INFO     This is an example!\n"
     ]
    }
   ],
   "source": [
    "import logging\n",
    "import time\n",
    "\n",
    "from logging.handlers import TimedRotatingFileHandler\n",
    "\n",
    "\n",
    "def create_timed_rotating_log(path):\n",
    "    \"\"\"\"\"\"\n",
    "    logger = logging.getLogger(\"Rotating Log\")\n",
    "    logger.setLevel(logging.INFO)\n",
    "\n",
    "    handler = TimedRotatingFileHandler(\n",
    "        path, when=\"s\", interval=5, backupCount=5\n",
    "    )\n",
    "    logger.addHandler(handler)\n",
    "\n",
    "    for i in range(6):\n",
    "        logger.info(\"This is an example!\")\n",
    "        time.sleep(75)\n",
    "\n",
    "\n",
    "if __name__ == \"__main__\":\n",
    "    log_file = \"timed_rotation.log\"\n",
    "    create_timed_rotating_log(log_file)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Create a logging decorator\n",
    "\n",
    "<div class=\"alert alert-block alert-info\">\n",
    "\n",
    "**See also:**\n",
    "\n",
    "* [How to Create an Exception Logging Decorator](https://www.blog.pythonlibrary.org/2016/06/09/python-how-to-create-an-exception-logging-decorator/)\n",
    "</div>"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Create a logging filter"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import logging\n",
    "import sys\n",
    "\n",
    "\n",
    "class ExampleFilter(logging.Filter):\n",
    "    def filter(self, record):\n",
    "        if record.funcName == \"foo\":\n",
    "            return False\n",
    "        return True\n",
    "\n",
    "\n",
    "logger = logging.getLogger(\"filter_example\")\n",
    "logger.addFilter(ExampleFilter())\n",
    "\n",
    "\n",
    "def foo():\n",
    "    \"\"\"\n",
    "    Ignore this function’s log messages\n",
    "    \"\"\"\n",
    "    logger.debug(\"Message from function foo\")\n",
    "\n",
    "\n",
    "def bar():\n",
    "    logger.debug(\"Message from bar\")\n",
    "\n",
    "\n",
    "if __name__ == \"__main__\":\n",
    "    logging.basicConfig(stream=sys.stderr, level=logging.DEBUG)\n",
    "    foo()\n",
    "    bar()"
   ]
  }
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