added code and readme contents

This commit is contained in:
Daniil Fajnberg 2022-02-02 12:03:45 +01:00
parent fc29d44522
commit 45a0e123fd
5 changed files with 169 additions and 3 deletions

View File

@ -1,10 +1,56 @@
# syslogformat
Python logging.Formatter class for syslog style messages
Python `logging.Formatter` class for syslog style messages
## Usage
...
Example with in-code setup:
```python
# example.py
import logging
from syslogformat import SyslogFormatter
log = logging.getLogger()
hdl = logging.StreamHandler()
fmt = SyslogFormatter()
hdl.setFormatter(fmt)
hdl.setLevel(logging.NOTSET)
log.addHandler(hdl)
log.setLevel(logging.NOTSET)
log.debug("foo")
log.info("bar")
log.warning("baz")
try:
raise ValueError("this is bad")
except ValueError as e:
log.exception("oh no")
```
This is what the output should be like:
```
<7>DEBUG | foo
<6>INFO | bar
<4>WARNING | baz | example.<module>.14
<3>ERROR | oh no | example.<module>.18 | 'Traceback (most recent call last):\n File "/path/to/example.py", line 16, in <module>\n raise ValueError("this is bad")\nValueError: this is bad'
```
Same configuration with YAML file to be loaded into `logging.config.dictConfig`:
```yaml
version: 1
formatters:
custom:
(): syslogformat.SyslogFormatter
handlers:
console:
class: logging.StreamHandler
level: NOTSET
formatter: custom
stream: ext://sys.stdout
root:
level: NOTSET
handlers: [console]
```
## Installation
@ -12,7 +58,7 @@ Python logging.Formatter class for syslog style messages
## Dependencies
Python Version ..., OS ...
Python Version 3
## Building from source

View File

@ -0,0 +1 @@
from syslogformat.formatter import SyslogFormatter

View File

@ -0,0 +1,65 @@
import logging as _logging
from syslogformat.helpers import check_level, py_to_sys_lvl
class SyslogFormatter(_logging.Formatter):
"""
logging.Formatter subclass for doing three things:
1) Format exception log messages into one-liners,
2) prepend a syslog oriented log level number to be recognized by systemd, and
3) append more details ([module].[function].[line]) to every message, when specified level is exceeded.
"""
def __init__(self, *args, **kwargs):
self.detail_threshold = check_level(kwargs.pop('detail_threshold', _logging.WARNING))
self.prepend_lvl_name = check_level(kwargs.pop('prepend_lvl_name', True))
super().__init__(*args, **kwargs)
def formatException(self, exc_info) -> str:
"""Format an exception so that it prints on a single line."""
return repr(super().formatException(exc_info))
def format(self, record: _logging.LogRecord) -> str:
"""
Format to be compatible with syslog levels and replace the newlines.
The entire message format is hard-coded here, so no format needs to be specified in the usual config.
"""
record.message = record.getMessage()
# Prepend syslog level depending on record level
s = f"<{py_to_sys_lvl(record.levelno)}>"
if self.prepend_lvl_name:
s += f"{record.levelname:<8} | "
s += self.formatMessage(record)
# If record level exceeds the threshold, append additional details
if record.levelno >= self.detail_threshold:
s += f" | {record.module}.{record.funcName}.{record.lineno}"
if record.exc_info and not record.exc_text:
record.exc_text = self.formatException(record.exc_info)
if record.exc_text:
s += ' | ' + record.exc_text
if record.stack_info:
s += self.formatStack(record.stack_info)
# Reformat exception line
return s.replace("\n", "")
if __name__ == '__main__':
log = _logging.getLogger()
hdl = _logging.StreamHandler()
fmt = SyslogFormatter()
hdl.setFormatter(fmt)
log.addHandler(hdl)
log.setLevel(_logging.NOTSET)
log.debug("foo")
log.info("bar")
log.warning("baz")
try:
raise ValueError("this is bad")
except ValueError as e:
log.exception("oh no")

View File

@ -0,0 +1,54 @@
import logging as _logging
from syslog import LOG_ALERT, LOG_CRIT, LOG_ERR, LOG_WARNING, LOG_INFO, LOG_DEBUG
from typing import Union
LevelT = Union[str, int]
def check_level(level: LevelT) -> int:
"""
Custom implementation of the logging module's _checkLevel(...) function.
Returns the numeric representation of a log level.
Args:
level: Either a string such as 'DEBUG' or 'WARNING' or an integer.
Returns:
If an integer is passed, it is returned unchanged;
if a string is passed, the corresponding numeric log level is returned.
Raises:
TypeError if something other than a string or an integer is passed.
ValueError if the string has no corresponding level in the logging module.
"""
if isinstance(level, int):
return level
if str(level) != level:
raise TypeError(f"Level not an integer or a valid string: {level}")
output = getattr(_logging, level)
if output is None:
raise ValueError(f"Unknown level: {level}")
return output
def py_to_sys_lvl(level_num: int) -> int:
"""
Maps a (numeric) log level as defined in Python stdlib logging module to the syslog module's log levels.
The output number corresponds to a syslog `PRI` without the enclosing angle brackets.
Even though there are more levels available to syslog, the `EMERG` (num. 0) and `NOTICE` (num. 5) levels are
omitted here, i.e. it goes straight from `INFO` (num. 6) to `WARNING` (num. 4) because there is no equivalent
in the Python logging module to `NOTICE`, and `EMERG` is unnecessary because no Python script should be able to
cause such severe problems.
"""
if level_num <= _logging.DEBUG:
return LOG_DEBUG
if level_num <= _logging.INFO:
return LOG_INFO
if level_num <= _logging.WARNING:
return LOG_WARNING
if level_num <= _logging.ERROR:
return LOG_ERR
if level_num <= _logging.CRITICAL:
return LOG_CRIT
return LOG_ALERT