Logging Levels

System logger

$ journalctl --unit=service

$ journalctl -fu service # To follow log as with tail -f

 
To limit journal logging:

$ sudo nano /etc/systemd/journald.conf
Uncomment
SystemMaxUse=100M
sudo systemctl restart systemd-journald

$ journalctl --disk-usage # How much space is used

Restart system logging
$ sudo systemctl restart rsyslog # resets /var/log/syslog, deamong.log
$ sudo systemctl restart logrotate

/usr/sbin/logrotate -f /etc/logrotate.d/spaikon # Force run logrotate

Show detailed debug trace
from loguru import logger
@logger.catch # Stack trace

Python logger

When a logger is created, the level is set to NOTSET (which causes all messages to be processed when the logger is the root logger, or delegation to the parent when the logger is a non-root logger).


Note that the root logger is created with level WARNING.

Level	Numeric value
CRITICAL	50
ERROR	40
WARNING	30
INFO	20
DEBUG	10
NOTSET	0

Documentation:

https://docs.python.org/3/howto/logging.html

Java spring logging

The available logging levels in Logback are:

OFF (output no logs)

ERROR

WARN

INFO

DEBUG

TRACE

Loging messeage meanings:

LOGGER.trace("doStuff needed more information - {}", value);

LOGGER.debug("doStuff needed to debug - {}", value);

LOGGER.info("doStuff took input - {}", value);

LOGGER.warn("doStuff needed to warn - {}", value);

LOGGER.error("doStuff encountered an error with value - {}", value);

To disable dublicating log code to log, add to logback.xml:

additivity="false"

Adding logger like:

private static final Logger log = LoggerFactory.getLogger(YourClassName.class);

Sources:

https://www.codingame.com/playgrounds/4497/configuring-logback-with-spring-boot

https://mkyong.com/logging/logback-duplicate-log-messages/

python logging

Adds logger to usual projects:

logging.getLogger('flask_cors').level = logging.DEBUG

Logging to file for paramiko library

logging.getLogger('paramiko').setLevel(logging.DEBUG)
paramiko.util.log_to_file('foo.log')