Cantemo logging¶
By default, Cantemo comes with built in logging to syslog. The log level can be configured in System Settings under the Admin menu.
Advanced configuration¶
For more advanced configuration, a specific logging configuration can be added to the file /etc/cantemo/portal/logging.conf which will override the settings made in the System Settings.
Cantemo uses the standard Python logging module, with an external configuration file that can configure the logging in multiple ways.
Please see the Python logging documentation or for the relevant documentation for your version of python for more information. This documentation also gives in depth knowledge of the logging module with regards to the components: loggers, handlers, filters and formatters. The information contained below is a primer with regards to logging with Cantemo.
Log levels¶
We log to several different levels, with the most sparse being provided at CRITICAL, and the most verbose being DEBUG
DEBUG
INFO
WARNING
ERROR
CRITICAL
All external communication can be viewed at DEBUG level, though production servers shouldn’t have this turned on unless a problem is being tracked down.
Handlers¶
The logging module uses the concepts of Handlers that deal with the logs files and distribute them accordingly. Multiple handlers can be used at once, or different handlers for different log levels. The most interesting handlers are listed below.
- StreamHandler
This is the most basic logger, and will stream logging output to streams such as sys.stdout, sys.stderr or any other file like object.
- FileHandle
Based on StreamHandler, this logs to a file as given.
- WatchedFiler
For use on Unix and Linux systems which can deal with their own rotation of logs.
- RotatingFileHandler
For automatic rotating of logging files after they reach a particular filesize.
- TimedRotatingFileHandler
Supports rotation of disk log files at certain timed intervals.
- SocketHandler
Sends logging output to a network socket using TCP.
- SysLogHandler
Supports sending logging messages to a remote or local Unix syslog
- NTEventLogHandler
Supports sending logging messages to a local Windows NT, Windows 2000 or Windows XP event log. Requires an additional Win32 extension.
Please see the appropriate Python documentation
Choosing Handlers¶
The handler to be used depends on the configuration of your Cantemo System. These recipes should give an idea of how to configure logging.
- Development system local machine on Unix based operating system
Use RotatingFileHandler with a DEBUG level logging to /var/log/cantemo/portal
- Production system with multiple Python workers/threads on Unix/Linux
Use SysLogHandler with INFO level to /var/log/cantemo/portal
Example logging configurations¶
Example logging.conf file is provided in the at /opt/cantemo/portal/configs/logging.conf.sample
Rsyslog¶
During installation rsyslog should have been installed and configured. You may however change the configuration here /etc/rsyslog.d/99-portal.conf
After changing the config-file the logging daemon needs to be restarted:
sudo restart rsyslog
Notes¶
When using Gunicorn with multiple works and logging handlers such as the TimedRotatingFileHandler or the RotatingFileHandler you might experience that only one thread will log to the log file. Use the SysLogHandler instead.
Additional Logs.¶
In addition to these logs, the webserver that you use will also be doing logging. Our preferred configuration with Nginx will produce log files handled by Nginx as detailed in the Nginx configuration files.
