Logging with Vala

How to send messages to syslog using Vala:

// log.vala

public static void main() {

    // Application Name (called 'domain' in Gspeak)
    string application_name = "MyTestApplication";

    // Log message
    string message = "This is a test message";

    // Log level - set to "Warning"
    GLib.LogLevelFlags glib_level       = GLib.LogLevelFlags.LEVEL_WARNING;
    int                posix_level      = Posix.LOG_WARNING; 

    // Print to stderr, not syslog or another log
    GLib.log( application_name, glib_level, message );

    // Log to syslog using the posix bindings
    // Posix.LOG_PID and Posix.LOG_USER are defined by Posix, not me.
    Posix.openlog(application_name, Posix.LOG_PID, Posix.LOG_USER);
    Posix.syslog(posix_level, message);

    return;
}

Compile using valac --pkg posix log.vala

Logging in Python 3

Here is one way to set up proper logging in Python.

This sample script sends some messages to syslog and others to a different logfile based upon their priority.

#!/usr/bin/python3

# Import the Standard Library modules we need
import logging
import logging.handlers

def set_up_logging():

    # File handler for /var/log/some.log
    serverlog = logging.FileHandler('/var/log/some.log')
    serverlog.setLevel(logging.DEBUG)
    serverlog.setFormatter(logging.Formatter(
        '%(asctime)s %(pathname)s [%(process)d]: %(levelname)s %(message)s'))

    # Syslog handler
    syslog = logging.handlers.SysLogHandler(address='/dev/log')
    syslog.setLevel(logging.WARNING)
    syslog.setFormatter(logging.Formatter(
        '%(pathname)s [%(process)d]: %(levelname)s %(message)s'))

    # Combined logger used elsewhere in the script
    logger = logging.getLogger('wbs-server-log')
    logger.setLevel(logging.DEBUG)
    logger.addHandler(serverlog)
    logger.addHandler(syslog)

    return logger

logger = set_up_logging()
logger.debug('This message should go to the log file')
logger.info('So should this')
logger.warning('And this, too')