How to log to journald (systemd) via Python?

Question

I would like logging.info() to go to journald (systemd).

Up to now I only found python modules which read journald (not what I want) or modules which work like this: journal.send('Hello world')

Answer 1

python-systemd has a JournalHandler you can use with the logging framework.

From the documentation:

import logging
from systemd.journal import JournalHandler

log = logging.getLogger('demo')
log.addHandler(JournalHandler())
log.setLevel(logging.INFO)
log.info("sent to journal")

Answer 2

An alternative to the official package, the systemd package works with python 3.6. Its source is also on github.

The implementation is a mirror of the official lib, with some minor changes:

import logging
from systemd import journal

log = logging.getLogger('demo')
log.addHandler(journal.JournaldLogHandler())
log.setLevel(logging.INFO)
log.info("sent to journal")

or for an even shorter method:

from systemd import journal

journal.write("Hello Lennart")

Answer 3

This is a solution without third party modules. It works fine for me and the messages show up in journald.

import logging
import sys

logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)

# this is just to make the output look nice
formatter = logging.Formatter(fmt="%(asctime)s %(name)s.%(levelname)s: %(message)s", datefmt="%Y.%m.%d %H:%M:%S")

# this logs to stdout and I think it is flushed immediately
handler = logging.StreamHandler(stream=sys.stdout)
handler.setFormatter(formatter)
logger.addHandler(handler)

logger.info('test')