Collate output in Python logging MemoryHandler with SMTPHandler

You might want to use or adapt the BufferingSMTPHandler which is in this test script.

In general, you don't need to add a handler to a logger if it's the target of a MemoryHandler handler which has been added to a logger. If you set the level of a handler, that will affect what the handler actually processes - it won't process anything which is less severe than its level setting.

Instead of buffering for email, consider posting unbuffered to a message stream on a messaging app, e.g. on Matrix, Discord, Slack, etc. Having said that, I wrote my own beastly thread-safe implementation of BufferingSMTPHandler (backup link) which sends emails from a separate thread. The primary goal is to not block the main thread.

As written, it uses two queues - this seemed necessary in order to implement some useful class-level parameters that are defined in the "Configurable parameters" section of the code. Although you can use the code as-is, it's probably better if you study and use it to write your own class.

Issues:

• Some class-level parameters can perhaps be instance-level instead.
• Either threading.Timer or the signal module could perhaps be used to avoid loops that run forever.

If you are using django - here is simple buffering handler, which will use standard django email methods:

import logging

from django.conf import settings
from django.core.mail import EmailMessage


class DjangoBufferingSMTPHandler(logging.handlers.BufferingHandler):
    def __init__(self, capacity, toaddrs=None, subject=None):
        logging.handlers.BufferingHandler.__init__(self, capacity)

        if toaddrs:
            self.toaddrs = toaddrs
        else:
            # Send messages to site administrators by default
            self.toaddrs = zip(*settings.ADMINS)[-1]

        if subject:
            self.subject = subject
        else:
            self.subject = 'logging'

    def flush(self):
        if len(self.buffer) == 0:
            return

        try:
            msg = "\r\n".join(map(self.format, self.buffer))
            emsg = EmailMessage(self.subject, msg, to=self.toaddrs)
            emsg.send()
        except Exception:
            # handleError() will print exception info to stderr if logging.raiseExceptions is True
            self.handleError(record=None)
        self.buffer = []

In django settings.py you will need to configure email and logging like this:

EMAIL_USE_TLS = True
EMAIL_PORT = 25  
EMAIL_HOST = ''  # example: 'smtp.yandex.ru'
EMAIL_HOST_USER = ''  # example: '[email protected]'
EMAIL_HOST_PASSWORD = ''
DEFAULT_FROM_EMAIL = EMAIL_HOST_USER
SERVER_EMAIL = EMAIL_HOST_USER

LOGGING = {
    'handlers': {
        ...
        'mail_buffer': {
            'level': 'WARN',
            'capacity': 9999,
            'class': 'utils.logging.DjangoBufferingSMTPHandler',
            # optional: 
            # 'toaddrs': '[email protected]'
            # 'subject': 'log messages'
        }
    },
    ...
}