Originally written for Mandrill (screw them), this script can send an email alert, for example, when a remote job fails or some other unexpected event happens: I'm using it on my QNAP TS-212 NAS to alert me about backup jobs failures and other abnormal events.

alert

#!/bin/bash
#
# Failure reporter, logs to a well-known log file failure messages
#
# Created 2014-04-30, M. Massenzio ([email protected])

declare -r LOGFILE="/var/log/fail.log"
declare -r ALERT_ICON="/usr/share/icons/ubudao-style/actions/dialog-warning.png"
declare -r ERROR_ICON="/usr/share/icons/ubudao-style/actions/stock_dialog-error.png"

echo "[ERROR] `date` -- $1" >> ${LOGFILE}

notify-send -i ${ALERT_ICON} "Failure Alert" "$1"

alert.py -f ${HOME}/.yagmail -m "$1" -s "Failure Alert from `hostname`" \
        -d [email protected] >> ${LOGFILE} 2>&1

if [ $? != 0 ]; then
    echo "[ERROR] `date` -- Failed to send email alert" >> ${LOGFILE}
    notify-send -i ${ERROR_ICON} "Cannot Send Email" "Failed to send email alert, see log at ${LOGFILE}"
fi

alert.py

#!/usr/bin/env python
#
# Copyright AlertAvert.com (c) 2016. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Created by M. Massenzio ([email protected]), 2016-05-14

import argparse
import logging
import socket

# See: https://github.com/kootenpv/yagmail
import yagmail


FORMAT = '%(asctime)-15s [%(levelname)s] %(message)s'
DATE_FMT = '%m/%d/%Y %H:%M:%S'


def parse_args():
    """ Parse command line arguments and returns a configuration object
    """
    parser = argparse.ArgumentParser()
    parser.add_argument('-f', '--api-key-file', required=True,
                        help="The file containing the API key")
    parser.add_argument('-m', dest='msg', required=True, help="The body of the message")
    parser.add_argument('-d', dest='dest', help="The recipient of the email")
    parser.add_argument('-s', dest='subject', help='The subject for the email',
                        default='Alert from {hostname}'.format(hostname=socket.gethostname()))
    parser.add_argument('-v', dest='verbose', action='store_true', help='Enables debug logging')
    return parser.parse_args()


def post_mail(to, subj, msg, **kwargs):
    """ Sends the ``msg`` via email to the specified recipient.

        @param to: the recipient for the message
        @type to: str

        @param subj: the subject for the email
        @type subj: str

        @param msg: the body of the message, in plain text
        @type msg: str

        @see: https://github.com/kootenpv/yagmail
    """
    contents = """<h3>Automated Alert</h3>
                  <p>{msg}</p>
                  <h6>Sent via yagmail, using alert.py &copy; 2016 M. Massenzio, all rights reserved.<br>
                      See: https://github.com/kootenpv/yagmail</h6>
               """.format(msg=msg)
    with yagmail.SMTP(kwargs.get('username'), kwargs.get('api_key')) as yag:
        yag.send(to, subj, contents)
    logging.info('Message "{subj}" sent to {to}'.format(to=to, subj=subj))


def read_api_key(filename):
    with open(filename, 'r') as key_file:
        username = key_file.readline().rstrip('\n')
        api_key = key_file.readline().rstrip('\n')
    return {'username': username, 'api_key': api_key}


def main():
    config = parse_args()
    loglevel = logging.DEBUG if config.verbose else logging.INFO
    logging.basicConfig(format=FORMAT, datefmt=DATE_FMT, level=loglevel)
    logging.info('Mailer Auto Script starting...')
    try:
        kwargs = read_api_key(config.api_key_file)
    except Exception as ex:
        logging.error("Could not read the API Key ({}), aborting", ex)
        return
    logging.debug('API key retrieved')
    post_mail(to=config.dest, msg=config.msg, subj=config.subject, **kwargs)


if __name__ == "__main__":
    main()

alert.rst

Email Alerts via Yagmail API

Author:	Marco Massenzio
Date:	2016-05-14
Version:	0.2

Overview

This script sends an email alert to the specified recipient.

Usage

[~] # ./alert.py -f ./.secret -m "This is a test" -d [email protected] -s "Test Test Test" -v

For a full explanation of the command-line options run with --help.

Note with the --verbose option specified, the API key will be logged to stdout (typically, console): don't do this unless you run this in a trusted environment.

For more details, please see my blog entry or the yagmail documentation

check_boot.py

#!/usr/bin/env python
#
# Checks for remaining space in /boot and alerts if above a threshold.
# The threshold above which to alert can be passed in as the first CLI argument,
# or the default value will be used.
#
# Created by M. Massenzio, 2017-03-29

from sh import df, alert
import sys

threshold = 70
if len(sys.argv) > 1:
    try:
        threshold = int(sys.argv[1])
    except:
        alert("Program option should be a numeric value (threshold % above which to alert). "
              "Was: {}".format(sys.argv[1]))
        exit(1)

disk_space = df("-h")

for line in disk_space.split('\n'):
    if line.endswith('/boot'):
        items = line.split()
        use_pct = items[-2]
        assert use_pct.endswith('%')
        used_space = int(use_pct[:-1])
        if used_space > threshold:
            alert("/boot is running out of space: {} used`({} bytes left)".format(use_pct, items[-3]))
        exit(0)

# If we got here, we didn't find the /boot partition mount.
alert("Could not find the /boot partition, running `df`:\n{}".format(disk_space))
exit(1)