mdadm notifications to Slack

docker-compose.yml

version: "3"
services:
  mdadm-monitor:
    container_name: mdadm-monitor
    build: mdadm-monitor
    privileged: true
    restart: always
    volumes:
      - /proc:/proc
      - /dev:/dev
      - ${PWD}/conf/mdadm-monitor/mdadm.conf:/etc/mdadm/mdadm.conf
    environment:
      SLACK_URL: https://hooks.slack.com/services/***/***/***

Dockerfile

FROM ubuntu:20.04

RUN apt-get update -y
RUN apt-get upgrade -y
RUN apt-get install -y mdadm python3-minimal ca-certificates

RUN mkdir /app
WORKDIR /app

ADD notify.py .
RUN chmod +x notify.py

CMD mdadm --monitor --scan

mdadm.conf

# mdadm.conf
#
# !NB! Run update-initramfs -u after updating this file.
# !NB! This will ensure that initramfs has an uptodate copy.
#
# Please refer to mdadm.conf(5) for information about this file.
#

# by default (built-in), scan all partitions (/proc/partitions) and all
# containers for MD superblocks. alternatively, specify devices to scan, using
# wildcards if desired.
#DEVICE partitions containers

# automatically tag new arrays as belonging to the local system
HOMEHOST <system>

# instruct the monitoring daemon how to send alerts
PROGRAM /app/notify.py

# definitions of existing MD arrays

# This configuration was auto-generated on Sun, 21 Apr 2019 15:54:55 +0100 by mkconf
ARRAY /dev/md/127_0 metadata=0.90 UUID=8167a3b7:fc362825:409a2900:8a49c38d

notify.py

#!/usr/bin/env python3
"""
Send notifications of mdadm events to Slack.
"""
import argparse
import json
import os
import subprocess
import sys
import urllib.request

SLACK_URL = os.environ['SLACK_URL']


def main():
    """
    Main program.
    """
    parser = argparse.ArgumentParser()
    parser.add_argument("event", help="Event")
    parser.add_argument("device", help="Device")
    parser.add_argument("component", help="Related component device", nargs="?")
    args = parser.parse_args()

    # Get mdadm detail
    proc = subprocess.run(["mdadm", "--detail", args.device],
                          stdout=subprocess.PIPE, stderr=subprocess.STDOUT, check=True)
    detail = proc.stdout.decode("utf8")

    # Notify slack
    data = {
        "attachments": [
            {
                "color": '#FF0000',
                "text": (f"❌ *mdadm: {args.event}* on *{args.device}*\n"
                         f"```{detail}```"),
            },
        ],
    }
    headers = {
        "Content-type": "application/json"
    }

    req = urllib.request.Request(SLACK_URL, data=json.dumps(data).encode("utf8"), headers=headers)
    with urllib.request.urlopen(req) as resp:
        pass

    if resp.status != 200:
        print(resp.status)
        sys.exit(1)


if __name__ == "__main__":
    main()