This is a simple script implemented in Python 3 which pings host devices and sends a Slack notification if the device does not respond.
In data directory copy the data.py.sample file as data.py.
cp data/data.py.sample data/data.py
Set the variables as instructed in the comments. You need a Slack channel with an Incoming Webhooks integration installed on that channel.
This script will only work with hosts which allow ping.