Memory low alert2slack

memory_low_alert2slack.sh

#!/bin/bash

LANG=C
MINIMUM_REQUIRED_MEM=256
FREE_MEM=$(free -mt | awk '/Total/{print $4}')

if [ $FREE_MEM -lt $MINIMUM_REQUIRED_MEM ]; then
  TOP_PROCESS=$(ps aux --sort rss | tail -n1)
  MESSAGE=$(echo "WARNING On $HOSTNAME, memory usage is low: $TOP_PROCESS WARNING" | sed 's/ /_/g')
  # Post message
  # @see https://api.slack.com/messaging/webhooks#create_a_webhook
  curl -X POST --data-urlencode \
    'payload={"channel": "#sitehealth", "username": "webhookbot", "text": "'$MESSAGE'", "icon_emoji": ":ghost:"}' \
    https://hooks.slack.com/services/YourHook
fi

If the system is really struggling, the script might not be able to do its job, that's right, so use with caution.