Check for Linux host (Debian) available updates and post to slack

check-for-updates.sh

#!/usr/bin/env bash

set -o errexit
set -o nounset
set -o pipefail
if [[ "${TRACE-0}" == "1" ]]; then
    set -o xtrace
fi

# Check for upgradable packages
check=$(apt-get upgrade --simulate 2>/dev/null )

if [[ $check == *"0 upgraded"* ]]
then
        echo "Nothing to do for today."
        exit
fi

send_slack_notification() {
        slack_webhook_url="YOUR_SLACK_WEBHOOK"
        LIST=$(apt list --upgradable) 2>/dev/null

        message="$(hostname) Updates are available.
        \n
        $LIST
        \n
        Run 'sudo apt-get upgrade' to apply them."

        curl -X POST -H 'Content-type: application/json' --data "{\"text\":\"$message\"}" "$slack_webhook_url"
}

send_slack_notification