Script to notify on Slack when updates are available in APT. Logs already reported packages on a $0.log file.

apt-slack.sh

#!/bin/bash
#
# Author: Alexander Karlstad <carestad@github>
# Updated: 2019-07-17

# Configurable variables
slack_channel="@alexander"
slack_icon=":information_source:"
slack_user="apt@$(hostname -f)"
slack_webhook=""

# Internal variables
pkglog="$0.log"
notify=()
upgradeable="$(apt-get upgrade -s | grep ^Inst | awk '{ print $2,$3; }' | tr -d '[]')"

# No pkglog file? Create it
if [ ! -f "$pkglog" ]; then
  touch "$pkglog"
fi

# If nothing to upgrade, we have done it already. Make sure pkglog file is empty
if [ -z "$upgradeable" ]; then
  echo "No packages to update"
  echo "" > "$pkglog"

  exit 0
fi

while read line; do
  if ! grep "$line" "$pkglog"; then
    notify+=("$line")
  fi
done <<< "$upgradeable"

# Packages can be updated, but have been reported already
if [[ -z "${notify[*]}" ]]; then
  echo "Package to upgrade available, but already reported"
  exit 0
fi

markdown=""
for line in "${notify[@]}"; do
  pkg="$(echo "$line" | cut -d" " -f1)"
  ver="$(echo "$line" | cut -d" " -f2)"
  markdown="$markdown\n• *${pkg}* (_${ver}_)"
done

curl -s -X POST -H 'Content-type: application/json' -d "{'channel': '$slack_channel', 'icon_emoji': '$slack_icon', 'username': '$slack_user', 'text': 'The following packages can be updated:${markdown}', 'type': 'mrkdwn'}" $slack_webhook > /dev/null

# Add to log
for line in "${notify[@]}"; do
  echo "$line" >> "$pkglog"
done