Shell script to check for latest ESR version of Mattermost Server Team Edition, including patch releases.

mattermost-esr-version-check.sh

#!/bin/sh

mm_hook=https://you-mm-server.example/hooks/abcdefghijklmnopqrstuvwxyz
mm_channel=@your_username

read -r latest checksum <<-EOSH
	$(curl --no-progress-meter https://docs.mattermost.com/about/version-archive.html | \
		tr '\r\n' ' ' | \
		perl -ne 'print "$1\t$2\n" if m/<dt\b[^<]+?\bTeam\b[^<]+<[^<]+?\bESR\b(?:(?!<dt\b).)+?>\K(https:\/\/releases.mattermost.com\/[^\s<]+).*?\b([[:xdigit:]]{64})\b/'
	)
	EOSH
if ! [ "$latest" ]; then
	echo Could not determine latest version >&2
	exit 1
fi
version_current=$(sudo -u mattermost /opt/mattermost/bin/mattermost version | grep -Pio '^version:\s*\K\S+')
version_latest=$(printf '%s\n' "$latest" | grep -Po '/\K\d+\.\d+\.\d+(?=/)')

if [ "$version_current" != "$version_latest" ]; then
	curl -sS --json @- "$mm_hook" <<-EOJSON > /dev/null
		{
			"channel": "$mm_channel",
			"text": ":information_source: Mattermost upgrade available: [v$version_latest]($latest)\\nChecksum: \`$checksum\`\\n"
		}
		EOJSON
fi