Shell script to check for latest version of Mattermost Server, including patch releases, optionally filtered to Team Edition and/or ESR.

mattermost-version-check

#!/bin/sh
set -e

version_current=$(
	sudo -u "${MM_USER:-mattermost}" "${MM_BIN:-/opt/mattermost/bin/mattermost}" version | \
		grep -Pio '^version:\s*\K\S+'
)

if [ "${MM_TEAM_ED:-0}" -gt 0 ]; then
	ed=Team
else
	ed=Enterprise
fi
if [ "${MM_ESR:-0}" -gt 0 ]; then
	esr=1
else
	esr=0
fi

index=https://raw.githubusercontent.com/mattermost/docs/refs/heads/master/source/product-overview/version-archive.rst
index=$(curl --no-progress-meter "$index")
[ "$index" ]
latest=$(
	awk -v ed=$ed -v esr=$esr "$(cat <<-'EOAWK'
		BEGIN {
			preamble = 1
			RS = "\n +Mattermost " ed " Edition v"
			FS = "\n +-"
		}
		preamble {
			preamble=0
			next
		}
		{
			if (esr && !match($1, /\(ESR\)/))
				next
			v = gensub(/[[:space:]].*/, "", 1, $1)
			if (!match($3, "SHA-256")) {
				print "no checksum found"
				exit 1
			}
			u = gensub(/^[^`]*`+|`.*/, "", "g", $2)
			c = gensub(/^[^`]*`+|`.*/, "", "g", $3)
			printf "%s\t%s\t%s\n", v, u, c
			exit
		}
		EOAWK
	)" <<-EORST
		$index
		EORST
)
read -r version_latest archive checksum <<-EOT
	$latest
	EOT

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

Call with env vars like so:

MM_HOOK=https://your-mm-server.example/hooks/abcdefghijklmnopqrstuvwxyz \
	MM_CHANNEL=@your_username \
	MM_TEAM_ED=1 \
	MM_ESR=1 \
	mattermost-version-check

But probably best to put them in a "config" file then source it:

(set -a && . ./.mm-vc-env && mattermost-version-check)

You can override the system user account and path to binary with MM_USER and MM_BIN, if you did not use the defaults.