first pass

scripts/check-image-updates.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+# =============================================================
+#  check-image-updates.sh
+#  Checks all running containers for newer images and caches
+#  results to /tmp/.docker-updates for the MOTD to display.
+#
+#  Usage:
+#    bash scripts/check-image-updates.sh
+#
+#  Add to cron for automatic checks (e.g. daily at 3am):
+#    0 3 * * * bash /opt/stacks/matrix/scripts/check-image-updates.sh
+# =============================================================
+
+set -euo pipefail
+
+CACHE="/tmp/.docker-updates"
+TMP=$(mktemp)
+
+echo "# generated $(date -u +"%Y-%m-%dT%H:%M:%SZ")" > "$TMP"
+
+while IFS='|' read -r name image; do
+  OUTPUT=$(docker pull "$image" 2>&1 || true)
+  if echo "$OUTPUT" | grep -q "Downloaded newer image"; then
+    echo "$name  →  $image" >> "$TMP"
+  fi
+done < <(docker ps --format '{{.Names}}|{{.Image}}' | sort)
+
+mv "$TMP" "$CACHE"
+
+UPDATES=$(grep -v '^#' "$CACHE" | grep -c . || true)
+if [ "$UPDATES" -gt 0 ]; then
+  echo "✅  $UPDATES image(s) updated — cache written to $CACHE"
+else
+  echo "✅  All images current — cache written to $CACHE"
+fi