Add MTU migration Phase 1 script

scripts/network/mtu_phase1.sh

@@ -0,0 +1,30 @@
+#!/bin/bash
+# MTU Migration Phase 1 — daemon.json + docker restart
+# Args: $1=hostname $2=sync_epoch
+HOST=$1
+SYNC=$2
+LOG=/volume1/docker/mtu_migration/${HOST}_phase1.log
+exec >> "$LOG" 2>&1
+echo "[$(date)] $HOST waiting for sync epoch $SYNC"
+while [ "$(date +%s)" -lt "$SYNC" ]; do sleep 1; done
+echo "[$(date)] $HOST SYNC reached"
+echo "[$(date)] Writing daemon.json"
+cat > /etc/docker/daemon.json << 'DAEMON'
+{
+  "data-root": "/volume1/docker-root/",
+  "storage-driver": "overlay2",
+  "dns-search": ["."],
+  "mtu": 8950
+}
+DAEMON
+echo "[$(date)] daemon.json: $(cat /etc/docker/daemon.json)"
+echo "[$(date)] Restarting docker..."
+systemctl restart docker
+sleep 15
+echo "[$(date)] eth0 MTU: $(ip link show eth0 | grep -o 'mtu [0-9]*')"
+echo "[$(date)] docker MTU: $(python3 -c "import json; print(json.load(open('/etc/docker/daemon.json')).get('mtu','NOT SET'))")"
+sleep 20
+echo "[$(date)] Docker status: $(systemctl is-active docker)"
+docker node ls 2>&1 || echo "[$(date)] swarm not ready yet"
+echo "[$(date)] $HOST phase1 COMPLETE"
+touch /volume1/docker/mtu_migration/${HOST}_phase1.done