bundles/wireguard: add wg_health_check

bundles/wireguard/files/wg_health_check

@@ -0,0 +1,38 @@
+#!/bin/bash
+
+now="$(date +%s)"
+
+everything_up=1
+
+% for peer, ip in sorted(peers.items()):
+# ${peer}
+if ! /usr/bin/ping -c 4 ${ip}
+then
+    everything_up=0
+fi
+
+% endfor
+if [[ "$everything_up" -eq 1 ]]
+then
+    echo "Everything is up as expected"
+    echo "$now" > /var/tmp/wg_all_reached
+    exit 0
+fi
+
+five_min_ago="$(expr $now - 300)"
+last_reached="$(cat /var/tmp/wg_all_reached)"
+
+if [[ "$last_reached" -lt "$five_min_ago" ]]
+then
+    echo "RESTART"
+
+    systemctl restart systemd-networkd
+
+    # only restart once an hour
+    echo "$(expr $now + 3300)" > /var/tmp/wg_all_reached
+elif [[ "$last_reached" -gt "$now" ]]
+then
+    echo "Something's broken, but we have recently restarted"
+else
+    echo "Something's broken, but still in grace time"
+fi