system

1# {{ ansible_managed }}
2[Unit]
3Description=Check WiFi connectivity and reconnect if the LAN is unreachable
4After=network-online.target
5Wants=network-online.target
6
7[Service]
8Type=oneshot
9
10# **Test the LAN, not the internet.**
11#
12# This unit originally pinged {{ system_wifi_wan_target }} alone, which is the
13# wrong question twice over. The devices this runs on talk to a broker, a
14# registry and the runner -- all on 192.168.34.0/24. They do not need the
15# internet at all.
16#
17#   - A WAN outage with a healthy LAN bounced a working link, taking the
18#     table down for a reason that had nothing to do with it.
19#   - A LAN-side failure while the WAN still answered went undetected, which
20#     is the case this unit exists for.
21#
22# So the LAN check alone decides whether to reconnect. The WAN is probed only
23# to label the log line, because "LAN down, WAN up" and "both down" point at
24# different faults and the distinction is free to record.
25ExecStart=/bin/bash -c '\
26  lan_target="{{ system_wifi_lan_target | default("", true) }}"; \
27  if [ -z "$lan_target" ]; then \
28    lan_target=$(/sbin/ip route show default 0.0.0.0/0 dev {{ system_wifi_interface }} \
29                 | /usr/bin/awk "/default/ {print \\$3; exit}"); \
30  fi; \
31  if [ -z "$lan_target" ]; then \
32    /usr/bin/logger -t wifi-reconnect "no default gateway on {{ system_wifi_interface }}; reconnecting"; \
33    /usr/bin/nmcli device disconnect {{ system_wifi_interface }}; \
34    /bin/sleep 2; \
35    /usr/bin/nmcli device connect {{ system_wifi_interface }}; \
36    exit 0; \
37  fi; \
38  if /bin/ping -c{{ system_wifi_check_count }} -W{{ system_wifi_check_timeout }} "$lan_target" >/dev/null 2>&1; then \
39    exit 0; \
40  fi; \
41  if /bin/ping -c{{ system_wifi_check_count }} -W{{ system_wifi_check_timeout }} {{ system_wifi_wan_target }} >/dev/null 2>&1; then \
42    wan="up"; \
43  else \
44    wan="down"; \
45  fi; \
46  /usr/bin/logger -t wifi-reconnect "LAN gateway $lan_target unreachable (WAN {{ system_wifi_wan_target }} $wan); reconnecting {{ system_wifi_interface }} via NetworkManager"; \
47  /usr/bin/nmcli device disconnect {{ system_wifi_interface }}; \
48  /bin/sleep 2; \
49  /usr/bin/nmcli device connect {{ system_wifi_interface }}; \
50  /usr/bin/logger -t wifi-reconnect "reconnect issued for {{ system_wifi_interface }}"'
51