Comment 0 for bug 1884248

I just reinstalled my RPI3 router from Eoan to Focal but a lot of things about networkd broke. I'm not sure whether they are related or not.

The first thing I noticed was, that I did not get my upstream DNS servers. I use a dispatcher script to extract the information from the json environment variable when my uplink becomes routable. Using a test script to dump the environment I found this:

IP6_ADDRS=
PWD=/
json={"A": ["ress: 119.224.106.22 (DHCP4)"], "AdministrativeState": "configuring", "Auto negot": ["tion: yes", "peed: 100Mbps", "plex: full", "Port: mii"], "G": ["eway: 119.224.106.21", "DNS: 202.180.64.10", "202.180.64.11", ""], "HW A": ["ress: b8:27:eb:b6:a5:f4 (Raspberry Pi Foundation)", "MTU: 1500 (max: 65535)"], "InterfaceName": "wan", "Jun 20 00:01:49": ["mnus systemd-networkd[534]: wan: netdev ready", "mnus systemd-networkd[534]: wan: Link UP", "mnus systemd-networkd[534]: wan: Gained carrier"], "Jun 20 00:01:50": ["mnus systemd-networkd[534]: wan: Lost carrier"], "Jun 20 00:01:51": ["mnus systemd-networkd[534]: wan: Gained carrier"], "Jun 20 00:01:53": ["mnus systemd-networkd[534]: wan: DHCPv4 address 119.224.106.22/30 via 119.224.106.21"], "Lin": ["File: /usr/lib/systemd/network/99-default.link"], "Networ": ["File: /etc/systemd/network/07-wan.network", "Type: vlan", "tate: routable (configured)", "iver: 802.1Q VLAN Support"], "OperationalState": "routable", "Queue Length (": ["/Rx): 1/1"], "State": "routable (configuring)", "Type": "vlan"}
AdministrativeState=configuring
IFACE=wan
LANG=en_NZ.UTF-8
INVOCATION_ID=384cc7de4e8d45e48ecb2ecf3cb55508
IP_ADDRS=
ESSID=
ADDR=
NOTIFY_SOCKET=/run/systemd/notify
SHLVL=1
STATE=routable
JOURNAL_STREAM=9:35403
OperationalState=routable
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
networkd_dispatcher_args=--run-startup-triggers

Note that the script worked perfectly fine on Eoan.

Also when I tried to get the dump above, I ran the following command after installing the test-script:
ip link delete wan type vlan; systemctl restart systemd-networkd
in order to force networkd to recreate and reconfigure my uplink interface. Doing this resulted in all connectivity with the router being lost (up- and downstream). After a restart, I found the following in the networkd journal indicating that networkd had in fact crashed.

Jun 19 23:59:58 tumnus systemd-networkd[539]: wan: Link DOWN
Jun 19 23:59:58 tumnus systemd-networkd[539]: wan: Lost carrier
Jun 19 23:59:58 tumnus systemd-networkd[539]: wan: DHCP lease lost
Jun 19 23:59:58 tumnus systemd[1]: Stopping Network Service...
Jun 19 23:59:58 tumnus systemd[1]: systemd-networkd.service: Succeeded.
Jun 19 23:59:58 tumnus systemd[1]: Stopped Network Service.
Jun 19 23:59:58 tumnus systemd[1]: Starting Network Service...
Jun 19 23:59:59 tumnus systemd-networkd[1986]: private: netdev ready
Jun 19 23:59:59 tumnus systemd-networkd[1986]: Enumeration completed
Jun 19 23:59:59 tumnus systemd[1]: Started Network Service.
Jun 19 23:59:59 tumnus systemd-networkd[1986]: private: netdev exists, using existing without changing its parameters
Jun 20 00:00:00 tumnus systemd[1]: systemd-networkd.service: Main process exited, code=dumped, status=11/SEGV
Jun 20 00:00:00 tumnus systemd[1]: systemd-networkd.service: Failed with result 'core-dump'.
Jun 20 00:00:00 tumnus systemd[1]: systemd-networkd.service: Scheduled restart job, restart counter is at 1.
Jun 20 00:00:00 tumnus systemd[1]: Stopped Network Service.
Jun 20 00:00:00 tumnus systemd[1]: Starting Network Service...
Jun 20 00:00:01 tumnus systemd-networkd[2034]: private: netdev ready
Jun 20 00:00:01 tumnus systemd-networkd[2034]: Enumeration completed
Jun 20 00:00:01 tumnus systemd[1]: Started Network Service.
Jun 20 00:00:01 tumnus systemd-networkd[2034]: private: netdev exists, using existing without changing its parameters
Jun 20 00:00:01 tumnus systemd-networkd[2034]: wan: Link UP
Jun 20 00:00:01 tumnus systemd-networkd[2034]: wan: Gained carrier
Jun 20 00:00:01 tumnus systemd-networkd[2034]: private: Could not join netdev: Can not enslave a bridge to a bridge. Too many levels of symbolic links
Jun 20 00:00:01 tumnus systemd-networkd[2034]: private: Failed
Jun 20 00:00:01 tumnus systemd-networkd[2034]: wan: DHCPv4 address 119.224.106.22/30 via 119.224.106.21
Jun 20 00:01:22 tumnus systemd[1]: Stopping Network Service...
Jun 20 00:01:22 tumnus systemd-networkd[2034]: wan: DHCP lease lost
Jun 20 00:01:22 tumnus systemd[1]: systemd-networkd.service: Succeeded.
Jun 20 00:01:22 tumnus systemd[1]: Stopped Network Service.
-- Reboot --

However, no crash file had been generated.
The system is running systemd 245.4-4ubuntu3.1 and networkd-dispatcher 2.0.1-1.