It's related bug #1834213 and the commit[1], but a follow-up one for upgrade.
[1] https://review.opendev.org/gitweb?p=openstack%2Fcharm-neutron-openvswitch.git;a=commitdiff;h=b76a59299794700fae1878af513c90ca5182a9f6
How to reproduce:
1. install neutron-openvswith charm with bionic GA kernel (4.15) and firewall-driver=openvswitch
2. after installation completed, install hwe or hwe-edge kernel which do not have nf_conntrack_ipv4 or ipv6 modules
3. reboot
The theory here is that the charm will load and write nf_conntrack_ipv4 and ipv6 module into /etc/modules when those modules are available at the time of install (GA kernel in this case). We might be missing some considerations on the upgrade path of kernel, but forcing those two modules loaded even after a kernel upgrade while nf_conntrack module should be sufficient as the patch states.
$ cat /etc/modules
# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
nf_conntrack_ipv4
nf_conntrack_ipv6
$ sudo systemctl status
● myhost
State: degraded
Jobs: 0 queued
Failed: 1 units
Since: Fri 2019-11-08 07:27:08 UTC; 7min ago
$ sudo systemctl --failed modules- load.service loaded failed failed Load Kernel Modules
UNIT LOAD ACTIVE SUB DESCRIPTION
● systemd-
$ sudo systemctl status systemd- modules- load.service modules- load.service - Load Kernel Modules system/ systemd- modules- load.service; static; vendor preset: enabled) modules- load.service( 8)
man: modules- load.d( 5) /lib/systemd/ systemd- modules- load (code=exited, status=1/FAILURE)
● systemd-
Loaded: loaded (/lib/systemd/
Active: failed (Result: exit-code) since Fri 2019-11-08 07:27:08 UTC; 8min ago
Docs: man:systemd-
Process: 543 ExecStart=
Main PID: 543 (code=exited, status=1/FAILURE)
Nov 08 07:27:08 polite-weasel systemd- modules- load[543] : Failed to find module 'nf_conntrack_ipv4' modules- load[543] : Failed to find module 'nf_conntrack_ipv6' modules- load[543] : Inserted module 'iscsi_tcp' modules- load[543] : Inserted module 'ib_iser' modules- load.service: Main process exited, code=exited, status=1/FAILURE modules- load.service: Failed with result 'exit-code'.
Nov 08 07:27:08 polite-weasel systemd-
Nov 08 07:27:08 polite-weasel systemd-
Nov 08 07:27:08 polite-weasel systemd-
Nov 08 07:27:08 polite-weasel systemd[1]: systemd-
Nov 08 07:27:08 polite-weasel systemd[1]: systemd-
Nov 08 07:27:08 polite-weasel systemd[1]: Failed to start Load Kernel Modules.
Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.