I am having intermittent problems on startup in which network services do not start properly, generally with messages suggesting the network interface they need is not available. If I stop and start them after, they will run. I suspect this is a result of the interaction of systemd, ifupdown, and a pre-up script that takes a while to execute. But if I look at things now it seems the dependencies in place should suffice. Of course, this is after I restarted it, and so perhaps the dependency is added dynamically, too late to do any good.
I think what I need is for network-online.target not to be ready until after the interfaces ifup controls are up, but I'm not sure how to do it. Also not sure it's the problem, particularly since some information indicates it already has such a dependency. Details: My main interface is controlled by /etc/network/interfaces that includes allow-hotplug /enp* iface enp5s0 inet static # etc The interface has a pre-up script that has over 1,000 iptables add lines for blacklists, and I suspect this is slowing things down enough to cause trouble. I was not having problems when the script was shorter. This is a problem other have encountered: https://unix.stackexchange.com/questions/209832/debian-systemd-network-online-target-not-working https://unix.stackexchange.com/questions/257888/systemd-wait-for-network-interface-to-be-up-before-running-service Various solutions are suggested, with a leading one being a dependency on network-online.target. But all my network services already have that dependency. For example, # systemctl cat tftpd-hpa # /run/systemd/generator.late/tftpd-hpa.service # Automatically generated by systemd-sysv-generator [Unit] Documentation=man:systemd-sysv-generator(8) SourcePath=/etc/init.d/tftpd-hpa Description=LSB: HPA's tftp server Before=multi-user.target Before=multi-user.target Before=multi-user.target Before=graphical.target After=remote-fs.target After=network-online.target Wants=network-online.target tftpd-hpa is the service that fails most consistently. # systemctl list-dependencies tftpd-hpa Mon 13 Jul 2020 02:42:22 PM PDT tftpd-hpa.service ● ├─system.slice ● ├─network-online.target ● │ ├─networking.service ● │ └─NetworkManager-wait-online.service ● └─sysinit.target etc. Notably absent from network-online.target's dependencies is anything related to ifup. However, ifup@enp5s0.service appears as an After dependency of network-online.target when viewed another way: # systemctl show network-online.target Id=network-online.target Names=network-online.target Wants=NetworkManager-wait-online.service networking.service WantedBy=tftpd-hpa.service nmbd.service hddtemp.service docker.service mythtv-backend.service exim4.service hylafax.service smbd.service inetd.service isc-dhcp-server.service Conflicts=shutdown.target Before=hylafax.service isc-dhcp-server.service smbd.service exim4.service apt-daily.service rc-local.service apt-daily-upgrade.service mythtv-backend.service apcupsd.service tftpd-hpa.service docker.service inetd.service hddtemp.service shutdown.target nmbd.service After=ifup@enp5s0.service network.target networking.service NetworkManager-wait-online.service Documentation=man:systemd.special(7) https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget Any suggestions? Ideally I would not be tied to the interface name, so that if I plug the network cable into another port things will still work. Thanks. Ross Boylan
