On Sat, Jul 12, 2014 at 10:00 AM, Sam Varshavchik <mrsam@xxxxxxxxxxxxxxx> wrote: > > Now that I have your attention, the background is as follows. This is a > server with only statically configured network interfaces. NetworkManager is > not installed. All network interfaces are statically configured via > /etc/sysconfig/network-scripts. > > The server is regularly updated to current Fedora packages. For the last > month, or so, the server has failed to come up in a sane state, reliably. > After it responds to pings, after ssh-ing in, and examining the aftermath, > the logs of all network services are consistent, in that they claim that > each network service – which includes: named-chroot, httpd, dhcpd, and > privoxy – their boot logs claim that no network interfaces were up at the > time they're started. > > After finally getting pissed about having to manually re-brain the server, > each time it boots, I attached a console monitor, and observed that the boot > goes /very/ quickly, and the console login prompt comes up about 20-30 > seconds before the server even starts responding to pings. Looks like the > multi-user target is reached way long before networking even comes up. > > Last week, I've commented on the following curiosity: after sifting through > systemd's documentation, their documentation claims that "network.target" > gets reached only after basic networking is up, and "network-online.target" > gets reached only after all network interfaces are initialized. > > Problem number one is that all servers specify "After=network.target", when, > according to how I interpret this, they should all really specify > "After=network-online.target". > > After that, it came to my attention that there's a NetworkManager optional > subpackage that installs a service that waits for network interfaces to come > up, and it's specified as "Before=network.target network-online.target". It > seems fairly obvious to me that it should really be > "Before=network-online.target" and "After=network.target", with all other > services that require a functioning network specifying > "After=network-online.target". That made logical sense to me, but it seems > that this confusing arrangement makes logical sense to someone else, so, > whatever. I do not have NetworkManager installed, but, I figure, why not > take a crack at whipping up a dirty hack that basically does the same thing? > > But the unexpected result from the hack is that it seems to provide solid > proof that systemd's dependency resolution is not working, but before I > Bugzilla this (as little hope one might have from getting anything useful > done by Bugzillaing this), I'd like to hear some consensus that I am > interpreting the following data right. Who knows, I might actually have made > a mistake, somewhere. > > Let's take a look at what named-chroot.service says: > > [Unit] > Description=Berkeley Internet Name Domain (DNS) > Wants=nss-lookup.target > Before=nss-lookup.target > After=network.target > > Are we all in agreement that named-chroot.service should only be started > after network.target gets reached? Ok. > > Now, here's my hack, which is basically a clone of that NetworkManager > subpackage: > > # cat /etc/systemd/system/wait-for-network.service > [Unit] > Description=Wait for network ports to be initialized > Before=network.target network-online.target > > [Service] > Type=oneshot > ExecStart=/root/bin/wait-for-network > > [Install] > WantedBy=multi-user.target > > Are we all in agreement that: > > 1) This is a one-shot service, and according to systemd's documentation, > systemd must wait until this script is complete, before it's considered > started. > > 2) Until it's complete, network.target isn't reached. > > 3) Therefore, this script must finish before systemd should start > named-chroot.service > > Yet, after testing this script, then activating it, the server still came up > utterly brainless after the reboot. The results: > > systemctl status named-chroot.service reports: > > named-chroot.service - Berkeley Internet Name Domain (DNS) > Loaded: loaded (/usr/lib/systemd/system/named-chroot.service; enabled) > Active: active (running) since Sat 2014-07-12 09:24:29 EDT; 3min 28s ago > … > > So, systemd started named-chroot.service at 09:24:29. > > My script logs the current timestamp. The output from > /root/bin/wait-for-network was as follows: > > Sat Jul 12 09:24:27 2014 > Interface: lo is up > Sat Jul 12 09:24:32 2014 > Interface: lan0 is up > Interface: lo is up > Interface: wan0 is down > Sat Jul 12 09:24:37 2014 > Interface: lan0 is up > Interface: lo is up > Interface: wan0 is up > > systemd started this script at 09:24:27. This script spun its wheels until > 09:24:37, at which time all network interfaces finally came up. I'm happy to > post the contents of this short script; however I don't think that it's > relevant here, because the problem is that this script was running when > systemd decided to run named-chroot.service, even though, according to the > above, this should not happen. > > So, either I'm misreading the description of "oneshot" in > systemd.service(5); and "Before" and "After" in systemd.unit(5), or systemd > is broken completely. I think that my understanding of systemd's > documentation is very reasonable. So, either systemd is broken, or, if it's > supposedly working how it should be working, its documentation is crap, and > is impossible to follow. I see no other possibilities. "NetworkManager-wait-online.service" has: <begin> After=NetworkManager.service Wants=network.target Before=network.target network-online.target </end> Perhaps you should replicate that in "wait-for-network.service" for it to behave as you intend it. I assume that you can replicate "After=NetworkManager.service" with "After=network.service" even though your network's being brought up by "/etc/rc.d/init.d/network". What do you have in "/root/bin/wait-for-network"? -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
