[systemd-devel] Have timers fire after boot is complete
Hello, one of the most-requested features that is not present in systemd currently is a true rc.local-type functionality that runs after all other services. I haven't read all past discussions, but from what I've gathered the main objection from the systemd developers is that having a catch-all After=* dependency would not be the sane thing to do. That said, the frequency of people requesting this feature indicates that there are valid use cases for this kind of functionality. To give a few examples: - remove /etc/nologin after everything is started (some administrators may want this as a policy, while other's don't) - send an email to the admin btw. computer XYZ just finished rebooting and here are the log entries generated from the boot process - in linux HA you may want to defer the node rejoining the cluster to the point when you know that the server has correctly booted and none of the core services failed in the process I'm sure there are quite a few more. Current solutions are type=idle units (which don't really work for many of the above use cases, since type=idle is essentially type=simple) or setting SysVStartPriority to 99 (as done in Fedora), but that only orders relative to sysv services, not to native services - and in a setup where most if not all services are native, this will not have the desired effect. In order to implement this feature in systemd, I've gone another direction: Instead of having a service for which some ordering constraints are ensured, why not have a timer? There is already OnBootSec=, which is relative to the time when the kernel was activated, so the idea was to have another timer base for this specific purpose. The patch I'm going to send as a reply to this email will implement OnTransactionFinishedSec=. When a timer is started and contains such an entry, it will tell the manager to ping it as soon as the transaction is complete. The manager then proceeds to activate all other units in the transaction and as soon as it reaches manager_check_finished and no jobs are left in the run_queue, and after it closes the idle pipe to trigger the type=idle jobs, it pings the timers again. The timers will then remember the finish time of the current transaction and use that as a base for all OnTransactionFinishedSec= entries. This also has some nice semantics if you want to run something not immediately after boot but e.g. 5 minutes later. If you think, well, boot time is ~30s, I just put in OnBootSec=330s, this will usually give the expected results. However, if for some reason you first boot into rescue.target, then do some stuff for 10 minutes and then run systemctl isolate default.target, the timer will fire immediately while the system is still in the process of booting, which may not be what you want. On the other hand, OnTransactionFinishedSec= will only start counting once you reach the transaction that started the timer, which usually would be the boot transaction (if timer is in default.target) but could also be the isolate transaction in the above scenario. Anyway, I hope I've provided a rationale why this can be a useful feature to have in systemd. The patch will follow in a reply to this mail. Regards, Christian ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Have timers fire after boot is complete
On 09/27/2012 08:33 AM, Christian Seiler wrote: one of the most-requested features that is not present in systemd currently is a true rc.local-type functionality that runs after all other services. Any particular reason why those user just dont create type oneshot unit then order it as they see fit with after and or before? JBG ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Have timers fire after boot is complete
Le jeudi 27 septembre 2012 à 11:07 +, Jóhann B. Guðmundsson a écrit : On 09/27/2012 08:33 AM, Christian Seiler wrote: one of the most-requested features that is not present in systemd currently is a true rc.local-type functionality that runs after all other services. Any particular reason why those user just dont create type oneshot unit then order it as they see fit with after and or before? Mostly because many users have no idea after which units they should schedule their target. And they are used to having a run as last script in their distribution (see https://bugzilla.novell.com/show_bug.cgi?id=778715 which links to openSUSE forum on this topic). -- Frederic Crozat fcro...@suse.com SUSE ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Have timers fire after boot is complete
Am 27.09.2012 13:07, schrieb Jóhann B. Guðmundsson: On 09/27/2012 08:33 AM, Christian Seiler wrote: one of the most-requested features that is not present in systemd currently is a true rc.local-type functionality that runs after all other services. Any particular reason why those user just dont create type oneshot unit then order it as they see fit with after and or before? because systemd is the software who knows the complete ordering of all services and could easily decide what is after independent of which servcies are active now and maybe installed later and has to be added manually after install them? signature.asc Description: OpenPGP digital signature ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Have timers fire after boot is complete
Am 27.09.2012 12:07, schrieb Jóhann B. Guðmundsson: On 09/27/2012 08:33 AM, Christian Seiler wrote: one of the most-requested features that is not present in systemd currently is a true rc.local-type functionality that runs after all other services. Any particular reason why those user just dont create type oneshot unit then order it as they see fit with after and or before? Let's say I have a couple of servers lying around, each with different services installed. Now I want to distribute a single unit file that is always run at the end sending me an email that the system has rebooted and sending me all log messages generated in the boot process so I can see if everything went correctly. Obviously, I can add lots and lots of different units to After= of that service, but as soon as some other service is added to the list, I have to adjust it. Also, the After= dependency isn't really correct here: Such a script doesn't specifically depend on e.g. After=apache.service (it doesn't really care about that) but rather something that should run at a certain time, thus the idea of using a timer for this feature. Christian ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Have timers fire after boot is complete
'Twas brillig, and Christian Seiler at 27/09/12 09:33 did gyre and gimble: Hello, one of the most-requested features that is not present in systemd currently is a true rc.local-type functionality that runs after all other services. I haven't read all past discussions, but from what I've gathered the main objection from the systemd developers is that having a catch-all After=* dependency would not be the sane thing to do. Can you just use a Type=idle unit? From man systemd.service: Behavior of idle is very similar to simple, however actual execution of a the service binary is delayed until all jobs are dispatched. This may be used to avoid interleaving of output of shell services with the status output on the console. This isn't necessarily guaranteed to be last but I think it would generally be the case... unless I've misunderstood it. Col -- Colin Guthrie gmane(at)colin.guthr.ie http://colin.guthr.ie/ Day Job: Tribalogic Limited http://www.tribalogic.net/ Open Source: Mageia Contributor http://www.mageia.org/ PulseAudio Hacker http://www.pulseaudio.org/ Trac Hacker http://trac.edgewall.org/ ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Have timers fire after boot is complete
I haven't read all past discussions, but from what I've gathered the main objection from the systemd developers is that having a catch-all After=* dependency would not be the sane thing to do. Can you just use a Type=idle unit? From man systemd.service: Behavior of idle is very similar to simple, however actual execution of a the service binary is delayed until all jobs are dispatched. This may be used to avoid interleaving of output of shell services with the status output on the console. The problem here is that a Type=idle service is basically a type=simple service and you might want to have Type=forking or Type=oneshot services which you want to start. Also, my patch is more generic - it allows an arbitrary time to pass before actually running the event. My patch basically implements Type=idle for timers. This isn't necessarily guaranteed to be last but I think it would generally be the case... unless I've misunderstood it. Sure, there's no guarantee that it is the last, since all are executed in parallel - just like Type=idle services. Christian ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Have timers fire after boot is complete
If you want to run a script in the very end of everything you simply order it after the default target as in [Unit] Description=My custom script After=default.target [Service] Type=oneshot ExecStart=/path/to/my/custom/script [Install] WantedBy=default.target Hmmm, I remember vaguely that this didn't produce the desired results for some people and that there's a reason why Fedora's rc-local.service only uses the SysVPriority=99 hack and not After=default.target. But perhaps I'm wrong, I'll look into that. Christian ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Have timers fire after boot is complete
On 09/27/2012 11:17 AM, Frederic Crozat wrote: Le jeudi 27 septembre 2012 à 11:07 +, Jóhann B. Guðmundsson a écrit : On 09/27/2012 08:33 AM, Christian Seiler wrote: one of the most-requested features that is not present in systemd currently is a true rc.local-type functionality that runs after all other services. Any particular reason why those user just dont create type oneshot unit then order it as they see fit with after and or before? Mostly because many users have no idea after which units they should schedule their target. And they are used to having a run as last script in their distribution Ordering it after the default target should suffice. In Fedora we still support rc.local we just dont ship it by default so if you want/prefer the old behavior. you only need to create it and set it up correctly as in # echo '#!/bin/sh' /etc/rc.d/rc.local chmod 755 /etc/rc.d/rc.local and systemd will pick it but it wont give you the same flexibility as native systemd units can do. (see https://bugzilla.novell.com/show_bug.cgi?id=778715 which links to openSUSE forum on this topic). Out of the four forum samples in comment 2 on this bug, 3 of the forum post ( from the look of it ) are workarounds for genuine bugs and one should belong in a rule-*/route-* files under /etc/sysconfig/network which would be picked up by networking scripts ( given that suse networking scripts support that ) . JBG ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Have timers fire after boot is complete
Le jeudi 27 septembre 2012 à 12:55 +, Jóhann B. Guðmundsson a écrit : On 09/27/2012 11:17 AM, Frederic Crozat wrote: Le jeudi 27 septembre 2012 à 11:07 +, Jóhann B. Guðmundsson a écrit : On 09/27/2012 08:33 AM, Christian Seiler wrote: one of the most-requested features that is not present in systemd currently is a true rc.local-type functionality that runs after all other services. Any particular reason why those user just dont create type oneshot unit then order it as they see fit with after and or before? Mostly because many users have no idea after which units they should schedule their target. And they are used to having a run as last script in their distribution Ordering it after the default target should suffice. I tested that a loong time ago and it wasn't working as expected (but I should re-test that). In Fedora we still support rc.local we just dont ship it by default so if you want/prefer the old behavior. We also have boot.local (which is equivalent to rc.local) and correctly handled by systemd. (see https://bugzilla.novell.com/show_bug.cgi?id=778715 which links to openSUSE forum on this topic). Out of the four forum samples in comment 2 on this bug, 3 of the forum post ( from the look of it ) are workarounds for genuine bugs and one should belong in a rule-*/route-* files under /etc/sysconfig/network which would be picked up by networking scripts ( given that suse networking scripts support that ) . I didn't had time to reply to this bug, yet. I think we (systemd community) need to improve documentation for people who need to write workarounds (or whatever we call them) and were used to after.local (or whatever it is called in various distributions). -- Frederic Crozat fcro...@suse.com SUSE ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Have timers fire after boot is complete
On Thu, Sep 27, 2012 at 01:43:34PM +0100, Christian Seiler wrote: The problem here is that a Type=idle service is basically a type=simple service and you might want to have Type=forking or Type=oneshot services which you want to start. Maybe sometimes like: [Service] Type=idle RemainAfterExit=yes ExecStart=/usr/bin/systemctl start iamlate.target And create this simple iamlate.target and have your after everything services and scripts have WantedBy=iamlate.target? -- Tomasz Torcz Never underestimate the bandwidth of a station xmpp: zdzich...@chrome.plwagon filled with backup tapes. -- Jim Gray ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
