[systemd-devel] [Netatalk-admins] Restart=always and "ExecStartPre" (netatalk)

Thu Sep 29 08:30:43 PDT 2011

the problem is that the "--enable-redhat-systemd" creates only
a systemd-service which starts "/usr/libexec/netatalk/netatalk.sh"
as "type=oneshot" with "RemainAfterExit"

this is all but not a systemd-service because even if you kill
all processes "systemctl status" says "running" in green

> Is a method of using shell-script unsuitable?

yes - there should be a service for every daemon instead a workaround
with a shell-script fire up the single-daemons out of control

they can be ordered with After/Before

from the "netatalk.sh"
>> ATALKD_RUN=no
>> PAPD_RUN=no
>> TIMELORD_RUN=no
>> A2BOOT_RUN=no
>> ATALK_ZONE=
>> ATALK_BGROUND=no

this would not be needed if we have 6 systemd-services which can
all be enabled/disabled/stoped/started and would do this in a
right order if needed - only my wish would be that "systemctl stop/start afpd.service"
would start/stop the cnid-daemon which should also be a own service

the benefit is that this all would be run smoother and every single-service
could use "Restart=always/onfailure" and the processes would be really
crontrolled by systemd

> This method is inapplicable to netatalk 2.2.2.
> Netatalk have afpd, cnid_metad, atalkd, papd, timelord and a2boot daemons

i know that my systemd-service is unacceptable upstream
but here it is enough this time because only afpd is used

> Systemd MUST control all daemons.

but it does not!
systemd controls exactly nothing with the "/usr/libexec/netatalk/netatalk.sh"
and that is my problem with the current implementation of "nteatalk.service"

Am 29.09.2011 17:15, schrieb HAT:
> Hi, I'm a member of netatalk-admins ML.
> I'm subscribing to systemd-devel ML temporarily.
> and I'm going to unsubscribe when this problem is solved.
> 
> I added an "--enable-redhat-systemd" option to netatalk 2.2.1.
> This implementation is a copy of netatalk.service and netatalk.sh in
> netatalk-2.2.0-4.fc17.src.rpm because I don't have the knowledge of systemd.
> <http://koji.fedoraproject.org/koji/buildinfo?buildID=259507>
> This message is sent also to rpm packager.
> 
> If someone offers more suitable patch, I will apply it to netatalk 2.2.2.
> 
>> [root at testserver:~]$ cat /lib/systemd/system/netatalk.service
>> [Unit]
>> Description=Apple-File-Server
>> After=syslog.target network.target avahi-daemon.service
>> [Service]
>> Type=forking
>> PIDFile=/var/run/netatalk.pid
>> ExecStartPre=/usr/sbin/cnid_metad -l log_note
>> ExecStart=/usr/sbin/afpd -P /var/run/netatalk.pid -F /etc/netatalk/afpd.conf
>> Restart=always
>> RestartSec=1
>> [Install]
>> WantedBy=multi-user.target
> 
> This method is inapplicable to netatalk 2.2.2.
> Netatalk have afpd, cnid_metad, atalkd, papd, timelord and a2boot daemons.
> Systemd MUST control all daemons.
> 
> For the moment, "/etc/netatalk/netatalk.conf" must be read because
> the following parameters cannot be set in "/etc/netatalk/afpd.conf".
> 
>    ATALK_UNIX_CHARSET=
>    ATALK_MAC_CHARSET=
>    AFPD_MAX_CLIENTS=
>    CNID_CONFIG=
> 
> I think these parameters should be abolished in the future (netatalk 3.0?).
> But it is impossible in current netatalk 2.2.x.
> 
> In case of netatalk 2.2.1,
> a shell-script "/usr/libexec/netatalk/netatalk.sh" calls netatalk.conf.
> Is there any method of otherwise reading netatalk.conf?
> 
> IMHO, a better method is that passing options to netatalk.sh.
> 
>    ExecStart=/bin/sh -c "exec /usr/libexec/netatalk/netatalk.sh start"
>    ExecStop=/bin/sh -c "exec /usr/libexec/netatalk/netatalk.sh stop"
>    ExecRestart=/bin/sh -c "exec /usr/libexec/netatalk/netatalk.sh restart"
> 
> Is a method of using shell-script unsuitable?
> 
> 
>> thank you for your reply
>>
>> first i tried two services (netatalk.service + netatalk-cnid.service)
>> but for whatever reason /usr/sbin/cnid_metad will be started with
>> a correct zero-return-value but the process is closed, tried preforking/simple
>>
>> the other "problem" is that i want take away complexity for start/restart
>> at the user/admin-level there should be only used "netatalk.service"
>> this works fine with Requires= for the first start, but not when stop
>> netatalk.service in a way that netatalk-cnid.service is stopped also
>>
>> background-informations:
>> afpd: the apple fileserver
>> cnid_meta: a shared service for the AppleDB
>>
>> upstream has included a systemd option in netatalk-2.2.1-p1 but
>> the created systemd-service does not satisfy me because it is a
>> shellscript reading/defining some shell-vars and starting both
>> processes as "oneshot" with "RemainAfter" wthat means that
>> "Restart" is generally not possible and even if you kill both
>> processes "systemctl status" says "running", so this is a wrapper
>> which is faking a systend-service without any benefit
>>
>> a copy of my reply goes ot the netatalk-mailing-list
>> maybe they could optimize this upstream and provide the
>> service file as textfiel in the tarball instead generate
>> it with the configure-options to make custom builds easier
>>
>> however, the fileserver is an internal service but i would love to use the
>> restart-options and install a cron-script parsing /var/log/messages for
>> systemd-restart-events to send mail-notifies
>>
>> Retart=always is one of the few current available improvements of systemd
>> over the old sysvinit to make even rock solid services more stable by
>> restart them at the few crashes instead fireup a alarm-mail
>>
>> thanks!
>>
>>
>> Am 28.09.2011 22:48, schrieb Michal Schmidt:
>>> On Wed, 28 Sep 2011 17:49:54 +0200 Reindl Harald wrote:
>>>> why does systemd not restart a killed service if the
>>>> "ExecStartPre"-process is still running, see below - at my opinion
>>>> after "killall afpd" the service should be restarted and in a perfect
>>>> case even if "ExecStartPre"-process dies
>>>>
>>>> systemd-26-10.fc15.x86_64
>>>
>>> I see at least three issues here. See below.
>>>
>>>> [root at testserver:~]$ cat /lib/systemd/system/netatalk.service
>>>> [Unit]
>>>> Description=Apple-File-Server
>>>> After=syslog.target network.target avahi-daemon.service
>>>> [Service]
>>>> Type=forking
>>>> PIDFile=/var/run/netatalk.pid
>>>> ExecStartPre=/usr/sbin/cnid_metad -l log_note
>>>
>>> issue #1:
>>> ExecStartPre is not supposed to fork off daemons. A future version of
>>> systemd might even enforce this rule. The service should be split into
>>> two.
>>>
>>>> ...
>>>> [root at testserver:~]$ systemctl status netatalk.service
>>>> netatalk.service - Apple-File-Server
>>>>           Loaded: loaded (/lib/systemd/system/netatalk.service)
>>>>           Active: active (running) since Wed, 28 Sep 2011 17:45:55
>>>> ...
>>>> Main PID: 1812 (code=exited, status=0/SUCCESS)
>>>
>>> issue #2:
>>> This Main PID looks like stale information from a previous run of the
>>> service. This is a minor bug in systemd that it does not reset it.
>>>
>>> There are two reasons why systemd failed to detect the new main PID:
>>>  - issue #3: afpd has a racy daemonization sequence. It writes its PID
>>>    file too late. My recently proposed patch "service: delayed main PID
>>>    guessing" should be able to workaround it.
>>>  - Given that systemd could not read the information from the PID file,
>>>    it tried to guess the main PID, but it also failed, because there
>>>    are two top-level processes in the cgroup:
>>>
>>>> CGroup: name=systemd:/system/netatalk.service
>>>> ├ 1999 /usr/sbin/cnid_metad -l log_note
>>>> └ 2002 /usr/sbin/afpd -P /var/run/netatalk.pid -F /etc/netatalk/afpd.conf
>>>
>>> systemd could tell which one of them is the main PID.
>>>
>>> When the main PID is not known, the only way to detect the death of the
>>> service is to watch for the cgroup getting empty.
>>>
>>> Michal

-- 

Reindl Harald
the lounge interactive design GmbH
A-1060 Vienna, Hofmühlgasse 17
CTO / software-development / cms-solutions
p: +43 (1) 595 3999 33, m: +43 (676) 40 221 40
icq: 154546673, http://www.thelounge.net/

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