[systemd-devel] Query regarding NOTIFY_SOCKET

[Alessandro Puccetti]

On Tue, Nov 8, 2016 at 2:28 PM, Raghavendra. H. R <raghuhr84 at gmail.com>
wrote:

> Hi Tomasz,
>
> Thanks for pointing out the mistake. I actually missed the line
> "Type=notify" in the mail.
> I found the journalctl logs and from that I can make out the real problem
> is not about NOTIFY_SOCKET. It is about child process in my application
> *Myapp.*
>
> Below given is my Service file.
>
> *[Unit]*
> *Description=Sd_notify example*
>
> *[Service]*
> *Type=notify*
> *ExecStart=/etc/Myapp*
>
> *[Install]*
> *WantedBy=multi-user.target*
>
> And in Myapp code my application is using fork() to create a child
> process. Because of which notification is not working correctly.
>
> This is error log
>
>
> *localhost systemd[1]: sd_example.service: Got notification message from
> PID 1270, but reception only permitted for main PID 1106*
>
> Is there any way from which we can force sd_notify to make use of Parent
> PID instead of child process. My sd_notify is after the fork() call, so I
> doubt sd_notify is called from child process.
>
> MyApp code snippet
>
>         *int count = 0;*
> *        cpid = fork();*
>
> *        if (cpid < 0)*
> *        {*
> *            printf("vfork failed.");*
> *        }*
>
> *        if (cpid == 0)*
> *        {*
> *            count++;*
> *            if(count == 1)*
> * {*
>
This notificaiton is done by the child process, but notificaitons are
accepted by default only form the main process. Read doc aobut
"NotifyAccess=".
https://www.freedesktop.org/software/systemd/man/systemd.service.html#NotifyAccess=

> * ret = sd_notify(0, "READY=1");*
> * printf("Return value = %d \n");*
> * }*
> * }*
>
>
> Regards,
> Raghavendra H R
>
> --
> Regards,
>
> Raghavendra. H. R
> (Raghu)
>
> On Tue, Nov 8, 2016 at 5:15 PM, Tomasz Torcz <tomek at pipebreaker.pl> wrote:
>
>> On Tue, Nov 08, 2016 at 05:01:59PM +0530, Raghavendra. H. R wrote:
>> > Hi All,
>> >
>> > I'm a newbie in Systemd init system and I'm exploring sd_notify which is
>> > basically used for notification purpose in SystemD.
>>
>>   It is written “systemd” (all lowercase).
>>
>> > I have created one unit file which is of type "notify" and in my
>> > application I have written sd_notify(0, "READY=1"); from which SystemD
>> can
>> > be notified that my process in totally up and running.
>> >
>> > Below given is my Service file.
>> >
>> > *[Unit]*
>> > *Description=Sd_notify example*
>> >
>> > *[Service]*
>> > *ExecStart=/etc/Myapp*
>>
>>
>>   This is not 'unit of type notify'. This is unit of type 'simple'.
>> Please read "man systemd.service" and paragraph Type= and choose
>> correctly.
>>
>>
>> > Need help in understanding what value should be set in the environment
>> > varaible NOTIFY_SOCKET.
>> > But there's no much information/documentation available on
>> NOTIFY_SOCKET.
>>
>>   NOTIFY_SOCKET is filled-in by systemd and it is available when you
>> correctly defined unit type.  If you want to check it's value, you can
>> user getenv() inside you program and print the value.
>>   I think amount of documentation about NOTIFY_SOCKET is enough, if
>> you think there's something specific missing, let us know.
>>
>>
>> --
>> Tomasz Torcz               "Never underestimate the bandwidth of a station
>> xmpp: zdzichubg at chrome.pl    wagon filled with backup tapes." -- Jim Gray
>>
>> _______________________________________________
>> systemd-devel mailing list
>> systemd-devel at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/systemd-devel
>>
>
>
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>
>


-- 

Alessandro Puccetti
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