Debian Bug report logs - #783683
restarting cron kills running jobs

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: Joerg Morbitzer <jomo@sol-3.de>

To: Debian Bug Tracking System <submit@bugs.debian.org>

Subject: cron started with -f (foreground), killing processes on restart

Date: Wed, 29 Apr 2015 09:28:44 +0200

Package: cron
Version: 3.0pl1-127
Severity: normal

Dear Maintainer,

on Debian Jessie the cron daemon is being started with the parameter -f
(for running in "foreground"). Now, when restarting the daemon using
"systemctl restart cron.service" all running processes *initiated*
by the cron daemon will be killed.

I think the culprit is in this file:

/lib/systemd/system/cron.service

sol3@leeds:~$ ps auxww | grep '[c]ron'
root      8694  0.0  0.0  27464  2644 ?        Ss   Apr28   0:00 /usr/sbin/cron -f
sol3@leeds:~$

In the past (with Squeeze, Wheezy etc.) cron was always daemonized
and that behaviour never(!) happened, I think this -f is a pretty 
dangerous thing.

Kind regards, Joerg Morbitzer


-- Package-specific info:
--- EDITOR:


--- /usr/bin/editor:
/usr/bin/vim.gtk

--- /usr/bin/crontab:
-rwxr-sr-x 1 root crontab 36008 Oct 26  2014 /usr/bin/crontab

--- /var/spool/cron:
drwxr-xr-x 5 root root 4096 Jan 28 11:44 /var/spool/cron

--- /var/spool/cron/crontabs:
drwx-wx--T 2 root crontab 4096 Mar 27 09:37 /var/spool/cron/crontabs

--- /etc/cron.d:
drwxr-xr-x 2 root root 4096 Jan 28 11:45 /etc/cron.d

--- /etc/cron.daily:
drwxr-xr-x 2 root root 4096 Apr 20 07:03 /etc/cron.daily

--- /etc/cron.hourly:
drwxr-xr-x 2 root root 4096 Jan 28 11:40 /etc/cron.hourly

--- /etc/cron.monthly:
drwxr-xr-x 2 root root 4096 Jan 28 11:45 /etc/cron.monthly

--- /etc/cron.weekly:
drwxr-xr-x 2 root root 4096 Jan 28 11:45 /etc/cron.weekly


-- System Information:
Debian Release: 8.0
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.16.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Init: systemd (via /run/systemd/system)

Versions of packages cron depends on:
ii  adduser              3.113+nmu3
ii  debianutils          4.4+b1
ii  dpkg                 1.17.25
ii  init-system-helpers  1.22
ii  libc6                2.19-18
ii  libpam-runtime       1.1.8-3.1
ii  libpam0g             1.1.8-3.1
ii  libselinux1          2.3-2
ii  lsb-base             4.1+Debian13+nmu1

Versions of packages cron recommends:
ii  exim4                                      4.84-8
ii  exim4-daemon-light [mail-transport-agent]  4.84-8

Versions of packages cron suggests:
ii  anacron        2.3-23
pn  checksecurity  <none>
ii  logrotate      3.8.7-1+b1

Versions of packages cron is related to:
pn  libnss-ldap   <none>
pn  libnss-ldapd  <none>
pn  libpam-ldap   <none>
pn  libpam-mount  <none>
ii  nis           3.17-33
pn  nscd          <none>

-- no debconf information

Message #10 received at 783683@bugs.debian.org (full text, mbox, reply):

From: Alexandre Detiste <alexandre.detiste@gmail.com>

To: 783683@bugs.debian.org

Subject: Re: cron started with -f (foreground), killing processes on restart

Date: Fri, 01 May 2015 09:24:41 +0200

Control: severity -1 important


Hi,

To solve your problem, you can add "KillMode=process" 
into the [Service] stanza of cron.service.

I guess this is an important bug that should be solved in Debian 8.1
due soon.


---

http://www.freedesktop.org/software/systemd/man/systemd.kill.html

| If set to control-group, all remaining processes in the control group of this unit will be killed on unit stop
| If set to process, only the main process itself is killed.
| Defaults to control-group.

Other distro's do that too

https://git.fedorahosted.org/cgit/cronie.git/tree/contrib/cronie.systemd
http://arch-general.archlinux.narkive.com/FcUpb8Nw/protect-a-cron-job-from-systemd

(not Debian)
http://anonscm.debian.org/cgit/pkg-cron/pkg-cron.git/tree/debian/cron.service

Alexandre Detiste

Message #15 received at 783683@bugs.debian.org (full text, mbox, reply):

From: Christoph Berg <myon@debian.org>

To: Joerg Morbitzer <jomo@sol-3.de>, 783683@bugs.debian.org, Alexandre Detiste <alexandre.detiste@gmail.com>

Subject: Re: Bug#783683: cron started with -f (foreground), killing processes on restart

Date: Sun, 3 May 2015 14:58:07 +0200

[Message part 1 (text/plain, inline)]

Control: severity -1 critical

Re: Joerg Morbitzer 2015-04-29 <20150429072844.9034.66226.reportbug@mars.sol-3.de>
> In the past (with Squeeze, Wheezy etc.) cron was always daemonized
> and that behaviour never(!) happened, I think this -f is a pretty 
> dangerous thing.

The problem isn't running in the foreground, but systemd's process
group handling.


Re: Alexandre Detiste 2015-05-01 <2522456.jJ8AmF7lJg@antec>
> Control: severity -1 important
> 
> 
> Hi,
> 
> To solve your problem, you can add "KillMode=process" 
> into the [Service] stanza of cron.service.
> 
> I guess this is an important bug that should be solved in Debian 8.1
> due soon.

The behavior was different for decades, and this change isn't
mentioned in NEWS.Debian to make the user aware. I guess everyone who
has been managing cron as a sysadmin will get bitten badly by this
change.

I'd strongly opt to change the KillMode as mentioned above.
#debian-devel seems to agree, so I'm upgrading this bug to RC.
(critical as it's killing "random" processes)

> http://www.freedesktop.org/software/systemd/man/systemd.kill.html
> 
> | If set to control-group, all remaining processes in the control group of this unit will be killed on unit stop
> | If set to process, only the main process itself is killed.
> | Defaults to control-group.
> 
> Other distro's do that too
> 
> https://git.fedorahosted.org/cgit/cronie.git/tree/contrib/cronie.systemd
> http://arch-general.archlinux.narkive.com/FcUpb8Nw/protect-a-cron-job-from-systemd
> 
> (not Debian)
> http://anonscm.debian.org/cgit/pkg-cron/pkg-cron.git/tree/debian/cron.service

Christoph
-- 
cb@df7cb.de | http://www.df7cb.de/

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Message #22 received at 783683@bugs.debian.org (full text, mbox, reply):

From: Christoph Berg <myon@debian.org>

To: Joerg Morbitzer <jomo@sol-3.de>, 783683@bugs.debian.org, Alexandre Detiste <alexandre.detiste@gmail.com>

Subject: Re: Bug#783683: cron started with -f (foreground), killing processes on restart

Date: Sun, 3 May 2015 15:33:45 +0200

[Message part 1 (text/plain, inline)]

Re: To Joerg Morbitzer 2015-05-03 <20150503125807.GA3116@msg.df7cb.de>
> > I guess this is an important bug that should be solved in Debian 8.1
> > due soon.
> 
> The behavior was different for decades, and this change isn't
> mentioned in NEWS.Debian to make the user aware. I guess everyone who
> has been managing cron as a sysadmin will get bitten badly by this
> change.
> 
> I'd strongly opt to change the KillMode as mentioned above.
> #debian-devel seems to agree, so I'm upgrading this bug to RC.
> (critical as it's killing "random" processes)

A particular reason why the current behavior is bad is that it is
common practise to start user daemons using @reboot cronjobs. These
are long-running and shouldn't get terminated. (There are alternatives
available to start user processes at boot, but the predominant way atm
is still @reboot.)

Christoph
-- 
cb@df7cb.de | http://www.df7cb.de/

[signature.asc (application/pgp-signature, inline)]

Message #27 received at 783683@bugs.debian.org (full text, mbox, reply):

From: Christian Kastner <debian@kvr.at>

To: Christoph Berg <myon@debian.org>

Cc: Joerg Morbitzer <jomo@sol-3.de>, 783683@bugs.debian.org, Alexandre Detiste <alexandre.detiste@gmail.com>

Subject: Re: Bug#783683: cron started with -f (foreground), killing processes on restart

Date: Sun, 03 May 2015 15:47:04 +0200

Control: tag -1 + confirmed pending

On 2015-05-03 15:33, Christoph Berg wrote:
> Re: To Joerg Morbitzer 2015-05-03 <20150503125807.GA3116@msg.df7cb.de>
>> I'd strongly opt to change the KillMode as mentioned above.
>> #debian-devel seems to agree, so I'm upgrading this bug to RC.
>> (critical as it's killing "random" processes)
> 
> A particular reason why the current behavior is bad is that it is
> common practise to start user daemons using @reboot cronjobs.

I was wondering what the use case for this was, but that seems plausible.

Regardless, I committed a fix for the sole fact that it's a significant
deviation from past behavior, as you pointed out.

I've prepared packages for both jessie and unstable.

Thanks, Alexandre and Christoph, for your analysis and solution!

Regards,
Christian

Message #34 received at 783683-close@bugs.debian.org (full text, mbox, reply):

From: Christian Kastner <debian@kvr.at>

To: 783683-close@bugs.debian.org

Subject: Bug#783683: fixed in cron 3.0pl1-128

Date: Thu, 14 May 2015 07:34:04 +0000

Source: cron
Source-Version: 3.0pl1-128

We believe that the bug you reported is fixed in the latest version of
cron, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 783683@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Christian Kastner <debian@kvr.at> (supplier of updated cron package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

Format: 1.8
Date: Sun, 03 May 2015 15:25:18 +0200
Source: cron
Binary: cron
Architecture: source i386
Version: 3.0pl1-128
Distribution: unstable
Urgency: medium
Maintainer: Javier Fernández-Sanguino Peña <jfs@debian.org>
Changed-By: Christian Kastner <debian@kvr.at>
Description:
 cron       - process scheduling daemon
Closes: 783683
Changes:
 cron (3.0pl1-128) unstable; urgency=medium
 .
   * d/cron.service: Use KillMode=process to kill only the daemon.
     The default of KillMode=control-group kills all the processes in the control
     group, for example when restarting the daemon. This is a deviation from past
     behavior we do not want. Thanks, Alexandre Detiste! Closes: #783683
Checksums-Sha1:
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Message #37 received at 783683@bugs.debian.org (full text, mbox, reply):

From: Christoph Berg <myon@debian.org>

To: Christian Kastner <debian@kvr.at>, 783683@bugs.debian.org

Cc: Joerg Morbitzer <jomo@sol-3.de>, Alexandre Detiste <alexandre.detiste@gmail.com>

Subject: Re: Bug#783683: cron started with -f (foreground), killing processes on restart

Date: Sat, 6 Jun 2015 21:33:24 +0200

[Message part 1 (text/plain, inline)]

Re: Christian Kastner 2015-05-03 <554626D8.4090906@kvr.at>
> >> I'd strongly opt to change the KillMode as mentioned above.
> >> #debian-devel seems to agree, so I'm upgrading this bug to RC.
> >> (critical as it's killing "random" processes)
> > 
> > A particular reason why the current behavior is bad is that it is
> > common practise to start user daemons using @reboot cronjobs.
> 
> I was wondering what the use case for this was, but that seems plausible.
> 
> Regardless, I committed a fix for the sole fact that it's a significant
> deviation from past behavior, as you pointed out.
> 
> I've prepared packages for both jessie and unstable.

Hi,

I had hoped to see this fixed in today's point release. What happened
with the jessie package?

Christoph
-- 
cb@df7cb.de | http://www.df7cb.de/

[signature.asc (application/pgp-signature, inline)]

Message #42 received at 783683@bugs.debian.org (full text, mbox, reply):

From: Christian Kastner <debian@kvr.at>

To: Christoph Berg <myon@debian.org>, 783683@bugs.debian.org, Joerg Morbitzer <jomo@sol-3.de>, Alexandre Detiste <alexandre.detiste@gmail.com>

Subject: Re: Bug#783683: cron started with -f (foreground), killing processes on restart

Date: Sun, 07 Jun 2015 18:30:03 +0200

Hi,

On 2015-06-06 21:33, Christoph Berg wrote:
> Re: Christian Kastner 2015-05-03 <554626D8.4090906@kvr.at>
>>>> I'd strongly opt to change the KillMode as mentioned above.
>>>> #debian-devel seems to agree, so I'm upgrading this bug to RC.
>>>> (critical as it's killing "random" processes)
>>>
>>> A particular reason why the current behavior is bad is that it is
>>> common practise to start user daemons using @reboot cronjobs.
>>
>> I was wondering what the use case for this was, but that seems plausible.
>>
>> Regardless, I committed a fix for the sole fact that it's a significant
>> deviation from past behavior, as you pointed out.
>>
>> I've prepared packages for both jessie and unstable.
> 
> I had hoped to see this fixed in today's point release. What happened
> with the jessie package?

I'm afraid I couldn't get a hold of Javier regarding an upload. I myself
don't have upload rights yet.

I meant to take care of this before I went AFK for the weekend, but I
forgot about this :-/ If an upload to jessie-p-u is still a possibility
and you'd like to sponsor, a package for jessie has been prepared on the
"jessie" branch. It was already ACKed by the RT, see #785573.

Regards,
Christian

Message #47 received at 783683@bugs.debian.org (full text, mbox, reply):

From: Javier Fernandez-Sanguino <jfs@computer.org>

To: Christian Kastner <debian@kvr.at>, 783683@bugs.debian.org

Cc: Christoph Berg <myon@debian.org>, Joerg Morbitzer <jomo@sol-3.de>, Alexandre Detiste <alexandre.detiste@gmail.com>

Subject: Re: Bug#783683: cron started with -f (foreground), killing processes on restart

Date: Sun, 7 Jun 2015 22:32:41 +0200

[Message part 1 (text/plain, inline)]

On 7 June 2015 at 18:30, Christian Kastner <debian@kvr.at> wrote:

> On 2015-06-06 21:33, Christoph Berg wrote:
>
> > I had hoped to see this fixed in today's point release. What happened
> > with the jessie package?
>
> I'm afraid I couldn't get a hold of Javier regarding an upload. I myself
> don't have upload rights yet.
>

My fault. Quite simply: life got in the way.


> I meant to take care of this before I went AFK for the weekend, but I
> forgot about this :-/ If an upload to jessie-p-u is still a possibility
> and you'd like to sponsor, a package for jessie has been prepared on the
> "jessie" branch. It was already ACKed by the RT, see #785573.
>

I am going to do this right away. I'm building the origin/jessie branch as
I'm writing this.

Regards

Javier

[Message part 2 (text/html, inline)]

Message #52 received at 783683-close@bugs.debian.org (full text, mbox, reply):

From: Christian Kastner <debian@kvr.at>

To: 783683-close@bugs.debian.org

Subject: Bug#783683: fixed in cron 3.0pl1-127+deb8u1

Date: Thu, 11 Jun 2015 06:47:07 +0000

Source: cron
Source-Version: 3.0pl1-127+deb8u1

We believe that the bug you reported is fixed in the latest version of
cron, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 783683@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Christian Kastner <debian@kvr.at> (supplier of updated cron package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

Format: 1.8
Date: Sun, 03 May 2015 15:25:18 +0200
Source: cron
Binary: cron
Architecture: source i386
Version: 3.0pl1-127+deb8u1
Distribution: jessie
Urgency: medium
Maintainer: Javier Fernández-Sanguino Peña <jfs@debian.org>
Changed-By: Christian Kastner <debian@kvr.at>
Description:
 cron       - process scheduling daemon
Closes: 783683
Changes:
 cron (3.0pl1-127+deb8u1) jessie; urgency=medium
 .
   * d/cron.service: Use KillMode=process to kill only the daemon.
     The default of KillMode=control-group kills all the processes in the control
     group, for example when restarting the daemon. This is a deviation from past
     behavior we do not want. Thanks, Alexandre Detiste! Closes: #783683
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Message #57 received at 783683@bugs.debian.org (full text, mbox, reply):

From: "Margarita Manterola" <marga@debian.org>

To: 783683@bugs.debian.org

Subject: Unattended upgrades to 3.0pl1-127+deb8u1 will break

Date: Sat, 13 Jun 2015 10:02:17 +0000

HI,

An "interesting" consequence of this bug is that unattended upgrades are
triggered from cron, so when the cron package is automatically upgraded to the
latest version, the upgrade gets killed and leaves the cron package in a broken
state that "configure -a" doesn't fix but "dpkg -i cron.deb" does.     
                                                                       
I don't know if there was a way of not causing this, but it's extremely
unfortunate as this means any machine using unattended upgrades has it's cron
package already in a broken state that requires manual action to fix.

Regards,
Marga

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