Use bind-dirs to handle crontab persistence

[jbwells]

Qubes OS version (e.g., R3.1):

R3.2-rc2

Affected TemplateVMs (e.g., fedora-23, if applicable):

AppVM using debian-8 TemplateVM

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Expected behavior:

Whenever cron is running, it should obey a crontab installed via the crontab program. It should also be possible to remove a crontab while cron is not running.

Actual behavior:

Crontab files installed while cron is not running are hidden by a directory mounted over them when cron is started.

Steps to reproduce the behavior:

sudo systemctl stop cron
crontab FILE
sudo systemctl start cron

General notes:

See /lib/systemd/system/cron.service.d/30_qubes.conf.

This is very confusing when trying to debug why your cron jobs are not running!

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Related issues:

[jbwells]

I forgot to mention: This problem also mean that you can not configure cron jobs in the TemplateVM that will run in AppVMs based on it.

[jbwells]

I forgot to mention: This problem also mean that you can not configure cron jobs in the TemplateVM that will run in AppVMs based on it.

[unman]

@jbwells @andrewdavidwong

This isn't a Debian specific issue, and I'm not convinced it's a bug - it's a feature of the normal Qubes treatment of template based qubes. The statement of expected behaviour seems to me to be inappropriate for Qubes.
The use of /rw/cron enables something approaching a standard use of cron. Since a standard crontab file would disappear on reboot, the /rw/cron files enable cron jobs to persist for a template based qube.

It is possible to configure cron jobs in a Template, using the /rw/cron mechanism, and they will run in any qube created using that template. Like changes in /home, later editing of files on the template will not feed through to the qube after it has been created.

[unman]

@jbwells @andrewdavidwong

This isn't a Debian specific issue, and I'm not convinced it's a bug - it's a feature of the normal Qubes treatment of template based qubes. The statement of expected behaviour seems to me to be inappropriate for Qubes.
The use of /rw/cron enables something approaching a standard use of cron. Since a standard crontab file would disappear on reboot, the /rw/cron files enable cron jobs to persist for a template based qube.

It is possible to configure cron jobs in a Template, using the /rw/cron mechanism, and they will run in any qube created using that template. Like changes in /home, later editing of files on the template will not feed through to the qube after it has been created.

[andrewdavidwong]

I can see the arguments on both sides. Ultimately, this may be more of a feature request than a bug report. @marmarek?

[andrewdavidwong]

I can see the arguments on both sides. Ultimately, this may be more of a feature request than a bug report. @marmarek?

[marmarek]

Since we have bind-dirs, it should be quite easy to move that cron handling

[marmarek]

Since we have bind-dirs, it should be quite easy to move that cron handling

[adrelanos]

@marmarek QubesOS/qubes-doc#199 (comment)

I think it would be better to package bind-dirs configuration for cron, as part of QubesOS/qubes-core-agent-linux#19, instead of relying on user to manually do it.

[adrelanos]

@marmarek QubesOS/qubes-doc#199 (comment)

I think it would be better to package bind-dirs configuration for cron, as part of QubesOS/qubes-core-agent-linux#19, instead of relying on user to manually do it.

[marmarek]

It's done.

[marmarek]

It's done.