Salt: cron.present should support magic string @reboot

[rhertzog]

cron supports using some special strings replacing the first five time matching fields:

       Instead of the first five fields, one of eight special strings may appear:

              string         meaning
              ------         -------
              @reboot        Run once, at startup.
              @yearly        Run once a year, "0 0 1 1 *".
              @annually      (same as @yearly)
              @monthly       Run once a month, "0 0 1 * *".
              @weekly        Run once a week, "0 0 * * 0".
              @daily         Run once a day, "0 0 * * *".
              @midnight      (same as @daily)
              @hourly        Run once an hour, "0 * * * *".

The @reboot one is special and can't be emulated with the 5 usual fields thus it would be nice if there was a way for cron.present to use it.

[thatch45]

Thanks for the heads up, I thought we had that one in there!
should not be hard to add since the scaffolding is already there

[terminalmage]

Not all cron daemons support this, so it would be prudent to do some OS detection with grains before adding this to the crontab.

[techhat]

Is there a reasonable way to check the installed cron package, instead of the OS? It's pretty easy to swap out cron daemons, and Arch users especially have been known to do it.

[terminalmage]

Good point. It should be easy enough to come up with a list of package names for cron daemons which support it, and run a check against that list.

[sjorge]

Looks like this has been implemented

[didip]

@sjorge Do you happen to have an example snippet on how to use @reboot? I'd appreciate it.

[sjorge]

@didip I only have one location where I use it:

network.route::lx-helper:
  file.directory:
    - name: /etc/inet
  cron.present:
    - name: /native/usr/bin/awk '!/^($|[:space:]*#)/{ print "/native/usr/sbin/route add "$0 }' /etc/inet/static_routes | sh
    - special: '@reboot'

But it's a very specific usage, in my case due to some lacking tooling support when running Ubuntu/CentOS under SmartOS using lxbranded zones... the routes are missing after a reboot. I inject them using a cron that fires on @reboot.

[didip]

Thanks! That special keyword is all I need.

[ghost]

Was this ever implemented? I get the following error when trying to use special:

Warnings: 'special' is an invalid keyword argument for 'cron.present'. If
          you were trying to pass additional data to be used in a template
          context, please populate 'context' with 'key: value' pairs. Your
          approach will work until Salt Carbon is out. Please update your
          state files.

[sjorge]

@grobinson-blockchain it seems to work fine (on linux) under 2016.3, not sure about earlier.

[MTecknology]

Wow! I just spent a long time fighting this. It turns out - special: @reboot which was wrong. In some incantations of this line, I was able to produce an error, but most just created the cron entry with no comment identifier and no "@" at the beginning of the line and re-executions created another similar line.

The only incantation that works is when @reboot is inside of quotes. This probably /shouldn't/ require quotes, but maybe using @ means it's needed because of yaml. It would be nice if - special: reboot added the "@" and anything else that won't work just generated an error.

[lordcirth]

From Wikipedia: "Two additional sigil characters are reserved in YAML for possible future standardisation: the at sign (@) and accent grave (`)."

So yes, the @ sign is being stripped. I'm not sure that some code to recognize strings that should have @ signs is needed, that sounds clunky. I think a documentation change to remind the user to use quotes would be sufficient.

[rallytime]

Thank you all for the discussion here. Since the special option has been implemented and @lordcirth has now updated the documentation, I'll close this.