[packagekit] running without a head via cron

[Matthew Miller]

On Tue, Mar 04, 2008 at 03:21:42PM +0000, Richard Hughes wrote:
> Patch attached allows PackageKit to be optionally run once a day using
> cron. Is this sane? I think it's quite useful on the headless server use
> case and it's trivial to add.

So, this is basically what Sveta is working on here at BU. We've currently
got a big ol' shell script which runs yum periodically, and we're looking to
move away from that.

There's some significant advantages in having your controlling program (i.e.
that which gets run from cron) be something other than a shell script. 

1) Error handling. If something goes wrong, we want a different message than
   for success -- different subject, different body, etc. Plus, there's many
   different types of errors (network problems, repo problems, local package
   db problems, etc.) which need different responses.

2) Dealing with network transiency. This is a big enough issue that I want
   to highlight it separately from error handling in general. Network errors
   may be temporary, in which case we don't want to send out too many
   annoying messages, but we may want to log a warning if they go on for too
   long.

3) Formatting output. Generally, utilities designed for command-line use
   don't have output that's idea for e-mail. And, we probably want to also
   have the option of sending HTML mail. But for obvious curmudgeonly
   sysadmin reasons this must be optional.

4) Avoiding writing temporary files for mail output. Temporary files just
   add a whole 'nuther category of potential failures. (What if updates are
   broken because /var is full?)

5) Creeping feature doom. It'd be nice to be able to set which repos get
   updated automatically, which get only security updates, which get only
   notification. Handling that in a shell script gets crazier and crazier.

There's probably more. That's off the top of my head. :)

So, I think it's ideal to not call a designed-for-the-CLI frontend from a
shell script, but rather replace the shell script with a
designed-for-background program.
   
-- 
Matthew Miller           mattdm at mattdm.org          <http://mattdm.org/>
Boston University Linux      ------>              <http://linux.bu.edu/>