RE: Locking for temporary ad-hoc changes?

[David Masterson]

Wil Cooley wrote:
> One situation I come across all too often is the need to make ad-hoc
> changes on a system before pushing them through Subversion and back
> into proper place through cfengine.  Apache config files, for example,
> sometimes take a few tries to get just right.  My setups are not big
> or sophisticated enough to have real test servers, which is fine for
> the most part.
> 
> What happens is that I'm editing my config file and cfagent makes its
> scheduled run, notices the file is changed and the replaces it.  I
> tend, as a result, to suspend my editor session while making changes
> so if it happens I can resume and rewrite my changed version.  What
> seems like it would be fairly straightforward to implement would be a
> user-initiated locking mechanism, so that a locked file would not be
> updated but an alert generated that the file was wrong
> date/checksum/etc.  Something like this:
> 
> # cflock /etc/httpd/conf.d/foo.conf
> # vi /etc/httpd/conf.d/foo.conf
> # cflock -u /etc/httpd/conf.d/foo.conf
> 
> (Maybe a 'cflock -l' to list locks would be useful too.)
> 
> Of course, getting these changes back to my repo is also on my
> wishlist, but much bigger and less straightforward.

Sounds like you should setup your "update.conf" to do something like the
following:

1. Check if the master config files are newer than the local one -- copy if
necessary.
2. Check if /var/cfengine/config config files are newer than the local one --
copy if necessary.
3. Check if /var/cfengine/inputs config files are newer than
/var/cfengine/configs -- copy if necessary.

Then, if you need to make a local change, modify the file in
/var/cfengine/config and let cfagent pick it up on it's next run.

-- 
David Masterson
VMware, Inc.
Palo Alto, CA