configuration directory

[Andreas Ericsson]

On 2013-09-04 12:51, AL13N wrote:
>> On 2013-09-04 00:34, AL13N wrote:
>>> Op dinsdag 3 september 2013 17:22:32 schreef Andreas Ericsson:
>>>> On 2013-09-02 21:20, AL13N wrote:
>>>>> Hi,
>>>>>
>>>>> i'm a Mageia distribution packager, and i'm maintaining some event
>>>>> broker
>>>>> modules.
>>>>>
>>>>> since these are packaged seperately we're trying to get things to work
>>>>> out-of- the-box for our users, specifically adding event brokers in
>>>>> the
>>>>> configuration file for nagios.
>>>>>
>>>>> the problem we're facing is that: We don't want a nagios addon package
>>>>> to
>>>>> rewrite the configuration file itself. however, we would like to add
>>>>> the
>>>>> event broker (or other settings) and then reload/restart nagios.
>>>>>
>>>>> a beneficial thing would be a configuration directory (much like it
>>>>> exists
>>>>> with hosts and commands and stuff like that) but for the main nagios
>>>>> configuration file.
>>>>>
>>>>> and if while we're at it, to have multiple directories, where
>>>>> /usr/share/nagios/nagios.d/ has the "defaults" which can be overridden
>>>>> in
>>>>> /etc/nagios.d/ (for instance) (this is a convention that's growing in
>>>>> use)
>>>>>
>>>>> I can try to start making a patch for this, but i'm asking about this
>>>>> first, in order to find out if it makes a chance of getting accepted.
>>>>
>>>> Not only does it stand a chance of getting accepted; It's on the
>>>> roadmap. If you start working on it I'll help as much as I can and
>>>> I'm willing to accept less-than-awesome quality code, although I'll
>>>> polish such later if it turns out to be an issue.
>>>>
>>>> The only real requirement is that any "main" config file option
>>>> should be settable from any file in the dropdir.
>>>
>>>
>>> the idea i thought might be doable, would be to allow multiple -d
>>> options to
>>> nagios, and allow those to be a file or a directory.
>>>
>>
>> I'd much rather see this as "include=/some/path.d" where we read all
>> files ending with .cfg and .conf if it's a directory, or the file if
>> it's a fail, and then parse each include'd file in order of
>>     include-statement -> lexicographical order
>> so that
>>
>> include=/etc/nagios.conf.d/
>> include=/etc/nagios.perfdata.d/
>>
>> would cause all files from /etc/nagios.conf.d to be parsed before all
>> files from /etc/nagios.perfdata.d.
>>
>> The included files can include other files, if they're so inclined.
>
> so, you mean to keep one nagios.cfg file and have include=/path/to/foo.
>
> would this mean that if you have
>
> setting1=value
>
> setting2=value
>
> include=/path/to/foo
>
> setting3=value
>
> that being parsed would:
> 1) setting1
> 2) setting2
> 3) all from /path/to/foo if it's a file or directory
> 4) setting3
>
>
> is this the priority that you aim for?
>

No. All variables from one file should be parsed before any variables
from a different file, but the include-files from one file get parsed
before we move along to the next file in that directory.

If we pretend that /etc/nagios/conf.d contains two files, named A.cfg
and B.cfg, where A.cfg has "include=/etc/nagios/perfdata.cfg" and the
main nagios config file is /etc/nagios/nagios.cfg, but one also wants
to oneshot parse /etc/nagios/debug.cfg, then one would execute Nagios
like so:

   nagios -d /etc/nagios/nagios.cfg /etc/nagios/debug.cfg

and with the above settings we would parse
/etc/nagios/nagios.cfg nagios.cfg (all settings)
/etc/nagios/conf.d/A.cfg (all settings)
/etc/nagios/perfdata.cfg (all settings)
/etc/nagios/conf.d/B.cfg (all settings)
/etc/nagios/debug.cfg (all settings)

In practice though, I expect the default settings will be so that
/etc/nagios/nagios.cfg contains this:
include=/etc/nagios/defaults.cfg
include=/etc/nagios/conf.d

Btw, we shouldn't error out when encountering an empty directory,
but rather just print a warning about it. Or even have "include_dir"
and "include_file", where both cause an error if the targeted path
doesn't exist, although we allow empty directories.

I just realized that this includes the "parse multiple config files
from command-line", but since that's hardly a difficult issue once
we can parse multiple config files, I doubt that's a problem.

-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231

Considering the successes of the wars on alcohol, poverty, drugs and
terror, I think we should give some serious thought to declaring war
on peace.

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