[syslog-ng] [PATCH] syslog-ng: Add a -q/--silent-module-load option

[Gergely Nagy]

Balazs Scheidler <bazsi at balabit.hu> writes:

> On Sat, 2011-10-15 at 10:59 +0200, Gergely Nagy wrote:
>> With the -q/--silent-module-load option set (defaults to off), no
>> warnings will be printed when a module cannot be found.
>> 
>> If it's found, but cannot be loaded, a message is still printed. If it
>> is used later in the config, that's still handled correctly.
>> 
>> The flag only suppresses the warning, and nothing else.
>
> I'm not sure why you'd want to do this, could you elaborate? Thanks.

The main reason is that syslog-ng 3.2 in Debian has all modules in a
single package, but with 3.3, they're going to be split out into
separate packages (with the syslog-ng package depending on -core and the
-modules).

And the default modules to load was therefore set to only those modules
that remained in the -core package, so that configs that do not use,
say, SQL, won't try to load afsql module, and emit a warning each time
syslog-ng is started up. Instead, the module packages provide a file
under /etc/syslog-ng/conf.d/, which is sourced by the updated
syslog-ng.conf.

However, there was one case I did not consider: when the user modified
syslog-ng.conf already, the include did not get added, and thus, when
upgrading, the afsql module wasn't loaded. If they used SQL
destinations, then the upgrade broke, because syslog-ng wouldn't start
up.

To work around this issue, the best idea I could come up with, is to
re-enable the afsql module by default. But that would result in a module
not found warning when the appropriate package is not installed.

So, I figured it'd be a reasonable middleground to add a flag that stops
the warning from being printed: if a module is not found, and is not
used, so be it. If it would be used, syslog-ng will error out later
anyway.

All in all, my reason for the flag is to silence a warning in case we
know that we'll try to load modules that may or may not be installed,
and we don't really care about it, if they're not there, and aren't used
anyway.

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