If I recall correctly, the NullAppender is there mainly to avoid ClassLoader errors during shutdown in certain scenarios (e.g., shutdown before any appenders were initialized, so the class might not be loaded yet).
On Sun, 16 Sep 2018 at 12:03, Gary Gregory <garydgreg...@gmail.com> wrote: > On Sat, Sep 15, 2018 at 5:22 PM Gary Gregory <garydgreg...@gmail.com> > wrote: > > > > > > > On Sat, Sep 15, 2018 at 5:16 PM Gary Gregory <garydgreg...@gmail.com> > > wrote: > > > >> > >> > >> On Sat, Sep 15, 2018 at 4:43 PM Gary Gregory <garydgreg...@gmail.com> > >> wrote: > >> > >>> On Sat, Sep 15, 2018 at 4:40 PM Ralph Goers < > ralph.go...@dslextreme.com> > >>> wrote: > >>> > >>>> If you don’t want to log anything then enable a noop appender that > just > >>>> returns without doing anything > >>>> > >>> > >>> Oh, I see we already have a NullAppender... > >>> > >> > >> So I can do: > >> > >> <ScriptAppenderSelector name="SelectIt"> > >> <Script language="JavaScript"><![CDATA[ > >> ##SPECIAL_THING##]]> > >> </Script> > >> <AppenderSet> > >> <RollingFileAppender name="MyAppender" ... /> > >> <Null/> > >> </AppenderSet> > >> </ScriptAppenderSelector> > >> > >> Not quite as simple as: > >> > >> <RollingFileAppender name="MyAppender" enable="##SPECIAL_THING##" ... /> > >> > >> I often times have to walk our users through some configs so option 2 is > >> simpler for them and less error prone... but option 1 will work for > now... > >> > > > > The not great thing here is that for each appender I want to be able to > > toggle, I have to repeat this pattern... > > > > I have something working, if ponderously, using the ScriptAppenderSelector. > After looking at all the configs I had to update, it seems that supporting > an "enabled" attribute would be much cleaners. > > Gary > > > > Gary > > > >> > >> Gary > >> > >> > >>> > >>> Gary > >>> > >>> > >>>> > >>>> Sent from my iPhone > >>>> > >>>> > On Sep 15, 2018, at 12:34 PM, Gary Gregory <garydgreg...@gmail.com> > >>>> wrote: > >>>> > > >>>> > On Sat, Sep 15, 2018 at 3:24 PM Ralph Goers < > >>>> ralph.go...@dslextreme.com> > >>>> > wrote: > >>>> > > >>>> >> We have an appended selector for this. Why not us it? > >>>> >> > >>>> > > >>>> > Hi, > >>>> > > >>>> > Because: > >>>> > - Conceptually, I am not selecting an appender out of a set, I want > >>>> the one > >>>> > appender enabled or disabled. > >>>> > - In practice, using a ScriptAppenderSelector with a single Appender > >>>> means > >>>> > my script would have to 'select' a non-existing appender when the > >>>> script > >>>> > evaluates to false, which would work BUT would emit an ERROR log > >>>> event to > >>>> > the status logger like "No node named DISABLE_ME in > >>>> > NameOfScriptAppenderSelector". This would be a normal configuration, > >>>> so an > >>>> > ERROR would be very bad for our users. Changing the level of event > >>>> would > >>>> > not help, unless it was buried at the DEBUG level, which is not good > >>>> for > >>>> > the current use cases. > >>>> > - Alternatively, we could have add a NoOpAppender which I would then > >>>> select > >>>> > when I want the file appender disabled. This would imply accepting > the > >>>> > added costs, no matter how minor in memory and speed. > >>>> > > >>>> > Thoughts? > >>>> > > >>>> > Gary > >>>> > > >>>> > > >>>> >> > >>>> >> Sent from my iPhone > >>>> >> > >>>> >>> On Sep 15, 2018, at 11:07 AM, Gary Gregory < > garydgreg...@gmail.com> > >>>> >> wrote: > >>>> >>> > >>>> >>> Hi All: > >>>> >>> > >>>> >>> At work, we have an installer program that installs one of five > >>>> log4j > >>>> >>> configs depending on what the user selects in a UI. Each of these > 5 > >>>> >> configs > >>>> >>> causes log events to end up in different kinds of SQL and NoSQL > >>>> >> databases, > >>>> >>> you pick one when you install. The installer does a brute force > >>>> search > >>>> >> and > >>>> >>> replace in the log4j file to replace markers with things like > >>>> database IP > >>>> >>> addresses and port numbers. So far so simple and good. > >>>> >>> > >>>> >>> The next iteration of the installer provides an additional choice > >>>> to log > >>>> >> to > >>>> >>> a file or not, in addition of one of the 5 databases. > >>>> >>> > >>>> >>> Option 1? > >>>> >>> In order to avoid having 5x2 preset config files in the installer, > >>>> I'd > >>>> >> like > >>>> >>> to add the file config to each of the existing 5 configurations > and > >>>> have > >>>> >>> the file appender enabled or not based on a boolean flag that the > >>>> >> installer > >>>> >>> can implement as part of its search and replace. You'd end up > with: > >>>> >>> > >>>> >>> <AppenderRef ref="foo" enabled="true|false" /> > >>>> >>> <AppenderFoo enabled="true|false" /> > >>>> >>> > >>>> >>> If an appender is disabled it does not end up in the Log4j object > >>>> tree at > >>>> >>> all. It is like it never existed in the config file. > >>>> >>> > >>>> >>> Option 2? > >>>> >>> Add a second log4j2.xml, say log4j2-rollingfile.xml config file > and > >>>> have > >>>> >>> Log4j combine it with the other log4j.xml on the class path. How? > >>>> >>> > >>>> >>> Other options? > >>>> >>> > >>>> >>> Thank you, > >>>> >>> Gary > >>>> >> > >>>> >> > >>>> > >>>> > >>>> > -- Matt Sicker <boa...@gmail.com>
