Hi, I've worked on plenty of serious apps with log4net and as far as I know we've never had a need to change the logfile at runtime. Why would you need to change the logfile?
We've normally regarded the logging information as static information which requires a redeployment to change. In our case, live deployments are easy and cheap, and there is no requirement (business or technical) for runtime modification of logging configuration, so this approach works well. Certainly it keeps the logging easy to understand. I do not think it's correct to say that only Mickey Mouse apps have logging configuration that cannot be changed at runtime. Regards, Tristan. On Sun, Nov 10, 2013 at 11:07 AM, Greg Keogh <[email protected]> wrote: > Folks, this post is partly a reminder to myself and anyone else who goes > through the searching and suffering of how to configure log4net at runtime. > Log4net is well featured, but web is fully of "kiddy" examples that only use > xml config files, and any serious app is going to have to change things at > runtime. The classic problem for me was how to change the path of the > rolling log file. > > One guy says for web apps to put file="~/App_Data/foo.log". I didn't try > this but I found that %environment% variables don't work. I still haven't > found a clear definition of just what "variables" or special tokens are > recognised in xml elements. > > Some people suggest that you create the appender at runtime, but the code is > ugly as sin. Others tell you to find the appender in the collection, change > the property value and ActivateOptions(), which works, but it leaves a zero > length file of the original file name. Someone else tried putting > file="%property{myname}" but it didn't replace the global property value. > This last attempt was nearly there and I finally found someone's tweak to > make it work. Here's the answer: > > <appender name="Roller" ...> > <file type="log4net.Util.PatternString" > value="%property{rollpath}\zroll.log" /> > : > </appender> > > string rollpath = Path.Combine(... whatever you need...); > log4net.GlobalContext.Properties["rollpath"] = rollpath; > log4net.Config.XmlConfigurator.Configure(); > > The subtle fix is the bit I highlighted and it's damn easy to miss. Lord > knows how many other obscure "fixes" I'll be looking for. > > Greg K
