[logback-user] Configuring properties via XML

ceki ceki at qos.ch
Thu Nov 8 22:27:10 CET 2012

Have you looked at SiftingAppender [1]? If you can set an MDC variable 
at the beginning of a request served by each child app, the results 
should be rather close to what you are aiming. Give it a try.

[1] http://logback.qos.ch/manual/appenders.html#SiftingAppender

On 08.11.2012 19:54, Adam Gordon wrote:
> Ok, I really should have thought about what I really needed before posting.
> We have a "parent" GWT web application and we have children applications
> that are plugged into it.  The children can run as standalone web
> applications but this is really only for development.  Since each child
> can run independently, each has its own logback.xml file.
> Unfortunately, when the parent is built, the children are just JAR file
> dependencies and the parent also has it's own logback.xml file.
> Using only the parent's logback.xml file, we can configure different
> appenders (and thus different log files) for each of the children, but
> this only works because of the child namespacing (the Java package
> name).  The parent's logback.xml defines the root logger to use the
> parent's appender.  What this means is that if the children are using a
> common framework, say Spring, all the Spring logging doesn't go into the
> correct child's logfile, but rather the parent's.
> What we need is a way to either allow each child it's own, completely
> separate logging configuration or we need to "tag" the logging statement
> in the parent's log file with some name that indicates which child the
> message came from.
> I was looking at the concept of a context selector, but it wasn't clear
> how I'd be able to configure this to return the correct LoggingContext
> depending on which child issued the logging statement.
> Alternatively, I suppose I could add a filter which "sets" the current
> logging context based on the request URI - the children's request URIs
> are also namespaced so that each child's request URI always starts with
> /child_name/...
> Was this clear?  Do anyone have any thoughts on how best to approach
> this problem?
> Thanks,
> --adam
> http://gordonizer.com
> On Thu, Nov 8, 2012 at 11:01 AM, ceki <ceki at qos.ch <mailto:ceki at qos.ch>>
> wrote:
>     Please see [1] in the docs. For your use case, you need to define
>     the property in the context scope [2].
>     [1]
>     http://logback.qos.ch/manual/__configuration.html#__variableSubstitution
>     <http://logback.qos.ch/manual/configuration.html#variableSubstitution>
>     [2] http://logback.qos.ch/manual/__configuration.html#scopes
>     <http://logback.qos.ch/manual/configuration.html#scopes>
>     On 08.11.2012 18:54, Adam Gordon wrote:
>         The Layout chapter indicates it supports property value
>         retrieval via
>         %property{key} and states that the logging context is where one
>         might
>         put a property (along w/ System properties).  I believe log4j
>         did this
>         w/ the <param name="key_name" value="some_value"> element in the
>         <appender> and referenced it via %properties{key_name}.
>         I'm not seeing how to do this in Logback in XML. Would it go in the
>         <logger> element?  What's the syntax?  Could someone please
>         point me to
>         the relevant section in the appropriate chapter of the manual?
>         Thanks,
>         --adam

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