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https://jira.codehaus.org/browse/MNG-5510?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Juan Pablo Santos RodrÃguez reopened MNG-5510:
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Hi Jason,
let me reopen the issue, as it seems to me it has been misunderstood. The issue
is triggered because of having speficic requirements coded against specific
SLF4J implementations (btw, f.ex., if you try to reload the log's config file
you'll have to go against your specific SLF4J implementation), but it's only an
example, as the issue has a broader scope.
We've already made the appropiate changes to bypass the affected code if not on
Logback and carried on, but it was just an example of Maven leaking its SLF4J
implementation. We had problems with the tomcat and jetty maven plugins when
using a different SLF4J implementation, because of having two different SLF4J
implementations on classpath.
Another example: go to {{$MAVEN_HOME/lib}} and change the simple-slf4j jars
with another SLF4J implementation. Just because you want to colour maven
output, or you want your logs on a database or whatever strange reason you may
come up to. As noted at the bottom of \[#1], it's fairly trivial.
Then, when doing a {{mvn sonar:sonar}} on any maven project, you'll get
something like:
{code}
08:26:09.204 [main] ERROR org.apache.maven.cli.MavenCli Failed to execute goal
org.codehaus.mojo:sonar-maven-plugin:2.3:sonar (default-cli) on project
YOUR_PROJECT_HERE: Error setting Log implementation. Cause:
java.lang.reflect.InvocationTargetException: org/slf4j/Marker -> [Help 1]
08:26:09.204 [main] ERROR org.apache.maven.cli.MavenCli
{code}
Forking a new VM may not always be an option, and there may be justified cases
which enforce the use of an specific slf4j implementation, leading to this
issue. I'm attaching a simple project to reproduce the issue.
\[#1] http://maven.apache.org/maven-logging.html
> Maven causing ClassCastException with container plugins when project is using
> other SLF4J implementation than slf4j-simple
> --------------------------------------------------------------------------------------------------------------------------
>
> Key: MNG-5510
> URL: https://jira.codehaus.org/browse/MNG-5510
> Project: Maven 2 & 3
> Issue Type: Bug
> Components: Bootstrap & Build, Logging
> Affects Versions: 3.1.0
> Reporter: Juan Pablo Santos RodrÃguez
> Attachments: MNG-5510-sample.zip
>
>
> On our project we're using directly logback to start up a custom mbean to be
> able to change log levels dynamically, among other things. Most of these
> operations are Logback-specific, they're not available via SLF4J API
> For testing we use Jetty, so when we're doing an mvn jetty:run, the mbean
> gets init'd and we get an Exception stating "ClassCastException:
> org.slf4j.impl.SimpleLoggerFactory cannot be cast to
> ch.qos.logback.classic.LoggerContext", due to slf4j-simple being on maven's
> lib. This is very likely to happen with other container plugins (tomcat7 et
> al)
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