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javaloggingosgiapache-felixlog4j2

Using Log4j2 from an embedded OSGi framework

We are usingApache Felix (version 4.4.1)as an embedded OSGi framework. The main application that is providing the framework is usingLog4j2 (version 2.0.1)as logging framework. There are dependencies on log4j-api and log4j-core. Of course when the main application is started also Log4j2 will be loaded and configured. All log messages triggered in the main part are correctly written to the configured appenders.

Now the point. All bundles that are loaded should be able using the same configuration and for that the same LoggingContext as the main application. What I was trying to do is providing all Log4j2 packages (from log4j2-api and log4j-core) by putting them into the framework configuration asorg.osgi.framework.system.packages.extra. But when the bundles are loaded the log4j2 packages do not appear in the list of wiring packages as other provided packages do and when a bundle class tries to access Log4j2 classes an exception will be thrown.

All bundles are configured the same way and having Log4j2 dependencies on log4j2-api and log4j2-core with scope provided. When I'm looking into the MANIFEST.MF the used Log4j2 packages are within theImport-Packagespart

So my questions are.

Why exporting of Log4j2 packages this way does not work? How do I have to configure my environment so I can use same LoggingContext in my bundles and main application?

Here is my configuration part of the OSGi framework from the java code:

Map<String, String> temp = new HashMap<String, String>();
// setting parameter that the felix cache is new initialized on each
// start of the application
temp.put(org.osgi.framework.Constants.FRAMEWORK_STORAGE_CLEAN, "onFirstInit");
// setting the packages that are provided by the main system and can
// be used by the osgi bundles
temp.put(org.osgi.framework.Constants.FRAMEWORK_SYSTEMPACKAGES_EXTRA,
// have to export these explicitly as the automatic export does
// not work for this internal java packages
+ "com.sun.org.apache.xerces.internal.dom,"
+ "com.sun.org.apache.xerces.internal.jaxp,"
+ "com.sun.org.apache.xerces.internal.util,"
// export the looging packages
+ "org.apache.log4j," + "org.apache.logging.log4j," +   "org.apache.logging.log4j.message,"
+ "org.apache.logging.log4j.simple," + "org.apache.logging.log4j.spi,"
+ "org.apache.logging.log4j.status," + "org.apache.logging.log4j.util,"
+ "org.apache.logging.log4j.impl," + "org.apache.logging.log4j.appender,"
+ "org.apache.logging.log4j.appender.db," + "org.apache.logging.log4j.appender.db.jdbc,"
+ "org.apache.logging.log4j.appender.db.jpa," + "org.apache.logging.log4j.appender.db.jpa.converter,"
+ "org.apache.logging.log4j.appender.jms," + "org.apache.logging.log4j.appender.rewrite,"
+ "org.apache.logging.log4j.appender.rolling," + "org.apache.logging.log4j.appender.rolling.action,"
+ "org.apache.logging.log4j.appender.routing," + "org.apache.logging.log4j.async,"
+ "org.apache.logging.log4j.config," + "org.apache.logging.log4j.config.json,"
+ "org.apache.logging.log4j.config.plugins," + "org.apache.logging.log4j.config.plugins.osgi,"
+ "org.apache.logging.log4j.config.plugins.processor,"
+ "org.apache.logging.log4j.config.plugins.util," + "org.apache.logging.log4j.config.plugins.visitors,"
+ "org.apache.logging.log4j.config.status," + "org.apache.logging.log4j.config.xml,"
+ "org.apache.logging.log4j.config.yaml," + "org.apache.logging.log4j.filter,"
+ "org.apache.logging.log4j.impl," + "org.apache.logging.log4j.jackson,"
+ "org.apache.logging.log4j.jmx," + "org.apache.logging.log4j.layout,"
+ "org.apache.logging.log4j.lookup," + "org.apache.logging.log4j," + "org.apache.logging.log4j.net,"
+ "org.apache.logging.log4j.net.jms," + "org.apache.logging.log4j.net.server,"
+ "org.apache.logging.log4j.net.ssl," + "org.apache.logging.log4j.pattern,"
+ "org.apache.logging.log4j.selector," + "org.apache.logging.log4j.tools,"
+ "org.apache.logging.log4j.util," + "sun.misc," + "javax.jms," + "javax.mail,"
+ "javax.mail.internet," + "javax.mail.util," + "javax.persistence," + "javax.servlet,"
+ "com.sun.xml.internal.bind");
temp.put(FelixConstants.LOG_LEVEL_PROP, "4");
OSGI_CONFIG = Collections.unmodifiableMap(temp);

Dependencies on log4j2 libs in bundles are defined as followos:

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.0.1</version>
    <scope>provided</scope>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-api</artifactId>
    <version>2.0.1</version>
    <scope>provided</scope>
</dependency>
Solution

  • We have found a solution, that works for us with version 2.0.1. Instead of setting the needed log4j packages in theImport-Packagepart of the MANIFEST.MF we have added them to theDynamicImport-Packagedefinition. After that the classes are dynamically wired when needed and all OSGi bundles can use the same LoggerContext.