Coming in Karaf 3.0: new KAR service, command, management

December 27, 2011 Posted by jbonofre

We are working hard on Karaf 3.0. This major new version of Karaf will bring a lot of new features and enhancements.

KAR in Karaf 2.2.4

As you may know, Karaf 2.2.x already provides “basic” KAR support.

A KAR (KARaf archive) is a zip file which gathers a features XML and all bundles and configuration files dependencies. It means that a KAR is an atomic artifact which can be deployed without an Internet connection (as all is shipped in the KAR file itself).

In Karaf 2.2.x, the KAR support was:

  • a KAR deployer: you can copy a KAR file into the deploy folder, and KARAF will uncompress the KAR file, and install all features containing in the shipped features XML.
  • a create-kar goal in the features-maven-plugin: this goal reads a features XML and creates a KAR file, ready to be deployed.

So, all KAR logics were in the KAR deployer.

It means that you are not able to deploy a KAR from a remote URL, etc.

What’s coming in Karaf 3.0

The KAR service

In Karaf 3.0, the KAR core bundle provides a org.apache.karaf.kar.KarService OSGi service.

This service allows you to list the installed KAR files, deploy a KAR file from an URL, uninstall a KAR file.

Now the KAR service use a data/kar directory to store the KAR file and uncompress the KAR directly in the system repository (the local-repo directory is no more needed and created).

The KAR shell commands

Now, you have a complete control on the KAR files (including remotely using a SSH connection).

You can list, install, and uninstall KAR files using the kar:* commands:

  • kar:list displays the installed KAR files
  • kar:install installs a KAR file from a given URL. The URL could be a “classic” file: or http:, but, as for all stuff in Karaf, mvn: (for instance mvn:net.nanthrax/test/1.0-SNAPSHOT/kar)
  • kar:uninstall uninstalls a KAR file (identified by the name as displayed by kar:list). This command doesn’t alter the system repository by default, but you have an option -c (–cleanup) to cleanup the system repository.

The KAR MBean

You can also manipulate KAR files using JMX via a new MBean: org.apache.karaf:type=kar,name=root.

This MBean provides quite the same actions that you can do using the commands:

  • getKars()
  • install(url)
  • uninstall(name)
  • uninstall(name, clean)

In progress

It’s still a work in progress. I will add a bunch of unit tests and new features around the KAR files.

About jbonofre

ASF Member, PMC for Apache Karaf, PMC for Apache ServiceMix, PMC for Apache ACE, PMC for Apache Syncope, Committer for Apache ActiveMQ, Committer for Apache Archiva, Committer for Apache Camel, Contributor for Apache Falcon Twitter: jbonofre IRC: jbonofre on #servicemix,#karaf,#camel,#cxf on Freenode

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