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

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.

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