KAR

As described in the Provisioning section, Apache Karaf features describe applications.

A feature defines different resources to resolve using URL (for instance, bundles URLs, or configuration files URLs). As described in the [Artifacts repositories and URLs section|urls], Apache Karaf looks for artifacts (bundles, configuration files, …) in the artifact repositories. Apache Karaf may require to download artifacts from remote repositories.

Apache Karaf provides a special type of artifact that package a features XML and all resources described in the features of this XML. This artifact is named a KAR (KAraf aRchive).

A KAR file is a zip archive containing the

Basically, the kar format is a jar (so a zip file) which contains a set of feature descriptor and bundle jar files.

A KAR file contains a repository folder containing:

a set of features XML files
the artifacts following the Maven directory structure (groupId/artifactId/version/artifactId-version.type).

For instance, the spring-3.0.0.kar contains:

~$ unzip -l spring-3.0.0.kar
Archive:  spring-3.0.0.kar
  Length      Date    Time    Name
---------  ---------- -----   ----
      143  2013-12-06 10:52   META-INF/MANIFEST.MF
    12186  2013-12-06 10:52   repository/org/apache/karaf/features/spring/3.0.0/spring-3.0.0-features.xml
   575389  2013-12-06 10:52   repository/commons-collections/commons-collections/3.2.1/commons-collections-3.2.1.jar
   232019  2013-12-06 10:52   repository/commons-beanutils/commons-beanutils/1.8.3/commons-beanutils-1.8.3.jar
   673109  2013-12-06 10:52   repository/org/apache/servicemix/bundles/org.apache.servicemix.bundles.struts/1.3.10_1/org.apache.servicemix.bundles.struts-1.3.10_1.jar
    37084  2013-12-06 10:52   repository/org/springframework/org.springframework.web.struts/3.2.4.RELEASE/org.springframework.web.struts-3.2.4.RELEASE.jar
     7411  2013-12-06 10:52   repository/org/springframework/org.springframework.instrument/3.2.4.RELEASE/org.springframework.instrument-3.2.4.RELEASE.jar
   246881  2013-12-06 10:52   repository/org/springframework/org.springframework.transaction/3.2.4.RELEASE/org.springframework.transaction-3.2.4.RELEASE.jar
    16513  2013-12-06 10:52   repository/org/apache/servicemix/bundles/org.apache.servicemix.bundles.aopalliance/1.0_6/org.apache.servicemix.bundles.aopalliance-1.0_6.jar
   881124  2013-12-06 10:52   repository/org/springframework/org.springframework.core/3.2.4.RELEASE/org.springframework.core-3.2.4.RELEASE.jar
   199240  2013-12-06 10:52   repository/org/springframework/org.springframework.expression/3.2.4.RELEASE/org.springframework.expression-3.2.4.RELEASE.jar
   614646  2013-12-06 10:52   repository/org/springframework/org.springframework.beans/3.2.4.RELEASE/org.springframework.beans-3.2.4.RELEASE.jar
   340841  2013-12-06 10:52   repository/org/springframework/org.springframework.aop/3.2.4.RELEASE/org.springframework.aop-3.2.4.RELEASE.jar
   877369  2013-12-06 10:52   repository/org/springframework/org.springframework.context/3.2.4.RELEASE/org.springframework.context-3.2.4.RELEASE.jar
   130224  2013-12-06 10:52   repository/org/springframework/org.springframework.context.support/3.2.4.RELEASE/org.springframework.context.support-3.2.4.RELEASE.jar
    30640  2013-12-06 10:52   repository/org/apache/karaf/deployer/org.apache.karaf.deployer.spring/3.0.0/org.apache.karaf.deployer.spring-3.0.0.jar
    51951  2013-12-06 10:52   repository/org/springframework/org.springframework.aspects/3.2.4.RELEASE/org.springframework.aspects-3.2.4.RELEASE.jar
   411175  2013-12-06 10:52   repository/org/springframework/org.springframework.jdbc/3.2.4.RELEASE/org.springframework.jdbc-3.2.4.RELEASE.jar
    48049  2013-12-06 10:52   repository/javax/portlet/portlet-api/2.0/portlet-api-2.0.jar
   190883  2013-12-06 10:52   repository/org/springframework/org.springframework.web.portlet/3.2.4.RELEASE/org.springframework.web.portlet-3.2.4.RELEASE.jar
   635680  2013-12-06 10:52   repository/org/springframework/org.springframework.web/3.2.4.RELEASE/org.springframework.web-3.2.4.RELEASE.jar
   645946  2013-12-06 10:52   repository/org/springframework/org.springframework.web.servlet/3.2.4.RELEASE/org.springframework.web.servlet-3.2.4.RELEASE.jar
   464911  2013-12-06 10:52   repository/org/springframework/org.springframework.test/3.2.4.RELEASE/org.springframework.test-3.2.4.RELEASE.jar
    69784  2013-12-06 10:52   repository/org/springframework/osgi/spring-osgi-web/1.2.1/spring-osgi-web-1.2.1.jar
    16030  2013-12-06 10:52   repository/org/apache/geronimo/specs/geronimo-jta_1.1_spec/1.1.1/geronimo-jta_1.1_spec-1.1.1.jar
    32359  2013-12-06 10:52   repository/org/apache/geronimo/specs/geronimo-jms_1.1_spec/1.1.1/geronimo-jms_1.1_spec-1.1.1.jar
   208684  2013-12-06 10:52   repository/org/springframework/org.springframework.jms/3.2.4.RELEASE/org.springframework.jms-3.2.4.RELEASE.jar
    75672  2013-12-06 10:52   repository/org/springframework/org.springframework.oxm/3.2.4.RELEASE/org.springframework.oxm-3.2.4.RELEASE.jar
   393607  2013-12-06 10:52   repository/org/springframework/org.springframework.orm/3.2.4.RELEASE/org.springframework.orm-3.2.4.RELEASE.jar
   338559  2013-12-06 10:52   repository/org/apache/servicemix/bundles/org.apache.servicemix.bundles.cglib/3.0_1/org.apache.servicemix.bundles.cglib-3.0_1.jar
    35859  2013-12-06 10:52   repository/org/springframework/osgi/spring-osgi-io/1.2.1/spring-osgi-io-1.2.1.jar
   362889  2013-12-06 10:52   repository/org/springframework/osgi/spring-osgi-core/1.2.1/spring-osgi-core-1.2.1.jar
   120822  2013-12-06 10:52   repository/org/springframework/osgi/spring-osgi-extender/1.2.1/spring-osgi-extender-1.2.1.jar
    24231  2013-12-06 10:52   repository/org/springframework/osgi/spring-osgi-annotation/1.2.1/spring-osgi-annotation-1.2.1.jar
    12597  2013-12-06 10:52   repository/org/apache/karaf/bundle/org.apache.karaf.bundle.springstate/3.0.0/org.apache.karaf.bundle.springstate-3.0.0.jar
    31903  2013-12-06 10:52   repository/org/eclipse/gemini/blueprint/gemini-blueprint-io/1.0.0.RELEASE/gemini-blueprint-io-1.0.0.RELEASE.jar
   578205  2013-12-06 10:52   repository/org/eclipse/gemini/blueprint/gemini-blueprint-core/1.0.0.RELEASE/gemini-blueprint-core-1.0.0.RELEASE.jar
   178525  2013-12-06 10:52   repository/org/eclipse/gemini/blueprint/gemini-blueprint-extender/1.0.0.RELEASE/gemini-blueprint-extender-1.0.0.RELEASE.jar
---------                     -------
  9803140                     38 files

As a KAR file is a simple zip file, you can create the KAR file by hand.

For instance, the following Unix commands create a very simple KAR file:

~$ mkdir repository
~$ cp /path/to/features.xml repository/features.xml
~$ cp /path/to/my.jar repository/my/project/my/1.0.0/my-1.0.0.jar
~$ zip -r my.kar repository
updating: repository/ (stored 0%)
  adding: repository/my/project/my/1.0.0/my-1.0.0.jar (deflated 0%)

You can create KAR files using Apache Maven, or directly in the Apache Karaf console.

Maven

Apache Karaf provides a Maven plugin: karaf-maven-plugin.

The Apache Karaf Maven plugin provides the features-create-kar goal.

The features-create-kar goal does:

Reads all features specified in the features XML.
For each feature described in the features XML, the goal resolves the bundles described in the feature.
The goal finally packages the features XML, and the resolved bundles in a zip file.

You can also use the Karaf maven plugin. The features maven plugin provides an features-create-kar goal.

The features-create-kar goal:

Reads all features specified in the features descriptor.
For each feature, it resolves the bundles defined in the feature.
All bundles are packaged into the kar archive.

For instance, the following Maven POM create my-kar.kar

For instance, you can use the following POM to create a kar:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>my.groupId</groupId>
    <artifactId>my-kar</artifactId>
    <version>1.0</version>
    <packaging>pom</packaging>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.karaf.tooling</groupId>
                <artifactId>karaf-maven-plugin</artifactId>
                <version>3.0.0</version>
                <executions>
                    <execution>
                        <id>features-create-kar</id>
                        <goals>
                            <goal>features-create-kar</goal>
                        </goals>
                        <configuration>
                            <featuresFile>src/main/resources/features.xml</featuresFile>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

To create the KAR file, simply type:

~$ mvn install

Uou will have your kar in the target directory.

Commands

Apache Karaf provides kar:* commands to manage KAR archives.

`kar:list`

The kar:list command lists the installed KAR archives.

karaf@root()> kar:list
KAR Name
-------------------
my-kar-1.0-SNAPSHOT

A KAR is identified by its name.

`kar:create`

Instead of using the karaf-maven-plugin or create the KAR archive by hand, you can use the kar:create command.

The kar:create command creates a KAR file using a registered features repository.

For instance, you want to create a KAR file for the Pax Web repository.

The feature:repo-list command gives you the list of registered features repositories:

karaf@root()> feature:repo-list
Repository                       | URL
-------------------------------------------------------------------------------------------------------
standard-3.0.0                   | mvn:org.apache.karaf.features/standard/3.0.0/xml/features
enterprise-3.0.0                 | mvn:org.apache.karaf.features/enterprise/3.0.0/xml/features
spring-3.0.0                     | mvn:org.apache.karaf.features/spring/3.0.0/xml/features
org.ops4j.pax.web-3.0.5          | mvn:org.ops4j.pax.web/pax-web-features/3.0.5/xml/features

You can use one of these features repositories to create the kar file:

karaf@root()> kar:create org.ops4j.pax.web-3.0.5
Adding feature pax-war
Adding feature pax-http-whiteboard
Adding feature pax-jetty
Adding feature pax-tomcat
Adding feature pax-http
Kar file created : /opt/apache-karaf-3.0.0/data/kar/org.ops4j.pax.web-3.0.5.kar

You can see that the KAR file has been created in the KARAF_DATA/kar folder.

By default, the kar:create command creates a KAR file, packaging all features in the features descriptor.

You can provide the list of features that you want to package into the KAR file:

karaf@root()> kar:create org.ops4j.pax.web-3.0.5 pax-jetty pax-tomcat
Adding feature pax-jetty
Adding feature pax-tomcat
Kar file created : /opt/apache-karaf-3.0.0/data/kar/org.ops4j.pax.web-3.0.5.kar

`kar:install`

You can deploy a KAR file using kar:install command.

The kar:install command expects the KAR URL. Any URL described in the [Artifacts repositories and URLs section|urls] is supported by the kar:install command:

karaf@root()> kar:install file:/tmp/my-kar-1.0-SNAPSHOT.kar

The KAR file is uncompressed and populated the KARAF_BASE/system folder.

The Apache Karaf KAR service is looking for features XML files in the KAR file, registers the features XML and automatically installs all features described in the features repositories present in the KAR file.

`kar:uninstall`

The kar:uninstall command uninstall a KAR file (identified by a name).

By uninstall, it means that:

the features previously installed by the KAR file are uninstalled
delete (from the KARAF_DATA/system repository) all files previously "populated" by the KAR file

For instance, to uninstall the previously installed my-kar-1.0-SNAPSHOT.kar KAR file:

karaf@root()> kar:uninstall my-kar-1.0-SNAPSHOT

Deployer

Apache Karaf also provides a KAR deployer. It means that you can drop a KAR file directly in the deploy folder.

Apache Karaf will automatically install KAR files from the deploy folder.

You can change the behaviours of the KAR deployer in the etc/org.apache.karaf.kar.cfg:

################################################################################
#
#    Licensed to the Apache Software Foundation (ASF) under one or more
#    contributor license agreements.  See the NOTICE file distributed with
#    this work for additional information regarding copyright ownership.
#    The ASF licenses this file to You under the Apache License, Version 2.0
#    (the "License"); you may not use this file except in compliance with
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#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#    See the License for the specific language governing permissions and
#    limitations under the License.
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#
# Enable or disable the refresh of the bundles when installing
# the features contained in a KAR file
#
noAutoRefreshBundles=false

By default, when the KAR deployer install features, by default, it refresh the bundles already installed. You can disable the automatic bundles refresh by setting the noAutoRefreshBundles property to false.

JMX KarMBean

On the JMX layer, you have a MBean dedicated to the management of the KAR files.

The ObjectName to use is org.apache.karaf:type=kar,name=*.

Attributes

The Kars attributes provides the list of KAR files (name) installed.

Operations

install(url) installs the KAR file at the given url.
create(repository, features) creates a KAR file using the given features repository name, and optionally the list of features to include in the KAR file.
uninstall(name) uninstalls a KAR file with the given name.