In the process of trying to learn about Apache Karaf I put together a set of skeleton projects (based on Karaf 2.2.4) that help to bootstrap a custom distribution. The end goal is a standalone Karaf installation that includes your application bundle(s) in a standalone archive that can be deployed to a Maven-less, Internet-less machine. Your custom deployment is wrapped up in a single ZIP file with all dependencies embedded.

There's nothing new here, just a distillation of docs, mailing list threads, Maven wrangling and the like. You're still need to going to write your application.

The sub-projects are:

• com.custom.branding : Resource-only bundle that customizes the Karaf console shell per the instructions.
• com.custom.karafbundle : Simple Java OSGi bundle with the obligatory Hello World
• com.custom.karafhost : The "host" installation. A Karaf installation, including both OSX and Windows shell scripts, will be downloaded and pre-populated with the custom set of bundles. Eclipse Run Configurations that delegate to the downloaded platform shell scripts are included as external files in the project.
• com.custom.karafservlet : PAX Whiteboard registered servlet at "/hello" which outputs, unoriginally, Hello World.
• com.custom.scalabundle : Scala implementation of simple Hello World OSGi bundle.

• Maven 3.x

For Eclipse Building:

• Eclipse
• M2Eclipse

For Scala integration:

• Scala IDE for Eclipse (Optional)

1. From a command prompt in the com.custom.karafhost directory, enter "mvn install"
2. Navigate to the .../com.custom.karafhost/target/karaf/apache-karaf-2.2.4/bin directory and launch your platform-specific karaf.* shell script.

1. From the com.custom.karafhost project context menu, select Run As -> Maven Install
2. Assuming all goes well, you should see something like:

[INFO] Custom :: Karaf :: Java Bundle .................... SUCCESS [1.988s]
[INFO] Custom :: Karaf :: Scala Bundle ................... SUCCESS [2.935s]
[INFO] Custom :: Karaf :: Java Servlet ................... SUCCESS [0.525s]
[INFO] Custom :: Karaf :: Console Branding ............... SUCCESS [0.459s]
[INFO] Custom :: Karaf :: Distribution ................... SUCCESS [12.737s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 19.324s
[INFO] Finished at: Mon Dec 26 15:39:57 PST 2011
[INFO] Final Memory: 15M/123M
[INFO] ------------------------------------------------------------------------

In the com.custom.karafhost project, disclose the run_configurations folder and select the appropriate - Run.launch target to start the Karaf session.

Once Karaf has started up, you can enter the Eclipse Console to interact with the running instance. For instance, features:list will list the available features and their installation state. Assuming everything built, the tail of the features:list should include:

…SNIP…
[installed  ] [0.0.1-SNAPSHOT ] karafbundle                   repo-0                 
[installed  ] [0.0.1-SNAPSHOT ] scalabundle                   repo-0                 
[installed  ] [0.0.1-SNAPSHOT ] karafservlet                  repo-0      

You can also interact with the included WebConsole by visiting the page at http://localhost:8080/system/console. Login using:

• user: karaf
• password: karaf

The HTTP port is configurable in the .../com.custom.karafhost/src/main/resources/karaf/etc/org.ops4j.pax.web.cfg file's org.osgi.service.http.port property.

To shutdown the Karaf instance, enter the shutdown command in the console.

Karaf introduces a packaging abstraction called a Feature. Features are collections of JARs that represent a single application-level set of functionality. The bundles in this repo include the following feature mappings:

• karafbundle -> com.custom.karafbundle
• karafservlet -> com.custom.karafservlet
• scalabundle -> com.custom.scalabundle

The feature mappings are defined in .../com.custom.karafhost/src/main/resources/karaf/system/features.xml

To add your custom feature bundle:

1. Create a new project
2. Add the new project to the modules section in .../chiller/com.custom.karafhost/pom.xml
3. Add the feature group to the .../com.custom.karafhost/src/main/resources/karaf/system/features.xml file. This is where you will define the feature-name, which is used in the next two steps.
4. In the add-local-features-to-repo execution id in .../chiller/com.custom.karafhost/pom.xml, include your new feature-name in the list of features to include in the distribution. If you don't deploy your feature-name to the local-repo, it won't be available at runtime.
5. If you would like your feature to launch at startup, in .../com.custom.karafhost/src/main/resources/karaf/etc/org.apache.karaf.features.cfg, add your new feature-name to the comma-separated featuresBoot property. Note that specifying a non-existent feature-name to launch at boot time doesn't seem to generate an error.
6. Clean and rebuild the parent com.custom.karafhost project. Once the build is launched, use the features:list command to verify that your custom feature is both deployed and installed.

• I'm not sure how to brand the Karaf WebConsole. I tried the Felix approach, but was unsuccessful.
• This was primarily a learning experience for Karaf, so I'd appreciate any corrections or improvements.