1. Quick Start

If you are in a hurry to have Apache Karaf up and running right away, this section will provide you with some basic steps for downloading, building (when needed) and running the server in no time. This is clearly not a complete guide so you may want to check other sections of this guide for further information.

All you need is 5 to 10 minutes and to follow these basic steps.

Background

Apache Karaf is a small and lightweight OSGi based runtime. This provides a small lightweight container onto which various bundles can be deployed.

Apache Karaf started life as the Apache ServiceMix kernel and then moved as a Apache Felix subproject before becoming a top level project.

Getting the software

At this time you have one option to get the software. The fastest and easiest way is to get the binary directly from the Apache site. Since this article is intended to help you to have Apache Karaf up and running in the fastest way only the binary download will be covered at this time.

Prerequisites

Although this installation path is the fastest one, you will still need to install some software before installing Karaf.

Karaf requires a Java SE 5 environment to run. Refer to http://www.oracle.com/technetwork/java/javase/ for details on how to download and install Java SE 1.5 or greater.

Download binaries

You will need to select the appropriate installation image for the platform you're using to run Karaf. Open a Web browser and access the following URL, there you will find the available packages for download (binaries and source code).

http://karaf.apache.org/index/community/download.html

Select the file compression format compatible with your system (zip for windows, tar.gz for unixes) by clicking directly on the link, download it and expand the binary to your hard drive in a new directory; for example in z:\karaf - from now on this directory will be referenced as <KARAF_HOME>. Please remember the restrictions concerning illegal characters in Java paths, e.g. !, % etc.

The installation of Karaf is as simple as uncompressing the .zip or .tar.gz files. The next step is to start the server.

Start the server

With Karaf already installed, open a command line console and change directory to <KARAF_HOME>. To start the server, run the following command in Windows:

bin\karaf.bat

respectively on Unix:

bin/karaf

You should see the following information on the command line console:

You can now run your first command. Simply type the <tab> key in the console.

karaf@root> 

admin:change-port         admin:connect             admin:create              admin:destroy
admin:list                admin:start               admin:stop                config:cancel
config:edit               config:list               config:propappend         config:propdel
config:proplist           config:propset            config:update             dev:dynamic-import
dev:framework             dev:print-stack-traces    dev:show-tree             features:addUrl
features:info             features:install          features:list             features:listUrl
features:refreshUrl       features:removeUrl        features:uninstall        log:display
log:display-exception     log:get                   log:set                   osgi:bundle-level
osgi:headers              osgi:install              osgi:list                 osgi:ls
osgi:refresh              osgi:resolve              osgi:restart              osgi:shutdown
osgi:start                osgi:start-level          osgi:stop                 osgi:uninstall
osgi:update               packages:exports          packages:imports          shell:cat
shell:clear               shell:each                shell:echo                shell:exec
shell:grep                shell:history             shell:if                  shell:info
shell:java                shell:logout              shell:new                 shell:printf
shell:sleep               shell:sort                shell:tac                 ssh:ssh
ssh:sshd                  cat                       clear                     each
echo                      exec                      grep                      history
if                        info                      java                      logout
new                       printf                    sleep                     sort
tac                       bundle-level              headers                   install
list                      ls                        refresh                   resolve
restart                   shutdown                  start                     start-level
stop                      uninstall                 update
karaf@root> 

You can then grab more specific help for a given command using the --help option for this command:

karaf@root> admin:create --help
DESCRIPTION
	admin:create

	Create a new instance.

SYNTAX
	admin:create [options] name

ARGUMENTS
        name
                The name of the new container instance

OPTIONS
        --help
                Display this help message
        -f, --feature
                Initial features. This option can be specified multiple times to enable multiple initial 
                features
        -p, --port
                Port number for remote shell connection
        -l, --location
                Location of the new container instance in the file system
        -furl, --featureURL
                Additional feature descriptor URLs. This option can be specified multiple times to add 
                multiple URLs

karaf@root> 

Note that the console supports tab completion, so you just need to enter ad <tab> cr <tab> instead of admin:create.

Deploy a sample application

While you will learn in the Karaf user's guide how to fully use and leverage Apache Karaf, let's install a sample Apache Camel application for now:

In the console, run the following commands:

features:addurl mvn:org.apache.camel/camel-example-osgi/2.10.0/xml/features
features:install camel-example-osgi

The example installed is using Camel to start a timer every 2 seconds and output a message on the console.
The previous commands download the Camel features descriptor and install the example feature.

>>>> SpringDSL set body:  Fri Jan 07 11:59:51 CET 2011
>>>> SpringDSL set body:  Fri Jan 07 11:59:53 CET 2011
>>>> SpringDSL set body:  Fri Jan 07 11:59:55 CET 2011

Stopping and uninstalling the sample application

To stop this demo, run the following command:

features:uninstall camel-example-osgi

Common Problems

  1. Launching Karaf can result in a deadlock in Felix during module dependency resolution.

    This is often a result of sending a SIGINT (control-C) to the process when it will not cleanly exit.
    This can corrupt the caches and cause startup problems in the very next launch. It is fixed by emptying the component cache:

    rm -rf data/cache/*
    

Stopping Karaf

To stop Karaf from the console, enter ^D in the console:

^D

Alternatively, you can also run the following command:

osgi:shutdown

Summary

This document showed how simple it is to have Apache Karaf up and running. The overall time for getting the server running should be less than five
minutes if you have the prerequisite (Java 1.5) already installed. Additionally, this article also showed you how to deploy and test a simple
Apache Camel application.