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Chapter 15. Introduction to the Deploying into Apache Karaf user guide
Abstract
Before you use this User Guide section of the Deploying into Apache Karaf guide, you must have installed the latest version of Red Hat Fuse, following the instructions in Installing on Apache Karaf.
15.1. Introducing Fuse Configuration
The OSGi Configuration Admin service specifies the configuration information for deployed services and ensures that the services receive that data when they are active.
15.2. OSGi configuration
A configuration is a list of name-value pairs read from a .cfg
file in the FUSE_HOME/etc
directory. The file is interpreted using the Java properties file format. The filename is mapped to the persistent identifier (PID) of the service that is to be configured. In OSGi, a PID is used to identify a service across restarts of the container.
15.3. Configuration files
You can configure the Red Hat Fuse runtime using the following files:
Filename | Description |
---|---|
| The main configuration file for the container. |
| The main configuration file for custom properties for the container. |
|
Lists the users who can access the Fuse runtime using the SSH key-based protocol. The file’s contents take the format |
| The features repository URLs. |
| Configures a list of feature repositories to be registered and a list of features to be installed when Fuse starts up for the first time. |
| Configures options for the Karaf JAAS login module. Mainly used for configuring encrypted passwords (disabled by default). |
|
Configures the output of the |
| Configures the JMX system. |
| Configures the properties of remote consoles. |
| Configures the logging system. |
| Narayana transaction manager configuration |
| Configures additional URL resolvers. |
| Configures the default Undertow container (Web server). See Securing the Undertow HTTP Server in the Red Hat Fuse Apache CXF Security Guide. |
|
Specifies which bundles are started in the container and their start-levels. Entries take the format |
|
Specifies Java system properties. Any properties set in this file are available at runtime using |
|
Lists the users who can access the Fuse runtime either remotely or via the web console. The file’s contents take the format |
|
This file is in the |
15.4. Configuration file naming convention
The file naming convention for configuration files depends on whether the configuration is intended for an OSGi Managed Service or for an OSGi Managed Service factory.
The configuration file for an OSGi Managed Service obeys the following naming convention:
<PID>.cfg
Where <PID>
is the persistent ID of the OSGi Managed Service (as defined in the OSGi Configuration Admin specification). A persistent ID is normally dot-delimited—for example, org.ops4j.pax.web
.
The configuration file for an OSGi Managed Service Factory obeys the following naming convention:
<PID>-<InstanceID>.cfg
Where <PID>
is the persistent ID of the OSGi Managed Service Factory. In the case of a managed service factory’s <PID>,
you can append a hyphen followed by an arbitrary instance ID, <InstanceID>
. The managed service factory then creates a unique service instance for each <InstanceID>
that it finds.
15.5. Setting Java Options
Java Options can be set using the /bin/setenv
file in Linux, or the bin/setenv.bat
file for Windows. Use this file to directly set a group of Java options: JAVA_MIN_MEM, JAVA_MAX_MEM, JAVA_PERM_MEM, JAVA_MAX_PERM_MEM. Other Java options can be set using the EXTRA_JAVA_OPTS variable.
For example, to allocate minimum memory for the JVM use
JAVA_MIN_MEM=512M # Minimum memory for the JVM
To set a Java option other than the direct options, use
EXTRA_JAVA_OPTS="Java option"
For example,
EXTRA_JAVA_OPTS="-XX:+UseG1GC"
15.6. Config Console Commands
There are a number of console commands that can be used to change or interrogate the configuration of Fuse 7.3.
See the Config section in the Apache Karaf Console Reference for more details about the config: commands.
15.7. JMX ConfigMBean
On the JMX layer, the MBean is dedicated to configuration management.
The ConfigMBean
object name is: org.apache.karaf:type=config,name=*`
.
14.1.2.1. Attributes
The config MBean contains a list of all configuration PIDs.
14.1.2.2. Operations
Operation name | Description |
---|---|
| returns the list of properties (property=value formatted) for the configuration pid. |
| deletes the property from the configuration pid. |
| appends value at the end of the value of the property of the configuration pid. |
| sets value for the value of the property of the configuration pid. |
| deletes the configuration identified by the pid. |
| creates an empty (without any property) configuration with pid. |
| updates a configuration identified with pid with the provided properties map. |
15.8. Using the console
15.8.1. Available commands
To see a list of the available commands in the console, you can use the help
:
karaf@root()> help bundle Enter the subshell bundle:capabilities Displays OSGi capabilities of a given bundles. bundle:classes Displays a list of classes/resources contained in the bundle bundle:diag Displays diagnostic information why a bundle is not Active bundle:dynamic-import Enables/disables dynamic-import for a given bundle. bundle:find-class Locates a specified class in any deployed bundle bundle:headers Displays OSGi headers of a given bundles. bundle:id Gets the bundle ID. ...
You have the list of all commands with a short description.
You can use the tab key to get a quick list of all commands:
karaf@root()> Display all 294 possibilities? (y or n) ...
15.8.2. Subshell and completion mode
The commands have a scope and a name. For instance, the command feature:list
has feature
as scope, and list
as name.
Karaf "groups" the commands by scope. Each scope form a subshell.
You can directly execute a command with its full qualified name (scope:name):
karaf@root()> feature:list ...
or enter in a subshell and type the command contextual to the subshell:
karaf@root()> feature karaf@root(feature)> list
You can note that you enter in a subshell directly by typing the subshell name (here feature
). You can "switch" directly from a subshell to another:
karaf@root()> feature karaf@root(feature)> bundle karaf@root(bundle)>
The prompt displays the current subshell between ().
The exit
command goes to the parent subshell:
karaf@root()> feature karaf@root(feature)> exit karaf@root()>
The completion mode defines the behaviour of the tab key and the help command.
You have three different modes available:
- GLOBAL
- FIRST
- SUBSHELL
You can define your default completion mode using the completionMode property in etc/org.apache.karaf.shell.cfg
file. By default, you have:
completionMode = GLOBAL
You can also change the completion mode “on the fly” (while using the Karaf shell console) using the shell:completion
command:
karaf@root()> shell:completion GLOBAL karaf@root()> shell:completion FIRST karaf@root()> shell:completion FIRST
shell:completion
can inform you about the current completion mode used. You can also provide the new completion mode that you want.
GLOBAL completion mode is the default one in Karaf 4.0.0 (mostly for transition purpose).
GLOBAL mode doesn’t really use subshell: it’s the same behavior as in previous Karaf versions.
When you type the tab key, whatever in which subshell you are, the completion will display all commands and all aliases:
karaf@root()> <TAB> karaf@root()> Display all 273 possibilities? (y or n) ... karaf@root()> feature karaf@root(feature)> <TAB> karaf@root(feature)> Display all 273 possibilities? (y or n)
FIRST completion mode is an alternative to the GLOBAL completion mode.
If you type the tab key on the root level subshell, the completion will display the commands and the aliases from all subshells (as in GLOBAL mode). However, if you type the tab key when you are in a subshell, the completion will display only the commands of the current subshell:
karaf@root()> shell:completion FIRST karaf@root()> <TAB> karaf@root()> Display all 273 possibilities? (y or n) ... karaf@root()> feature karaf@root(feature)> <TAB> karaf@root(feature)> info install list repo-add repo-list repo-remove uninstall version-list karaf@root(feature)> exit karaf@root()> log karaf@root(log)> <TAB> karaf@root(log)> clear display exception-display get log set tail
SUBSHELL completion mode is the real subshell mode.
If you type the tab key on the root level, the completion displays the subshell commands (to go into a subshell), and the global aliases. Once you are in a subshell, if you type the TAB key, the completion displays the commands of the current subshell:
karaf@root()> shell:completion SUBSHELL karaf@root()> <TAB> karaf@root()> * bundle cl config dev feature help instance jaas kar la ld lde log log:list man package region service shell ssh system karaf@root()> bundle karaf@root(bundle)> <TAB> karaf@root(bundle)> capabilities classes diag dynamic-import find-class headers info install list refresh requirements resolve restart services start start-level stop uninstall update watch karaf@root(bundle)> exit karaf@root()> camel karaf@root(camel)> <TAB> karaf@root(camel)> backlog-tracer-dump backlog-tracer-info backlog-tracer-start backlog-tracer-stop context-info context-list context-start context-stop endpoint-list route-info route-list route-profile route-reset-stats route-resume route-show route-start route-stop route-suspend
15.8.3. Unix like environment
Karaf console provides a full Unix like environment.
15.8.3.1. Help or man
We already saw the usage of the help
command to display all commands available.
But you can also use the help
command to get details about a command or the man
command which is an alias to the help
command. You can also use another form to get the command help, by using the --help
option to the command.
So these commands
karaf@root()> help feature:list karaf@root()> man feature:list karaf@root()> feature:list --help
All produce the same help output:
DESCRIPTION feature:list Lists all existing features available from the defined repositories. SYNTAX feature:list [options] OPTIONS --help Display this help message -o, --ordered Display a list using alphabetical order -i, --installed Display a list of all installed features only --no-format Disable table rendered output
15.8.3.2. Completion
When you type the tab key, Karaf tries to complete:
- subshell
- commands
- aliases
- command arguments
- command options
15.8.3.3. Alias
An alias is another name associated to a given command.
The shell:alias
command creates a new alias. For instance, to create the list-installed-features
alias to the actual feature:list -i
command, you can do:
karaf@root()> alias "list-features-installed = { feature:list -i }" karaf@root()> list-features-installed Name | Version | Required | State | Repository | Description ------------------------------------------------------------------------------------------------------------------------------ feature | 4.0.0 | x | Started | standard-4.0.0 | Features Support shell | 4.0.0 | x | Started | standard-4.0.0 | Karaf Shell deployer | 4.0.0 | x | Started | standard-4.0.0 | Karaf Deployer bundle | 4.0.0 | x | Started | standard-4.0.0 | Provide Bundle support config | 4.0.0 | x | Started | standard-4.0.0 | Provide OSGi ConfigAdmin support diagnostic | 4.0.0 | x | Started | standard-4.0.0 | Provide Diagnostic support instance | 4.0.0 | x | Started | standard-4.0.0 | Provide Instance support jaas | 4.0.0 | x | Started | standard-4.0.0 | Provide JAAS support log | 4.0.0 | x | Started | standard-4.0.0 | Provide Log support package | 4.0.0 | x | Started | standard-4.0.0 | Package commands and mbeans service | 4.0.0 | x | Started | standard-4.0.0 | Provide Service support system | 4.0.0 | x | Started | standard-4.0.0 | Provide System support kar | 4.0.0 | x | Started | standard-4.0.0 | Provide KAR (KARaf archive) support ssh | 4.0.0 | x | Started | standard-4.0.0 | Provide a SSHd server on Karaf management | 4.0.0 | x | Started | standard-4.0.0 | Provide a JMX MBeanServer and a set of MBeans in
At login, the Apache Karaf console reads the etc/shell.init.script
file where you can create your aliases. It’s similar to a bashrc or profile file on Unix.
ld = { log:display $args } ; lde = { log:exception-display $args } ; la = { bundle:list -t 0 $args } ; ls = { service:list $args } ; cl = { config:list "(service.pid=$args)" } ; halt = { system:shutdown -h -f $args } ; help = { *:help $args | more } ; man = { help $args } ; log:list = { log:get ALL } ;
You can see here the aliases available by default:
-
ld
is a short form to display log (alias tolog:display
command) -
lde
is a short form to display exceptions (alias tolog:exception-display
command) -
la
is a short form to list all bundles (alias tobundle:list -t 0
command) -
ls
is a short form to list all services (alias toservice:list
command) -
cl
is a short form to list all configurations (alias toconfig:list
command) -
halt
is a short form to shutdown Apache Karaf (alias tosystem:shutdown -h -f
command) -
help
is a short form to display help (alias to*:help
command) -
man
is the same as help (alias tohelp
command) -
log:list
displays all loggers and level (alias tolog:get ALL
command)
You can create your own aliases in the etc/shell.init.script
file.
15.8.3.4. Key binding
Like on most Unix environment, Karaf console support some key bindings:
- the arrows key to navigate in the commands history
- CTRL-D to logout/shutdown Karaf
- CTRL-R to search previously executed command
- CTRL-U to remove the current line
15.8.3.5. Pipe
You can pipe the output of one command as input to another one. It’s a pipe, using the | character:
karaf@root()> feature:list |grep -i war pax-war | 4.1.4 | | Uninstalled | org.ops4j.pax.web-4.1.4 | Provide support of a full WebContainer pax-war-tomcat | 4.1.4 | | Uninstalled | org.ops4j.pax.web-4.1.4 | war | 4.0.0 | | Uninstalled | standard-4.0.0 | Turn Karaf as a full WebContainer blueprint-web | 4.0.0 | | Uninstalled | standard-4.0.0 | Provides an OSGI-aware Servlet ContextListener fo
15.8.3.6. Grep, more, find, …
Karaf console provides some core commands similar to Unix environment:
-
shell:alias
creates an alias to an existing command -
shell:cat
displays the content of a file or URL -
shell:clear
clears the current console display -
shell:completion
displays or change the current completion mode -
shell:date
displays the current date (optionally using a format) -
shell:each
executes a closure on a list of arguments -
shell:echo
echoes and prints arguments to stdout -
shell:edit
calls a text editor on the current file or URL -
shell:env
displays or sets the value of a shell session variable -
shell:exec
executes a system command -
shell:grep
prints lines matching the given pattern -
shell:head
displays the first line of the input -
shell:history
prints the commands history -
shell:if
allows you to use conditions (if, then, else blocks) in script -
shell:info
prints various information about the current Karaf instance -
shell:java
executes a Java application -
shell:less
file pager -
shell:logout
disconnects shell from current session -
shell:more
is a file pager -
shell:new
creates a new Java object -
shell:printf
formats and prints arguments -
shell:sleep
sleeps for a bit then wakes up -
shell:sort
writes sorted concatenation of all files to stdout -
shell:source
executes commands contained in a script -
shell:stack-traces-print
prints the full stack trace in the console when the execution of a command throws an exception -
shell:tac
captures the STDIN and returns it as a string -
shell:tail
displays the last lines of the input -
shell:threads
prints the current thread -
shell:watch
periodically executes a command and refresh the output -
shell:wc
prints newline, words, and byte counts for each file -
shell:while
loop while the condition is true
You don’t have to use the fully qualified name of the command, you can directly use the command name as long as it is unique. So you can use 'head' instead of 'shell:head'
Again, you can find details and all options of these commands using help
command or --help
option.
15.8.3.7. Scripting
The Apache Karaf Console supports a complete scripting language, similar to bash or csh on Unix.
The each
(shell:each
) command can iterate in a list:
karaf@root()> list = [1 2 3]; each ($list) { echo $it } 1 2 3
The same loop could be written with the shell:while
command:
karaf@root()> a = 0 ; while { %((a+=1) <= 3) } { echo $a } 1 2 3
You can create the list yourself (as in the previous example), or some commands can return a list too.
We can note that the console created a "session" variable with the name list
that you can access with $list
.
The $it
variable is an implicit one corresponding to the current object (here the current iterated value from the list).
When you create a list with []
, Apache Karaf console creates a Java ArrayList. It means that you can use methods available in the ArrayList objects (like get or size for instance):
karaf@root()> list = ["Hello" world]; echo ($list get 0) ($list get 1) Hello world
We can note here that calling a method on an object is directly using (object method argument)
. Here ($list get 0)
means $list.get(0)
where $list
is the ArrayList.
The class
notation will display details about the object:
karaf@root()> $list class ... ProtectionDomain ProtectionDomain null null <no principals> java.security.Permissions@6521c24e ( ("java.security.AllPermission" "<all permissions>" "<all actions>") ) Signers null SimpleName ArrayList TypeParameters [E]
You can "cast" a variable to a given type.
karaf@root()> ("hello world" toCharArray) [h, e, l, l, o, , w, o, r, l, d]
If it fails, you will see the casting exception:
karaf@root()> ("hello world" toCharArray)[0] Error executing command: [C cannot be cast to [Ljava.lang.Object;
You can "call" a script using the shell:source
command:
karaf@root> shell:source script.txt True!
where script.txt
contains:
foo = "foo" if { $foo equals "foo" } { echo "True!" }
The spaces are important when writing script. For instance, the following script is not correct:
if{ $foo equals "foo" } ...
and will fail with:
karaf@root> shell:source script.txt Error executing command: Cannot coerce echo "true!"() to any of []
because a space is missing after the if
statement.
As for the aliases, you can create init scripts in the etc/shell.init.script
file. You can also named you script with an alias. Actually, the aliases are just scripts.
See the Scripting section of the developers guide for details.
15.8.4. Security
The Apache Karaf console supports a Role Based Access Control (RBAC) security mechanism. It means that depending of the user connected to the console, you can define, depending of the user’s groups and roles, the permission to execute some commands, or limit the values allowed for the arguments.
Console security is detailed in the Security section of this user guide.
15.9. Provisioning
Apache Karaf supports the provisioning of applications and modules using the concept of Karaf Features.
15.9.1. Application
By provisioning application, it means install all modules, configuration, and transitive applications.
15.9.2. OSGi
It natively supports the deployment of OSGi applications.
An OSGi application is a set of OSGi bundles. An OSGi bundles is a regular jar file, with additional metadata in the jar MANIFEST.
In OSGi, a bundle can depend to other bundles. So, it means that to deploy an OSGi application, most of the time, you have to firstly deploy a lot of other bundles required by the application.
So, you have to find these bundles first, install the bundles. Again, these "dependency" bundles may require other bundles to satisfy their own dependencies.
More over, typically, an application requires configuration (see the [Configuration section|configuration] of the user guide). So, before being able to start your application, in addition of the dependency bundles, you have to create or deploy the configuration.
As we can see, the provisioning of an application can be very long and fastidious.
15.9.3. Feature and resolver
Apache Karaf provides a simple and flexible way to provision applications.
In Apache Karaf, the application provisioning is an Apache Karaf "feature".
A feature describes an application as:
- a name
- a version
- a optional description (eventually with a long description)
- a set of bundles
- optionally a set configurations or configuration files
- optionally a set of dependency features
When you install a feature, Apache Karaf installs all resources described in the feature. It means that it will automatically resolves and installs all bundles, configurations, and dependency features described in the feature.
The feature resolver checks the service requirements, and install the bundles providing the services matching the requirements. The default mode enables this behavior only for "new style" features repositories (basically, the features repositories XML with schema equal or greater to 1.3.0). It doesn’t apply for "old style" features repositories (coming from Karaf 2 or 3).
You can change the service requirements enforcement mode in etc/org.apache.karaf.features.cfg
file, using the serviceRequirements
property.
serviceRequirements=default
The possible values are:
- disable: service requirements are completely ignored, for both "old style" and "new style" features repositories
- default: service requirements are ignored for "old style" features repositories, and enabled for "new style" features repositories.
- enforce: service requirements are always verified, for "old style" and "new style" features repositories.
Additionally, a feature can also define requirements. In that case, Karaf can automatically additional bundles or features providing the capabilities to satisfy the requirements.
A feature has a complete lifecycle: install, start, stop, update, uninstall.
15.9.4. Features repositories
The features are described in a features XML descriptor. This XML file contains the description of a set of features.
A features XML descriptor is named a "features repository". Before being able to install a feature, you have to register the features repository that provides the feature (using feature:repo-add
command or FeatureMBean as described later).
For instance, the following XML file (or "features repository") describes the feature1
and feature2
features:
<features xmlns="http://karaf.apache.org/xmlns/features/v1.3.0"> <feature name="feature1" version="1.0.0"> <bundle>...</bundle> <bundle>...</bundle> </feature> <feature name="feature2" version="1.1.0"> <feature>feature1</feature> <bundle>...</bundle> </feature> </features>
We can note that the features XML has a schema. Take a look on [Features XML Schema section|provisioning-schema] of the user guide for details. The feature1
feature is available in version 1.0.0
, and contains two bundles. The <bundle/>
element contains a URL to the bundle artifact (see [Artifacts repositories and URLs section|urls] for details). If you install the feature1
feature (using feature:install
or the FeatureMBean as described later), Apache Karaf will automatically installs the two bundles described. The feature2
feature is available in version 1.1.0
, and contains a reference to the feature1
feature and a bundle. The <feature/>
element contains the name of a feature. A specific feature version can be defined using the version
attribute to the <feature/>
element (<feature version="1.0.0">feature1</feature>
). If the version
attribute is not specified, Apache Karaf will install the latest version available. If you install the feature2
feature (using feature:install
or the FeatureMBean as described later), Apache Karaf will automatically installs feature1
(if it’s not already installed) and the bundle.
A feature repository is registered using the URL to the features XML file.
The features state is stored in the Apache Karaf cache (in the KARAF_DATA
folder). You can restart Apache Karaf, the previously installed features remain installed and available after restart. If you do a clean restart or you delete the Apache Karaf cache (delete the KARAF_DATA
folder), all previously features repositories registered and features installed will be lost: you will have to register the features repositories and install features by hand again. To prevent this behaviour, you can specify features as boot features.
15.9.5. Boot features
A boot feature is automatically installed by Apache Karaf, even if it has not been previously installed using feature:install
or FeatureMBean.
The Apache Karaf features configuration is located in the etc/org.apache.karaf.features.cfg
configuration file.
This configuration file contains the two properties to use to define boot features:
-
featuresRepositories
contains a list (comma-separated) of features repositories (features XML) URLs. -
featuresBoot
contains a list (comma-separated) of features to install at boot.
To remove features from the featuresBoot
list in the etc/org.apache.karaf.features.cfg
configuration file:
-
Navigate to
etc/org.apache.karaf.features.cfg
. - Remove the undesired feature.
- Restart your container.
After the restart, the features will be present in the etc/org.apache.karaf.features.cfg
configuration file, but they will not be installed and the undesired feature or behavior will no longer be present or active.
Another way to clean up the featuresBoot
is to stop Karaf, update featuresBoot
, and remove the data folder.
15.9.6. Features upgrade
You can update a release by installing the same feature (with the same SNAPSHOT version or a different version).
Thanks to the features lifecycle, you can control the status of the feature (started, stopped, etc).
You can also use a simulation to see what the update will do.
15.9.7. Overrides
Bundles defined in features can be overridden by using a file etc/overrides.properties. Each line in the file defines one override. The syntax is: <bundle-uri>[;range="[min,max)"] The given bundle will override all bundles in feature definitions with the same symbolic name if the version of the override is greater than the version of the overridden bundle and the range matches. If no range is given then compatibility on the micro version level is assumed.
So for example the override mvn:org.ops4j.pax.logging/pax-logging-service/1.8.5 would overide pax-logging-service 1.8.3 but not 1.8.6 or 1.7.0.
15.9.8. Feature bundles
15.9.8.1. Start Level
By default, the bundles deployed by a feature will have a start-level equals to the value defined in the etc/config.properties
configuration file, in the karaf.startlevel.bundle
property.
This value can be "overrided" by the start-level
attribute of the <bundle/>
element, in the features XML.
<feature name="my-project" version="1.0.0"> <bundle start-level="80">mvn:com.mycompany.myproject/myproject-dao</bundle> <bundle start-level="85">mvn:com.mycompany.myproject/myproject-service</bundle> </feature>
The start-level attribute insure that the myproject-dao
bundle is started before the bundles that use it.
Instead of using start-level, a better solution is to simply let the OSGi framework know what your dependencies are by defining the packages or services you need. It is more robust than setting start levels.
15.9.8.2. Simulate, Start and stop
You can simulate the installation of a feature using the -t
option to feature:install
command.
You can install a bundle without starting it. By default, the bundles in a feature are automatically started.
A feature can specify that a bundle should not be started automatically (the bundle stays in resolved state). To do so, a feature can specify the start
attribute to false in the <bundle/>
element:
<feature name="my-project" version="1.0.0"> <bundle start-level="80" start="false">mvn:com.mycompany.myproject/myproject-dao</bundle> <bundle start-level="85" start="false">mvn:com.mycompany.myproject/myproject-service</bundle> </feature>
15.9.8.3. Dependency
A bundle can be flagged as being a dependency, using the dependency
attribute set to true on the <bundle/>
element.
This information can be used by resolvers to compute the full list of bundles to be installed.
15.9.9. Dependent features
A feature can depend to a set of other features:
<feature name="my-project" version="1.0.0"> <feature>other</feature> <bundle start-level="80" start="false">mvn:com.mycompany.myproject/myproject-dao</bundle> <bundle start-level="85" start="false">mvn:com.mycompany.myproject/myproject-service</bundle> </feature>
When the my-project
feature will be installed, the other
feature will be automatically installed as well.
It’s possible to define a version range for a dependent feature:
<feature name="spring-dm"> <feature version="[2.5.6,4)">spring</feature> ... </feature>
The feature with the highest version available in the range will be installed.
If a single version is specified, the range will be considered open-ended.
If nothing is specified, the highest available will be installed.
To specify an exact version, use a closed range such as [3.1,3.1]
.
15.9.9.1. Feature prerequisites
Prerequisite feature is special kind of dependency. If you will add prerequisite
attribute to dependant feature tag then it will force installation and also activation of bundles in dependant feature before installation of actual feature. This may be handy in case if bundles enlisted in given feature are not using pre installed URL such wrap
or war
.
15.9.10. Feature configurations
The <config/>
element in a feature XML allows a feature to create and/or populate a configuration (identified by a configuration PID).
<config name="com.foo.bar"> myProperty = myValue </config>
The name
attribute of the <config/>
element corresponds to the configuration PID (see the [Configuration section|configuration] for details).
The installation of the feature will have the same effect as dropping a file named com.foo.bar.cfg
in the etc
folder.
The content of the <config/>
element is a set of properties, following the key=value standard.
15.9.11. Feature configuration files
Instead of using the <config/>
element, a feature can specify <configfile/>
elements.
<configfile finalname="/etc/myfile.cfg" override="false">URL</configfile>
Instead of directly manipulating the Apache Karaf configuration layer (as when using the <config/>
element), the <configfile/>
element takes directly a file specified by a URL, and copy the file in the location specified by the finalname
attribute.
If not specified, the location is relative from the KARAF_BASE
variable. It’s also possible to use variable like ${karaf.home}, ${karaf.base}, ${karaf.etc}, or even system properties.
For instance:
<configfile finalname="${karaf.etc}/myfile.cfg" override="false">URL</configfile>
If the file is already present at the desired location it is kept and the deployment of the configuration file is skipped, as a already existing file might contain customization. This behaviour can be overriden by override
set to true.
The file URL is any URL supported by Apache Karaf (see the [Artifacts repositories and URLs|urls] of the user guide for details).
15.9.11.1. Requirements
A feature can also specify expected requirements. The feature resolver will try to satisfy the requirements. For that, it checks the features and bundles capabilities and will automatically install the bundles to satisfy the requirements.
For instance, a feature can contain:
<requirement>osgi.ee;filter:="(&(osgi.ee=JavaSE)(!(version>=1.8)))"</requirement>
The requirement specifies that the feature will work by only if the JDK version is not 1.8 (so basically 1.7).
The features resolver is also able to refresh the bundles when an optional dependency is satisfy, rewiring the optional import.
15.9.12. Commands
15.9.12.1. feature:repo-list
The feature:repo-list
command lists all registered features repository:
karaf@root()> feature:repo-list Repository | URL -------------------------------------------------------------------------------------- org.ops4j.pax.cdi-0.12.0 | mvn:org.ops4j.pax.cdi/pax-cdi-features/0.12.0/xml/features org.ops4j.pax.web-4.1.4 | mvn:org.ops4j.pax.web/pax-web-features/4.1.4/xml/features standard-4.0.0 | mvn:org.apache.karaf.features/standard/4.0.0/xml/features enterprise-4.0.0 | mvn:org.apache.karaf.features/enterprise/4.0.0/xml/features spring-4.0.0 | mvn:org.apache.karaf.features/spring/4.0.0/xml/features
Each repository has a name and the URL to the features XML.
Apache Karaf parses the features XML when you register the features repository URL (using feature:repo-add
command or the FeatureMBean as described later). If you want to force Apache Karaf to reload the features repository URL (and so update the features definition), you can use the -r
option:
karaf@root()> feature:repo-list -r Reloading all repositories from their urls Repository | URL -------------------------------------------------------------------------------------- org.ops4j.pax.cdi-0.12.0 | mvn:org.ops4j.pax.cdi/pax-cdi-features/0.12.0/xml/features org.ops4j.pax.web-4.1.4 | mvn:org.ops4j.pax.web/pax-web-features/4.1.4/xml/features standard-4.0.0 | mvn:org.apache.karaf.features/standard/4.0.0/xml/features enterprise-4.0.0 | mvn:org.apache.karaf.features/enterprise/4.0.0/xml/features spring-4.0.0 | mvn:org.apache.karaf.features/spring/4.0.0/xml/features
15.9.12.2. feature:repo-add
To register a features repository (and so having new features available in Apache Karaf), you have to use the feature:repo-add
command.
The feature:repo-add
command requires the name/url
argument. This argument accepts:
- a feature repository URL. It’s an URL directly to the features XML file. Any URL described in the [Artifacts repositories and URLs section|urls] of the user guide is supported.
-
a feature repository name defined in the
etc/org.apache.karaf.features.repos.cfg
configuration file.
The etc/org.apache.karaf.features.repos.cfg
defines a list of "pre-installed/available" features repositories:
################################################################################ # # 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 # the License. You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # 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. # ################################################################################ # # This file describes the features repository URL # It could be directly installed using feature:repo-add command # enterprise=mvn:org.apache.karaf.features/enterprise/LATEST/xml/features spring=mvn:org.apache.karaf.features/spring/LATEST/xml/features cellar=mvn:org.apache.karaf.cellar/apache-karaf-cellar/LATEST/xml/features cave=mvn:org.apache.karaf.cave/apache-karaf-cave/LATEST/xml/features camel=mvn:org.apache.camel.karaf/apache-camel/LATEST/xml/features camel-extras=mvn:org.apache-extras.camel-extra.karaf/camel-extra/LATEST/xml/features cxf=mvn:org.apache.cxf.karaf/apache-cxf/LATEST/xml/features cxf-dosgi=mvn:org.apache.cxf.dosgi/cxf-dosgi/LATEST/xml/features cxf-xkms=mvn:org.apache.cxf.services.xkms/cxf-services-xkms-features/LATEST/xml activemq=mvn:org.apache.activemq/activemq-karaf/LATEST/xml/features jclouds=mvn:org.apache.jclouds.karaf/jclouds-karaf/LATEST/xml/features openejb=mvn:org.apache.openejb/openejb-feature/LATEST/xml/features wicket=mvn:org.ops4j.pax.wicket/features/LATEST/xml/features hawtio=mvn:io.hawt/hawtio-karaf/LATEST/xml/features pax-cdi=mvn:org.ops4j.pax.cdi/pax-cdi-features/LATEST/xml/features pax-jdbc=mvn:org.ops4j.pax.jdbc/pax-jdbc-features/LATEST/xml/features pax-jpa=mvn:org.ops4j.pax.jpa/pax-jpa-features/LATEST/xml/features pax-web=mvn:org.ops4j.pax.web/pax-web-features/LATEST/xml/features pax-wicket=mvn:org.ops4j.pax.wicket/pax-wicket-features/LATEST/xml/features ecf=http://download.eclipse.org/rt/ecf/latest/site.p2/karaf-features.xml decanter=mvn:org.apache.karaf.decanter/apache-karaf-decanter/LATEST/xml/features
You can directly provide a features repository name to the feature:repo-add
command. For install, to install PAX JDBC, you can do:
karaf@root()> feature:repo-add pax-jdbc Adding feature url mvn:org.ops4j.pax.jdbc/pax-jdbc-features/LATEST/xml/features
When you don’t provide the optional version
argument, Apache Karaf installs the latest version of the features repository available. You can specify a target version with the version
argument:
karaf@root()> feature:repo-add pax-jdbc 1.3.0 Adding feature url mvn:org.ops4j.pax.jdbc/pax-jdbc-features/1.3.0/xml/features
Instead of providing a features repository name defined in the etc/org.apache.karaf.features.repos.cfg
configuration file, you can directly provide the features repository URL to the feature:repo-add
command:
karaf@root()> feature:repo-add mvn:org.ops4j.pax.jdbc/pax-jdbc-features/1.3.0/xml/features Adding feature url mvn:org.ops4j.pax.jdbc/pax-jdbc-features/1.3.0/xml/features
By default, the feature:repo-add
command just registers the features repository, it doesn’t install any feature. If you specify the -i
option, the feature:repo-add
command registers the features repository and installs all features described in this features repository:
karaf@root()> feature:repo-add -i pax-jdbc
15.9.12.3. feature:repo-refresh
Apache Karaf parses the features repository XML when you register it (using feature:repo-add
command or the FeatureMBean). If the features repository XML changes, you have to indicate to Apache Karaf to refresh the features repository to load the changes.
The feature:repo-refresh
command refreshes the features repository.
Without argument, the command refreshes all features repository:
karaf@root()> feature:repo-refresh Refreshing feature url mvn:org.ops4j.pax.cdi/pax-cdi-features/0.12.0/xml/features Refreshing feature url mvn:org.ops4j.pax.web/pax-web-features/4.1.4/xml/features Refreshing feature url mvn:org.apache.karaf.features/standard/4.0.0/xml/features Refreshing feature url mvn:org.apache.karaf.features/enterprise/4.0.0/xml/features Refreshing feature url mvn:org.apache.karaf.features/spring/4.0.0/xml/features
Instead of refreshing all features repositories, you can specify the features repository to refresh, by providing the URL or the features repository name (and optionally version):
karaf@root()> feature:repo-refresh mvn:org.apache.karaf.features/standard/4.0.0/xml/features Refreshing feature url mvn:org.apache.karaf.features/standard/4.0.0/xml/features
karaf@root()> feature:repo-refresh pax-jdbc Refreshing feature url mvn:org.ops4j.pax.jdbc/pax-jdbc-features/LATEST/xml/features
15.9.12.4. feature:repo-remove
The feature:repo-remove
command removes a features repository from the registered ones.
The feature:repo-remove
command requires an argument:
-
the features repository name (as displayed in the repository column of the
feature:repo-list
command output) -
the features repository URL (as displayed in the URL column of the
feature:repo-list
command output)
karaf@root()> feature:repo-remove org.ops4j.pax.jdbc-1.3.0
karaf@root()> feature:repo-remove mvn:org.ops4j.pax.jdbc/pax-jdbc-features/1.3.0/xml/features
By default, the feature:repo-remove
command just removes the features repository from the registered ones: it doesn’t uninstall the features provided by the features repository.
If you use -u
option, the feature:repo-remove
command uninstalls all features described by the features repository:
karaf@root()> feature:repo-remove -u org.ops4j.pax.jdbc-1.3.0
15.9.12.5. feature:list
The feature:list
command lists all available features (provided by the different registered features repositories):
Name | Version | Required | State | Repository | Description ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- pax-cdi | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Provide CDI support pax-cdi-1.1 | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Provide CDI 1.1 support pax-cdi-1.2 | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Provide CDI 1.2 support pax-cdi-weld | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Weld CDI support pax-cdi-1.1-weld | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Weld CDI 1.1 support pax-cdi-1.2-weld | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Weld CDI 1.2 support pax-cdi-openwebbeans | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | OpenWebBeans CDI support pax-cdi-web | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Web CDI support pax-cdi-1.1-web | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Web CDI 1.1 support ...
If you want to order the features by alphabetical name, you can use the -o
option:
karaf@root()> feature:list -o Name | Version | Required | State | Repository | Description ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- deltaspike-core | 1.2.1 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Apache Deltaspike core support deltaspike-data | 1.2.1 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Apache Deltaspike data support deltaspike-jpa | 1.2.1 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Apache Deltaspike jpa support deltaspike-partial-bean | 1.2.1 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Apache Deltaspike partial bean support pax-cdi | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Provide CDI support pax-cdi-1.1 | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Provide CDI 1.1 support pax-cdi-1.1-web | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Web CDI 1.1 support pax-cdi-1.1-web-weld | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Weld Web CDI 1.1 support pax-cdi-1.1-weld | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Weld CDI 1.1 support pax-cdi-1.2 | 0.12.0 | | Uninstalled | org.ops4j.pax.cdi-0.12.0 | Provide CDI 1.2 support ...
By default, the feature:list
command displays all features, whatever their current state (installed or not installed).
Using the -i
option displays only installed features:
karaf@root()> feature:list -i Name | Version | Required | State | Repository | Description ------------------------------------------------------------------------------------------------------------------- aries-proxy | 4.0.0 | | Started | standard-4.0.0 | Aries Proxy aries-blueprint | 4.0.0 | x | Started | standard-4.0.0 | Aries Blueprint feature | 4.0.0 | x | Started | standard-4.0.0 | Features Support shell | 4.0.0 | x | Started | standard-4.0.0 | Karaf Shell shell-compat | 4.0.0 | x | Started | standard-4.0.0 | Karaf Shell Compatibility deployer | 4.0.0 | x | Started | standard-4.0.0 | Karaf Deployer bundle | 4.0.0 | x | Started | standard-4.0.0 | Provide Bundle support config | 4.0.0 | x | Started | standard-4.0.0 | Provide OSGi ConfigAdmin support diagnostic | 4.0.0 | x | Started | standard-4.0.0 | Provide Diagnostic support instance | 4.0.0 | x | Started | standard-4.0.0 | Provide Instance support jaas | 4.0.0 | x | Started | standard-4.0.0 | Provide JAAS support log | 4.0.0 | x | Started | standard-4.0.0 | Provide Log support package | 4.0.0 | x | Started | standard-4.0.0 | Package commands and mbeans service | 4.0.0 | x | Started | standard-4.0.0 | Provide Service support system | 4.0.0 | x | Started | standard-4.0.0 | Provide System support kar | 4.0.0 | x | Started | standard-4.0.0 | Provide KAR (KARaf archive) support ssh | 4.0.0 | x | Started | standard-4.0.0 | Provide a SSHd server on Karaf management | 4.0.0 | x | Started | standard-4.0.0 | Provide a JMX MBeanServer and a set of MBeans in wrap | 0.0.0 | x | Started | standard-4.0.0 | Wrap URL handler
15.9.12.6. feature:install
The feature:install
command installs a feature.
It requires the feature
argument. The feature
argument is the name of the feature, or the name/version of the feature. If only the name of the feature is provided (not the version), the latest version available will be installed.
karaf@root()> feature:install eventadmin
We can simulate an installation using -t
or --simulate
option: it just displays what it would do, but it doesn’t do it:
karaf@root()> feature:install -t -v eventadmin Adding features: eventadmin/[4.0.0,4.0.0] No deployment change. Managing bundle: org.apache.felix.metatype / 1.0.12
You can specify a feature version to install:
karaf@root()> feature:install eventadmin/4.0.0
By default, the feature:install
command is not verbose. If you want to have some details about actions performed by the feature:install
command, you can use the -v
option:
karaf@root()> feature:install -v eventadmin Adding features: eventadmin/[4.0.0,4.0.0] No deployment change. Done.
If a feature contains a bundle which is already installed, by default, Apache Karaf will refresh this bundle. Sometime, this refresh can cause issue to other running applications. If you want to disable the auto-refresh of installed bundles, you can use the -r
option:
karaf@root()> feature:install -v -r eventadmin Adding features: eventadmin/[4.0.0,4.0.0] No deployment change. Done.
You can decide to not start the bundles installed by a feature using the -s
or --no-auto-start
option:
karaf@root()> feature:install -s eventadmin
15.9.12.7. feature:start
By default, when you install a feature, it’s automatically installed. However, you can specify the -s
option to the feature:install
command.
As soon as you install a feature (started or not), all packages provided by the bundles defined in the feature will be available, and can be used for the wiring in other bundles.
When starting a feature, all bundles are started, and so, the feature also exposes the services.
15.9.12.8. feature:stop
You can also stop a feature: it means that all services provided by the feature will be stop and removed from the service registry. However, the packages are still available for the wiring (the bundles are in resolved state).
15.9.12.9. feature:uninstall
The feature:uninstall
command uninstalls a feature. As the feature:install
command, the feature:uninstall
command requires the feature
argument. The feature
argument is the name of the feature, or the name/version of the feature. If only the name of the feature is provided (not the version), the latest version available will be installed.
karaf@root()> feature:uninstall eventadmin
The features resolver is involved during feature uninstallation: transitive features installed by the uninstalled feature can be uninstalled themselves if not used by other feature.
15.9.13. Deployer
You can "hot deploy" a features XML by dropping the file directly in the deploy
folder.
Apache Karaf provides a features deployer.
When you drop a features XML in the deploy folder, the features deployer does: * register the features XML as a features repository * the features with install
attribute set to "auto" will be automatically installed by the features deployer.
For instance, dropping the following XML in the deploy folder will automatically install feature1 and feature2, whereas feature3 won’t be installed:
<?xml version="1.0" encoding="UTF-8"?> <features name="my-features" xmlns="http://karaf.apache.org/xmlns/features/v1.3.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://karaf.apache.org/xmlns/features/v1.3.0 http://karaf.apache.org/xmlns/features/v1.3.0"> <feature name="feature1" version="1.0" install="auto"> ... </feature> <feature name="feature2" version="1.0" install="auto"> ... </feature> <feature name="feature3" version="1.0"> ... </feature> </features>
15.9.14. JMX FeatureMBean
On the JMX layer, you have a MBean dedicated to the management of the features and features repositories: the FeatureMBean.
The FeatureMBean object name is: org.apache.karaf:type=feature,name=*
.
15.9.14.1. Attributes
The FeatureMBean provides two attributes:
-
Features
is a tabular data set of all features available. -
Repositories
is a tabular data set of all registered features repositories.
The Repositories
attribute provides the following information:
-
Name
is the name of the features repository. -
Uri
is the URI to the features XML for this repository. -
Features
is a tabular data set of all features (name and version) provided by this features repository. -
Repositories
is a tabular data set of features repositories "imported" in this features repository.
The Features
attribute provides the following information:
-
Name
is the name of the feature. -
Version
is the version of the feature. -
Installed
is a boolean. If true, it means that the feature is currently installed. -
Bundles
is a tabular data set of all bundles (bundles URL) described in the feature. -
Configurations
is a tabular data set of all configurations described in the feature. -
Configuration Files
is a tabular data set of all configuration files described in the feature. -
Dependencies
is a tabular data set of all dependent features described in the feature.
15.9.14.2. Operations
-
addRepository(url)
adds the features repository with theurl
. Theurl
can be aname
as in thefeature:repo-add
command. -
addRepository(url, install)
adds the features repository with theurl
and automatically installs all bundles ifinstall
is true. Theurl
can be aname
like in thefeature:repo-add
command. -
removeRepository(url)
removes the features repository with theurl
. Theurl
can be aname
as in thefeature:repo-remove
command. -
installFeature(name)
installs the feature with thename
. -
installFeature(name, version)
installs the feature with thename
andversion
. -
installFeature(name, noClean, noRefresh)
installs the feature with thename
without cleaning the bundles in case of failure, and without refreshing already installed bundles. -
installFeature(name, version, noClean, noRefresh) ` installs the feature with the `name
andversion
without cleaning the bundles in case of failure, and without refreshing already installed bundles. -
uninstallFeature(name)
uninstalls the feature with thename
. -
uninstallFeature(name, version)
uninstalls the feature with thename
andversion
.
15.9.14.3. Notifications
The FeatureMBean sends two kind of notifications (on which you can subscribe and react):
- When a feature repository changes (added or removed).
- When a feature changes (installed or uninstalled).