Chapter 9. Managing Child Containers

Abstract

A child container is a container that shares a common Red Hat JBoss Fuse runtime with a parent container, but has its own configuration files, runtime information, logs and temporary files. The child container functions as an independent container into which you can deploy bundles.

9.1. Standalone Child Containers

Using the admin console commands

The admin console commands allow you to create and manage instances of the JBoss Fuse runtime on the same machine. Each new runtime is a child instance of the runtime that created it. You can easily manage the children using names instead of network addresses. For details on the admin commands, see Admin Console Commands.

Creating child containers

You create a new runtime container by typing admin:create in the JBoss Fuse console.
As shown in Example 9.1, “Creating a Runtime Instance”, admin:create causes the container to create a new child container in the active container's instances/containerName directory. The new container is a direct copy of its parent. The only difference between parent and child is the port number they listen on. The child container is assigned an SSH port number based on an incremental count starting at 8101.

Example 9.1. Creating a Runtime Instance

FuseESB@root>admin:create finn
Creating new instance on port 8106 at: /home/fuse/esb4/instances/finn Creating dir: /home/fuse/esb4/instances/finn/bin Creating dir: /home/fuse/esb4/instances/finn/etc Creating dir: /home/fuse/esb4/instances/finn/system Creating dir: /home/fuse/esb4/instances/finn/deploy Creating dir: /home/fuse/esb4/instances/finn/data Creating file: /home/fuse/esb4/instances/finn/etc/config.properties Creating file: /home/fuse/esb4/instances/finn/etc/java.util.logging.properties Creating file: /home/fuse/esb4/instances/finn/etc/org.apache.felix.fileinstall-deploy.cfg Creating file: /home/fuse/esb4/instances/finn/etc/org.apache.karaf.log.cfg Creating file: /home/fuse/esb4/instances/finn/etc/org.apache.karaf.features.cfg Creating file: /home/fuse/esb4/instances/finn/etc/org.apache.karaf.management.cfg Creating file: /home/fuse/esb4/instances/finn/etc/org.ops4j.pax.logging.cfg Creating file: /home/fuse/esb4/instances/finn/etc/org.ops4j.pax.url.mvn.cfg Creating file: /home/fuse/esb4/instances/finn/etc/startup.properties Creating file: /home/fuse/esb4/instances/finn/etc/system.properties Creating file: /home/fuse/esb4/instances/finn/etc/org.apache.karaf.shell.cfg Creating file: /home/fuse/esb4/instances/finn/bin/karaf Creating file: /home/fuse/esb4/instances/finn/bin/start Creating file: /home/fuse/esb4/instances/finn/bin/stop

Changing a child's SSH port

You can change the SSH port number assigned to a child container using the admin:change-port command. The syntax for the command is:

admin:change-port { containerName } { portNumber }

Important
You can only use the admin:change-port command on stopped containers.

Starting child containers

New containers are created in the stopped state. To start a child container and make it ready to host applications, use the admin:start command. This command takes a single argument, containerName, that identifies the child you want started.

Listing all child containers

To see a list of all the JBoss Fuse containers running under a particular installation, use the admin:list command:

Example 9.2. Listing Instances

JBossFuse:karaf@root>admin:list
  Port State Pid Name [ 8107] [Started ] [10628] harry [ 8101] [Started ] [20076] root [ 8106] [Started ] [15924] dick [ 8105] [Started ] [18224] tom

Connecting to a child container

You can connect to a started child container's remote console using the admin:connect command.As shown in Example 9.3, “Admin connect Command”, this command takes three arguments:

Example 9.3. Admin connect Command

admin:connect { containerName } { -u username } { -p password }

containerName
The name of the child to which you want to connect.
-u username
The username used to connect to the child's remote console. Use valid JAAS user credentials that have admin privileges (see Chapter 14, Configuring JAAS Security).
-p password
This argument specifies the password used to connect to the child's remote console.
Once you are connected to the child container., the prompt changes to display the name of the current instance, as shown: 
JBossFuse:karaf@harry>

Stopping a child container

To stop a child container, from within the container itself, type osgi:shutdown or simply shutdown.
To stop a child container remotely—in other words, from a parent or sibling instance—type admin:stop containerName.

Destroying a child container

You can permanently delete a stopped child container using the admin:destroy containerName command.
Important
You can only remove stopped children.

Changing the JVM options on a child container

To change the Java options in a child instance, use the admin:change-opts command. For example, you could change the amamount of memory allocated to the child container's JVM, as follows: 
JBossFuse:karaf@harry> admin:change-opts tom "-server -Xms128M -Xmx1345m -Dcom.sun.management.jmxremote"
These changes will take effect when you restart the child container.

Using the admin script

You can also use manage a JBoss Fuse container running in server mode without starting a new instance of the runtime. The admin script in the InstallDir/bin directory provides the all of the admin console commands except for admin:connect.

Example 9.4. The admin Script

admin.bat: Ignoring predefined value for KARAF_HOME Available commands: change-port - Changes the port of an existing container instance. create - Creates a new container instance. destroy - Destroys an existing container instance. list - List all existing container instances. start - Starts an existing container instance. stop - Stops an existing container instance. Type 'command --help' for more help on the specified command.
For example, to list all of the JBoss Fuse containers on your host machine, type:
Windows 
admin.bat list
*NIX 
./admin list