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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
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Using the admin console commands
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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 chapter "Admin Console Commands" in "Console Reference".

Installing the admin console commands
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The admin commands are not installed by default. To install the command set, install the admin feature with the following command: 
JBossFuse:karaf@root> features:install admin
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Cloning a container
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When you clone a container using the admin:clone command, you create a new child container which is an exact copy of the parent container in its current state. For example, if you clone the root container, the child gets the same configuration as the root container. Note that the child container has the same port numbers as the parent by default. After cloning, therefore, it is a good idea to customize the child's port numbers, to avoid clashes.
In the case of the SSH port, it is possible to customize the port when you create the child, by specifying the -s option. For example, to create a new child with the SSH port number of 8102: 
JBossFuse:karaf@root> admin:clone -s 8102 root cloned
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Creating a Karaf child container
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The admin:create command creates a new Apache Karaf child container. That is, the new child container is not a full JBoss Fuse container, and is missing many of the standard bundles, features, and feature repositories that are normally available in a JBoss Fuse container. What you get is effectively a plain Apache Karaf container with JBoss Fuse branding. Additional feature repositories or features that you require will have to be added to the child manually.
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 child container is assigned an SSH port number based on an incremental count starting at 8101.

Example 9.1. Creating a Runtime Instance

JBossFuse:karaf@root> admin:create finn
Creating new instance on SSH port 8102 and RMI ports 1100/44445 at:
  /home/jdoe/apps/fuse/jboss-fuse-6.3.0.redhat-xxx/instances/finn
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Changing a child's SSH port
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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
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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
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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
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Connecting to a child container
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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>
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Stopping a child container
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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
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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
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To change the Java options in a child instance, use the admin:change-opts command. For example, you could change the amount 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"
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These changes will take effect when you restart the child container.

Using the admin script
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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 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.
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For example, to list all of the JBoss Fuse containers on your host machine, type:
Windows 
admin.bat list
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Linux or UNIX 
./admin list
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