11.4. Starting the JBoss ON Agent

The JBoss ON agent can be started manually or can be configured to start and run as a system service.

11.4.1. Starting the JBoss ON Agent (Basic)

The agent is started and runs using a script in the agent's bin/ directory. Unlike the server start script, which starts the server process and then exits the script, the agent script remains open, with a prompt to accept further input if necessary. (Usually, the script can simply be started and left to run in the background.)
/opt/rhq-agent/bin/rhq-agent.sh

RHQ 2.4.0-SNAPSHOT [cda7569] (Tue Apr 13 13:39:16 EDT 2010)
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Most of the time, the JBoss ON agent can run without any additional options or settings. All of the available options for the rhq-agent.sh script are listed in Table 11.15, “Options for the rhq-agent.sh Script”. Additional configuration options can be set by editing the rhq-agent-env.sh script file.

TIP

If there are any errors when starting the JBoss ON agent, run the agent start script with the --cleanconfig to wipe the previous agent configuration and start fresh.

11.4.2. Running the Agent as a Windows Service

IMPORTANT

The agent does not prompt for the configuration when it is started as a service. The agent must either be pre-configured or have already been started once and the configuration entered. Both options are described in the Installation Guide.
  1. Edit the rhq-agent-wrapper.bat script and set the environment variable to define the system user as whom the init script will run. There are two options:
    • RHQ_AGENT_RUN_AS explicitly sets the user account name. This must match the format of a Windows user account name, DOMAIN\username.
    • RHQ_AGENT_RUN_AS_ME forces the agent to run as whoever the current user is; this uses the format . \ %USERNAME %. If both environment variables are defined, this variable overrides RHQ_AGENT_RUN_AS.

    NOTE

    Before setting RHQ_AGENT_RUN_AS_ME or RHQ_AGENT_RUN_AS, make sure that the given user actually has permission to start services. If necessary, assign the user the appropriate rights. Assigning rights is covered in the Windows documentation.
    If neither variable is set, the agent init script runs as the System user.
    Other available environment variables are listed and defined in the comments in the rhq-agent-wrapper.bat script.
  2. Run the rhq-agent-wrapper.bat script to install the init script as a service. Use the install command to install the init script.
  3. When prompted, fill in the password for the system user as whom the service will run.
The agent service starts automatically when the Windows system boots. The service can be started or stopped through the Windows Services Administrative Tools.
The agent service can also be started and stopped through the rhq-agent-wrapper.bat script using the start and stop commands. The status command shows whether the agent init script is installed as a service and whether it is running. The remove command removes the agent init script as a service.
The JBoss ON agent Windows scripts use the Java Wrapper Service to control the service. A configuration file, agentRoot\bin\wrapper\rhq-agent-wrapper.conf, contains the service configuration properties. These are standard wrapper service properties; more information is available at http://wrapper.tanukisoftware.org/doc/english/properties.html.
There are some common properties to edit to custom the service:
  • wrapper.app.parameter.# set command-line options to pass to the agent. These are the same options listed in Section 11.9.3, “Agent Startup Options and Prompt Commands”. Each option requires its own configuration property. Properties must be placed in numeric order and the first two properties (wrapper.app.parameter.1 and wrapper.app.parameter.2) are reserved. Start with wrapper.app.parameter.3.
  • wrapper.java.additional.# set additional JVM options that are passed directly to the VM, corresponding to the -D and -X options. These also must be incremented numerically. wrapper.java.additional.1 always specifies the log configuration file.
  • wrapper.ntservice.starttype sets when to start the service. The default is AUTO_START, which starts the service when the system boots. To start the service manually, the value is DEMAND_START.

11.4.3. Running the Agent as a Daemon or init.d Service

IMPORTANT

The agent does not prompt for the configuration when it is started as a service. The agent must either be pre-configured or have already been started once and the configuration entered. Both options are described in the Installation Guide.
Once the agent is configured (or pre-configured), the agent can be started in two ways. The rhq-agent.sh script starts the agent and opens the command console. The rhq-agent-wrapper.sh script simply starts the agent daemon and exits. Both methods can have additional environment variables configured through the rhq-agent-env.sh script file.
The daemon can be started and run as a system service. On Red Hat Enterprise Linux, this is done by configuring /etc/init.d and then installing it using chkconfig. For Solaris and other Unix systems, this is done by configuring /etc/init.d and then using other system tools to set up the service.
  1. Make sure the agent is fully set up.
  2. Open the rhq-agent-env.sh file.
  3. Uncomment and configure the required environment variables for the agent's bin directory, the JDK directory, and the PID directory (which must be writable by the agent user).
    RHQ_AGENT_HOME=agentRoot/rhq-agent/bin/
    export RHQ_AGENT_JAVA_HOME=/usr
    PIDFILEDIR=/var/run

    NOTE

    When setting the PIDFILEDIR on Red Hat Enterprise Linux, edit the pidfile setting in the rhq-agent-wrapper.sh script file. The wrapper script value is used by chkconfig.
  4. Set any of the optional environment variables.
    • RHQ_AGENT_DEBUG enables debug logging.
    • RHQ_AGENT_JAVA_EXE_FILE_PATH specifies a Java executable.
    • RHQ_AGENT_JAVA_OPTS passes settings to the agent JVM.
    • RHQ_AGENT_ADDITIONAL_JAVA_OPTS passes additional Java options to the JVM.
  5. Log into the system as root.

    IMPORTANT

    The rest of this procedure describes how to configure the agent init script as a service on Red Hat Enterprise Linux. For other Unix systems, follow a similar procedure that corresponds to the specific platform.
  6. Symlink the rhq-agent-wrapper.sh file to /etc/init.d/. For example:
    # ln -s agentRoot/rhq-agent/bin/rhq-agent-wrapper.sh /etc/init.d/rhq-agent-wrapper.sh

    IMPORTANT

    On Solaris, symlinking the agent script file requires invoking readlink in rhq-agent-wrapper.sh. readlink is not supplied by default in some Solaris installations. Solaris users must download readlink from a source such as Sunfreeware.
  7. Register rhq-agent-wrapper.sh with chkconfig.
    # /sbin/chkconfig --add rhq-agent-wrapper.sh
  8. Enable the agent service to run at boot time and have it stop gracefully at when the system shuts down.
    # /sbin/chkconfig rhq-agent-wrapper.sh on
If the agent service should not be started when the system boots, turn the script off in chkconfig:
# /sbin/chkconfig rhq-agent-wrapper.sh off

11.4.4. Restarting the Agent and the JVM

The agent can be restarted without taking down the agent JVM process. It is also possible to restart both the agent and its JVM.
The agent is managed through a plug-in container managed by the JBoss ON server. The container loads and manages the lifecycle of all agents. Restarting the plug-in container restarts the agent and all its components without destroying the JVM.
  1. Select the Resources menu in the top navigation bar, and select the Servers menu item.
  2. Click the agent resource in the list.
  3. Click the Operations tab.
  4. Select and launch the Restart task.
Alternatively, both the agent and its JVM can be restarted (this can be useful if, for instance, the launcher script or the JVM options have been edited).
  1. Select the Resources menu in the top navigation bar, and select the Servers menu item.
  2. Click the agent resource in the list.
  3. Navigate to the launcher script child resource beneath the agent.
  4. Click the Operations tab for the launcher script resource.
  5. Select and launch the Restart task.