17.5. Clustering

1. Modify the following script to suit your environment.

   Copy the following script into a text editor. If you use a different profile on a managed domain, change the profile name. If you use a standalone server, remove the /profile=full-ha portion of the commands. Modify the properties listed at the bottom of the command as follows. Each of these properties is optional.

   initial_hosts

   A comma-separated list of hosts, using the syntax HOST[PORT], that are considered well-known and will be available to look up the initial membership.

   port_range

   If desired, you can assign a port range. If you assign a port range of 2, and the initial port for a host is 7600, then TCPPING will attempt to contact the host on ports 7600-7602. The port range applies to each address specified in initial_hosts. This property is optional.

   timeout

   An optional timeout value, in milliseconds, for cluster members.

   num_initial_members

   The number of nodes before the cluster is considered to be complete. This property is optional.

   batch
   ##  If  tcp  is already added then you can remove it  ##
   /profile=full-ha/subsystem=jgroups/stack=tcp:remove
   /profile=full-ha/subsystem=jgroups/stack=tcp:add(transport={"type" =>"TCP", "socket-binding" => "jgroups-tcp"})
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=TCPPING)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=MERGE2)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=FD_SOCK,socket-binding=jgroups-tcp-fd)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=FD)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=VERIFY_SUSPECT)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=BARRIER)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=pbcast.NAKACK)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=UNICAST2)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=pbcast.STABLE)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=pbcast.GMS)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=UFC)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=MFC)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=FRAG2)
   /profile=full-ha/subsystem=jgroups/stack=tcp/:add-protocol(type=RSVP)
   /profile=full-ha/subsystem=jgroups:write-attribute(name=default-stack,value=tcp)
   run-batch
   /profile=full-ha/subsystem=jgroups/stack=tcp/protocol=TCPPING/property=initial_hosts/:add(value="HostA[7600],HostB[7600]")
   /profile=full-ha/subsystem=jgroups/stack=tcp/protocol=TCPPING/property=port_range/:add(value=0)
   /profile=full-ha/subsystem=jgroups/stack=tcp/protocol=TCPPING/property=timeout/:add(value=3000)
   /profile=full-ha/subsystem=jgroups/stack=tcp/protocol=TCPPING/property=num_initial_members/:add(value=3)

2. Run the script in batch mode.

   Warning

   The servers running the profile have to be shutdown before executing the batch file.
   In a terminal emulator, navigate to the directory containing the jboss-cli.sh script and enter the command

   ./jboss-cli.sh -c --file=SCRIPT_NAME

   where SCRIPT_NAME is the name and path containing the script.

Procedure 17.11. 

1. Modify the Apache HTTP Server configuration.

   Modify the Apache HTTP Server configuration to disable server advertising and to use a proxy list instead. The proxy list is configured on the worker, and contains all of the mod_cluster-enabled Web servers to which the worker can talk.
   The mod_cluster configuration for the Web server is located in HTTPD_HOME. See Section 17.6.3, “Install the mod_cluster Module Into Apache HTTP Server or JBoss Enterprise Web Server (Zip)” and Section 17.6.5, “Configure Server Advertisement Properties for Your mod_cluster-enabled Web Server” for more information about the file itself. Open the file containing the virtual host which listens for MCPM requests (using the EnableMCPMReceive directive), and disable server advertising by changing the ServerAdvertise directive as follows.

   ServerAdvertise Off

2. Disable advertising within the mod_cluster subsystem of JBoss EAP 6, and provide a list of proxies.

   You can disable advertising for the mod_cluster subsystem and provide a list of proxies, by using the web-based Management Console or the command-line Management CLI. The list of proxies is necessary because the mod_cluster subsystem will not be able to automatically discover proxies if advertising is disabled.

   • Management Console

     If you use a managed domain, you can only configure mod_cluster in profiles where it is enabled, such as the ha and full-ha profiles.
     1. Log in to the Management Console and select the Configuration tab at the top of the screen. If you use a managed domain, select either the ha or full-ha profile from the Profile drop-down menu at the top left.
     2. Expand the Subsystems menu then expand the Web menu and select mod_cluster.
     3. Click Edit under the Advertising tab under mod_cluster. To disable advertising, clear the check box next to Advertise, and click Save.
        

        Figure 17.1. mod_cluster Advertising Configuration Screen

     4. Click the Proxies tab. Click Edit and enter a list of proxy servers in the Proxy List field. The correct syntax is a comma-separated list of HOSTNAME:PORT strings, like the following:

        10.33.144.3:6666,10.33.144.1:6666

        Click the Save button to finish.

   • Management CLI

     The following two Management CLI commands create the same configuration as the Management Console instructions above. They assume that you run a managed domain and that your server group uses the full-ha profile. If you use a different profile, change its name in the commands. If you use a standalone server using the standalone-ha profile, remove the /profile=full-ha portion of the commands.

     /profile=full-ha/subsystem=modcluster/mod-cluster-config=configuration/:write-attribute(name=advertise,value=false)
     
     /profile=full-ha/subsystem=modcluster/mod-cluster-config=configuration/:write-attribute(name=proxy-list,value="10.33.144.3:6666,10.33.144.1:6666")

1. Remove the broadcast-groups and discovery-groups:

   <broadcast-groups>
       <broadcast-group name="bg-group1">
           <socket-binding>messaging-group</socket-binding>
           <broadcast-period>5000</broadcast-period>
           <connector-ref>netty</connector-ref>
       </broadcast-group>
   </broadcast-groups>
   <discovery-groups>
       <discovery-group name="dg-group1">
           <socket-binding>messaging-group</socket-binding>
           <refresh-timeout>10000</refresh-timeout>
       </discovery-group>
   </discovery-groups
   

2. Optionally, remove the "messaging-group" socket-binding:

   <socket-binding name="messaging-group" port="0" multicast-address="${jboss.messaging.group.address:231.7.7.7}" multicast-port="${jboss.messaging.group.port:9876}"/>

3. Configure the appropriate Netty connector(s) - one for each of the other nodes in the cluster.

   For example, if the cluster is 3 nodes then configure 2 Netty connectors, etc., if the cluster is 2 nodes then configure 1 Netty connector, etc. Here is a sample configuration for a 3-node cluster:

   <netty-connector name="other-cluster-node1" socket-binding="other-cluster-node1"/>
   <netty-connector name="other-cluster-node2" socket-binding="other-cluster-node2"/>

4. Configure the related socket bindings.

   Note

   The system property substitution can be used for either "host" or "port", if required.

   <outbound-socket-binding name="other-cluster-node1">
       <remote-destination host="otherNodeHostName1" port="5445"/>
   </outbound-socket-binding>
   <outbound-socket-binding name="other-cluster-node2">
       <remote-destination host="otherNodeHostName2" port="5445"/>
   </outbound-socket-binding>

5. Configure the cluster-connection to use these connectors instead of the discovery-group, which is used by default:

   <cluster-connection name="my-cluster">
       <address>jms</address>
       <connector-ref>netty</connector-ref>
       <static-connectors>
           <connector-ref>other-cluster-node1</connector-ref>
           <connector-ref>other-cluster-node2</connector-ref>
       </static-connectors>
   </cluster-connection>

   This process has to be repeated on each of the cluster nodes so that each node has connectors to every other node in the cluster.

   Note

   Do not configure a node with a connection to itself. This is considered as a misconfiguration.