WildFly Clustering without Multicast

External

• How do I switch clustering to TCP instead of multicast UDP in EAP 6? https://access.redhat.com/solutions/140103
• Configuring Cluster to run with TCP in Domain Mode of EAP6 using CLI https://access.redhat.com/solutions/146323

Internal

• WildFly Configuration
• JBoss Clustering without Multicast
• JGroups Protocol TCP

Procedure

Switch to a "tcp" Default Stack

Manual

Locate the "jgroups" subsystem in standalone.xml or domain.xml relevant profile, and set default-stack value to "tcp":

  ...
  <subsystem xmlns="urn:jboss:domain:jgroups:1.1" default-stack="tcp">
  ...

CLI

/subsystem=jgroups:write-attribute(name=default-stack,value=tcp)

Note that the operation requires reload, but you should reload the server configuration only after the entire procedure is complete (see reload)

Replace the MPING protocol with TCPPING

Manual

Locate the "tcp" stack inside the "jgroups" subsystem and replace the MPING protocol with TCPPING:

   ...
   <stack name="tcp">
      <transport type="TCP" socket-binding="jgroups-tcp"/>
      <protocol type="TCPPING">
          <property name="initial_hosts">1.2.3.4[7600],1.2.3.5[7600]</property>
          <property name="num_initial_members">2</property>
          <property name="port_range">0</property>
          <property name="timeout">2000</property>
       </protocol>
       <!--<protocol type="MPING" socket-binding="jgroups-mping"/>-->
       <protocol type="MERGE2"/>
       ...
   </stack>
  ...

If the domain model is used and the same profile is shared by several server groups, the "initial_hosts" property should be set on the server_group, as follows:

   ...
   <stack name="tcp">
      <transport type="TCP" socket-binding="jgroups-tcp"/>
      <protocol type="TCPPING">
          <property name="initial_hosts">${jboss.cluster.tcp.initial_hosts}</property>
          ...
       </protocol>
       ...
   </stack>
  ...

and the server group-specific values for the system property are set in the <server-group> element as follows:

    ...
    <server-groups>
        <server-group name="something" profile="ha">
            <socket-binding-group ref="ha-sockets"/>
            <system-properties>
              <property name="jboss.cluster.tcp.initial_hosts" value="1.2.3.4[7600],1.2.3.5[7600]" />
            </system-properties>
       </server-group>
      ,,,
    <server-groups>

CLI

Note that we can't simply remove MPING and add TCPING, the CLI API is not expressive enough to allow us to specify the protocol's position in the list. We need to replace MPING with TCPPING as follows:

/subsystem=jgroups/stack=tcp:remove-protocol(type=MPING)
/subsystem=jgroups/stack=tcp:add-protocol(type=TCPPING)
/subsystem=jgroups/stack=tcp/protocol=TCPPING/property=initial_hosts:add(value="1.2.3.4[7600],1.2.3.5[7600]")
/subsystem=jgroups/stack=tcp/protocol=TCPPING/property=num_initial_members:add(value=2)
/subsystem=jgroups/stack=tcp/protocol=TCPPING/property=port_range:add(value=0)
/subsystem=jgroups/stack=tcp/protocol=TCPPING/property=timeout:add(value=2000)

or

...
/subsystem=jgroups/stack=tcp/protocol=TCPPING/property=initial_hosts:add(value="${jboss.cluster.tcp.initial_hosts}")

Note that the operation requires reload (see reload)

Additional Verifications

• Verify that the cluster members do actually bind to the IP addresses specified in initial_hosts.
• See port_range recommendations.
• See num_initial_members recommendations.