Tomcat clustering - configuring 2 tomcats on different machines

Question

I'm trying to create a tomcat cluster in order to replicate sessions.

my 2 tomcats are existing on two different machines,

All examples available showed clustering of 2 tomcats on same machine.

Where do i configure the ips of the tomcats in the configuration files?

(currently when i use the default configurations i get the error:"

Oct 30, 2013 10:21:03 AM org.apache.catalina.ha.session.DeltaManager getAllClusterSessions
INFO: Manager [localhost#/HATest]: skipping state transfer. No members active in cluster group."

Thanks!

EDIT: my (default and not so interesting) server.xml:

<?xml version='1.0' encoding='utf-8'?>

  http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
     -->
   <!-- Note:  A "Server" is not itself a "Container", so you may not
   define subcomponents such as "Valves" at this level.
   Documentation at /docs/config/server.html
    -->
  <Server port="8005" shutdown="SHUTDOWN">
  <!-- Security listener. Documentation at /docs/config/listeners.html
 <Listener className="org.apache.catalina.security.SecurityListener" />
   -->

<!--The connectors can use a shared executor, you can define one or more named thread pools-->
<!--
<Executor name="tomcatThreadPool" namePrefix="catalina-exec-"
    maxThreads="150" minSpareThreads="4"/>
-->


<!-- A "Connector" represents an endpoint by which requests are received
     and responses are returned. Documentation at :
     Java HTTP Connector: /docs/config/http.html (blocking & non-blocking)
     Java AJP  Connector: /docs/config/ajp.html
     APR (HTTP/AJP) Connector: /docs/apr.html
     Define a non-SSL HTTP/1.1 Connector on port 8080
-->
<Connector port="8080" protocol="HTTP/1.1"
           connectionTimeout="20000"
           redirectPort="8443" />
<!-- A "Connector" using the shared thread pool-->
<!--
<Connector executor="tomcatThreadPool"
           port="8080" protocol="HTTP/1.1"
           connectionTimeout="20000"
           redirectPort="8443" />
-->
<!-- Define a SSL HTTP/1.1 Connector on port 8443
     This connector uses the JSSE configuration, when using APR, the
     connector should be using the OpenSSL style configuration
     described in the APR documentation -->
<!--
<Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"
           maxThreads="150" scheme="https" secure="true"
           clientAuth="false" sslProtocol="TLS" />
-->

<!-- Define an AJP 1.3 Connector on port 8009 -->
<Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />


<!-- An Engine represents the entry point (within Catalina) that processes
     every request.  The Engine implementation for Tomcat stand alone
     analyzes the HTTP headers included with the request, and passes them
     on to the appropriate Host (virtual host).
     Documentation at /docs/config/engine.html -->

<!-- You should set jvmRoute to support load-balancing via AJP ie :
<Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">
-->
<Engine name="Catalina" defaultHost="localhost">
 <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
  <!--For clustering, please take a look at documentation at:
      /docs/cluster-howto.html  (simple how to)
      /docs/config/cluster.html (reference documentation) -->
  <!--
  <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
  -->

  <!-- Use the LockOutRealm to prevent attempts to guess user passwords
       via a brute-force attack -->
  <Realm className="org.apache.catalina.realm.LockOutRealm">
    <!-- This Realm uses the UserDatabase configured in the global JNDI
         resources under the key "UserDatabase".  Any edits
         that are performed against this UserDatabase are immediately
         available for use by the Realm.  -->
    <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
           resourceName="UserDatabase"/>
  </Realm>

  <Host name="localhost"  appBase="webapps"
        unpackWARs="true" autoDeploy="true">

    <!-- SingleSignOn valve, share authentication between web applications
         Documentation at: /docs/config/valve.html -->
    <!--
    <Valve className="org.apache.catalina.authenticator.SingleSignOn" />
    -->

    <!-- Access log processes all example.
         Documentation at: /docs/config/valve.html
         Note: The pattern used is equivalent to using pattern="common" -->
    <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
           prefix="localhost_access_log." suffix=".txt"
           pattern="%h %l %u %t &quot;%r&quot; %s %b" />

  </Host>
</Engine>

Answer 1

For the default cluster configuration to work between multipl machines, multicast needs to be working. If the nodes can't see each then then the chances are that multicast is not enabled in one or more of the machnes / blocked at the network level / machines are on a different subnet.

In this case, you can use static membership to explicitly define the other machines in the cluster. See the Tomcat clustering docs for details.