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I downloaded mod_cluster native bundles with httpd from http://mod-cluster.jboss.org/mod_cluster/downloads/1-2-6-Final-bin like below. So I did not need to do any configuration for httpd since this tar file contain httpd and related mod_cluster modules.

mod_cluster-1.2.6.Final-linux2-x64.tar.gz

Then I downloaded tomcat7 and do the following two things.

1 . add <Listener className="org.jboss.modcluster.container.catalina.standalone.ModClusterListener" proxyList="192.168.91.128:80" advertise="true"/> to tomcat7/conf/server.xml

2.download mod_cluster-parent-1.2.6.Final-bin.tar.gz from jboss site and extract the jars to tomcat7/lib directory.

I referred all above steps from http://docs.jboss.org/mod_cluster/1.2.0/html/Quick_Start_Guide.html#d0e250.

But after I started up httpd, tomcat7, I found there are error messages in catalina.out generated again and again like below. ERROR: MODCLUSTER000042: Error null sending INFO command to 192.168.91.128/192.168.91.128:80, configuration will be reset: nul

I pasted the critical configuration from httpd.conf.

<IfModule ssl_module>
SSLRandomSeed startup builtin
SSLRandomSeed connect builtin
</IfModule>
<IfModule manager_module>
  Listen 192.168.91.128:6666
  ManagerBalancerName mycluster
  <VirtualHost 192.168.91.128:6666>
    <Location />
     Order deny,allow
     Deny from all
     Allow from 192.168.91
    </Location>

    KeepAliveTimeout 300
    MaxKeepAliveRequests 0
    AdvertiseFrequency 5
    #AdvertiseSecurityKey secret
    #AdvertiseGroup @ADVIP@:23364
    EnableMCPMReceive

    <Location /mod_cluster_manager>
       SetHandler mod_cluster-manager
       Order deny,allow
       Deny from all
       Allow from 192.168.91
    </Location>

  </VirtualHost>
</IfModule>
ServerName localhost
liam xu
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1 Answers1

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Error

Communication between Apache HTTP Server and Tomcat is bidirectional, i.e. Tomcat's mod_cluster library needs to talk to a VirtualHost configured in your Apache HTTP Server -- the exactly one VirtualHost where you have EnableMCPMReceive set. In this case, please, follow Federico's advice and change the proxyList to match your EnableMCPMReceiveVirtualHost IP and port.

Advertising

Furthermore, is it intentional that you use both advertising (Apache HTTP Server using UDP multicast to advertise its presence to Tomcats) and you have proxyList set at the same time? You can get about without one or the other, depending on your desired setup and environment.

Do not use mod_cluster 1.2.6, please

mod_clister 1.2.6 is desperately obsolete; it contains not only severe performance issue but also CVE and several noteworthy bugs. Please, upgrade to mod_cluster 1.3.1.

See http://modcluster.io for 1.3.1.Final release bits or alternatively http://mod-cluster.jboss.org.

Regarding Apache HTTP Server 2.2.x vs 2.4.x

The aforementioned mod_cluster 1.3.1.Final is offered with httpd 2.4.x. Do you have any special desire for older httpd 2.2.x? It is possible to compile mod_cluster 1.3.1 with httpd 2.2.x, it's just not what we do regularly as noted in my comment on the subject.

Happy mod_clustering! K.

Michal Karm Babacek
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