Error MEM sending STATUS command to <host>, configuration will be reset: MEM: Can't read node
I'm trying to implement Wildfly 8.1.0.Final domain setup, profile full-ha, with 1 master and 2 slaves with load balancing by mod_cluster.
My environment: 1) host master on VPS (DigitalOCean) Ubuntu 14.04 LTS x64, Wildfly 8.1.0.Final and Apache Web Server 2.4.7 with mod_cluster 1.3.1.Alpha3-SNAPSHOT; 2) host slave1 on VPS (DigitalOCean) Ubuntu 14.04 LTS x64 and Wildfly 8.1.0.Final; 3) host slave2 on VPS (DigitalOCean) Ubuntu 14.04 LTS x64 and Wildfly 8.1.0.Final.
I had to compile mod_cluster due incompatibility of version 1.2.6 with Apache Web Server 2.4.7.
I see the following errors:
a) on host master (/var/log/apache2/error.log): "(111)Connection refused: AH00957: ajp: attempt to connect to host_slave1 failed"
b) on host slave1 (/opt/wildfly/domain/configuration/servers/server-one/server.log): "2014-09-18 20:50:55,169 ERROR [org.jboss.modcluster] (UndertowEventHandlerAdapter - 1) MODCLUSTER000042: Error MEM sending STATUS command to host_master, configuration will be reset: MEM: Can't read node"
So the load balancing virtual host with mod_cluster is unable to connect to hosts slave1 and slave2.
How to solve this issue, please?
Answer
At first, you could use mod_cluster 1.3.1.Final now that is fully integrated with Apache HTTP Server 2.4.x.
The answer
The problem is definitely in you network/host isolation. It is not enough that your worker node can access the EnableMCPMReceive enabled VirtualHost; your Apache HTTP Server must be able to reach back to the worker.
Take a look at the IP address (hostname) the host_slave1 reported to the Apache HTTP Server and make sure it is possible to contact the host_slave1 on that address:port from the Apache HTTP Server machine.
One may easily verify the status on Mod_cluster maanger console, enabled in a virtual host with:
<Location /mod_cluster_manager>
SetHandler mod_cluster-manager
# This is super sensitive, don't open to the world...
Require ip 127.0.0.1
</Location>
HTH