There are a couple of tools that can be used to manage and retrieve runtime information from your cluster. Your first option is the command-line management interface, which allows you to investigate the mod_cluster subsystem.

The first command you need to learn is list-proxies, which returns merely the hostnames (and port) of the connected proxies:

[domain@localhost:9990 /] /host=master/server=server-one/subsystem=modcluster:list-proxies
{
    "outcome" => "success",
    "result" => ["apache-wildfly:6666"]
}

While this can be useful for a quick inspection of your cluster members, you can get more detailed information with the read-proxies-info command that actually sends an information message to the HTTPD server:

[domain@localhost:9990 /] /host=master/server=server-one/subsystem=modcluster:read-proxies-info
{
    "outcome" => "success",
    "result" => [
        "apache-wildfly:6666",
        "Node: [1],Name: master:server-two,Balancer: mycluster...