Set up Apache HTTP Server with mod_cluster module to create an intelligent load balancing cluster with JBoss EAP application servers, featuring automatic node discovery, session clustering, and health monitoring.

Prerequisites

Root or sudo access
At least 4GB RAM
Java 11 or higher
Basic understanding of enterprise Java applications
Network connectivity between cluster nodes

What this solves

This tutorial shows how to configure Apache HTTP Server with the mod_cluster module to create an intelligent load balancing solution for JBoss EAP application servers. Unlike traditional load balancers, mod_cluster provides dynamic configuration, automatic node discovery, and context-aware routing based on real-time server metrics.

You'll learn to set up a complete clustering environment with session replication, automatic failover, and comprehensive health monitoring for enterprise Java applications.

Step-by-step installation

Update system packages

Start by updating your system to ensure you have the latest packages and security updates.

sudo apt update && sudo apt upgrade -y

sudo dnf update -y

Install Apache HTTP Server and development tools

Install Apache web server along with development tools needed for compiling mod_cluster from source.

sudo apt install -y apache2 apache2-dev gcc make curl wget unzip
sudo a2enmod ssl
sudo a2enmod headers
sudo a2enmod rewrite

sudo dnf install -y httpd httpd-devel gcc make curl wget unzip
sudo systemctl enable httpd

Download and compile mod_cluster

Download the latest mod_cluster source code and compile it for your Apache installation.

cd /tmp
wget https://github.com/modcluster/mod_cluster/releases/download/2.0.6.Final/mod_cluster-2.0.6.Final-linux-x86_64-ssl.tar.gz
tar -xzf mod_cluster-2.0.6.Final-linux-x86_64-ssl.tar.gz
cd mod_cluster-2.0.6.Final

Install mod_cluster modules

Copy the compiled mod_cluster modules to Apache's modules directory and set proper permissions.

sudo cp so/mod_proxy_cluster.so /usr/lib/apache2/modules/
sudo cp so/mod_cluster_slotmem.so /usr/lib/apache2/modules/
sudo cp so/mod_manager.so /usr/lib/apache2/modules/
sudo cp so/mod_advertise.so /usr/lib/apache2/modules/
sudo chown root:root /usr/lib/apache2/modules/mod_*.so
sudo chmod 644 /usr/lib/apache2/modules/mod_*.so

sudo cp so/mod_proxy_cluster.so /usr/lib64/httpd/modules/
sudo cp so/mod_cluster_slotmem.so /usr/lib64/httpd/modules/
sudo cp so/mod_manager.so /usr/lib64/httpd/modules/
sudo cp so/mod_advertise.so /usr/lib64/httpd/modules/
sudo chown root:root /usr/lib64/httpd/modules/mod_*.so
sudo chmod 644 /usr/lib64/httpd/modules/mod_*.so

Configure mod_cluster in Apache

Create the mod_cluster configuration file to define cluster behavior and load balancing parameters.

LoadModule cluster_slotmem_module modules/mod_cluster_slotmem.so
LoadModule manager_module modules/mod_manager.so
LoadModule proxy_cluster_module modules/mod_proxy_cluster.so
LoadModule advertise_module modules/mod_advertise.so

sudo a2enmod cluster

LoadModule cluster_slotmem_module modules/mod_cluster_slotmem.so
LoadModule manager_module modules/mod_manager.so
LoadModule proxy_cluster_module modules/mod_proxy_cluster.so
LoadModule advertise_module modules/mod_advertise.so

Create mod_cluster virtual host configuration

Configure a dedicated virtual host for mod_cluster management and load balancing operations.


    ServerName cluster-manager.example.com
    
    # Enable mod_cluster manager
    
        SetHandler mod_cluster-manager
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    
    
    # Configure mod_cluster parameters
    CreateBalancers 1
    ProxyPreserveHost On
    ManagerBalancerName mycluster
    
    # Health checking
    PingMode 1
    PingTimeout 10
    
    # Session stickiness
    UseAlias 1
    
    # Advertising configuration
    ServerAdvertise On
    AdvertiseFrequency 5
    AdvertiseBindAddress 224.0.1.105:23364
    
    # Allow connections from JBoss nodes
    
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    
    
    # Error and access logs
    ErrorLog ${APACHE_LOG_DIR}/mod_cluster_error.log
    CustomLog ${APACHE_LOG_DIR}/mod_cluster_access.log combined

sudo a2ensite mod-cluster
sudo a2dissite 000-default


    ServerName cluster-manager.example.com
    
    # Enable mod_cluster manager
    
        SetHandler mod_cluster-manager
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    
    
    # Configure mod_cluster parameters
    CreateBalancers 1
    ProxyPreserveHost On
    ManagerBalancerName mycluster
    
    # Health checking
    PingMode 1
    PingTimeout 10
    
    # Session stickiness
    UseAlias 1
    
    # Advertising configuration
    ServerAdvertise On
    AdvertiseFrequency 5
    AdvertiseBindAddress 224.0.1.105:23364
    
    # Allow connections from JBoss nodes
    
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    
    
    # Error and access logs
    ErrorLog /var/log/httpd/mod_cluster_error.log
    CustomLog /var/log/httpd/mod_cluster_access.log combined

Install JBoss EAP

Download and install JBoss EAP application server which will serve as cluster nodes.

cd /opt
sudo wget https://developers.redhat.com/download-manager/file/jboss-eap-8.0.0.zip
sudo unzip jboss-eap-8.0.0.zip
sudo mv jboss-eap-8.0 jboss-eap
sudo chown -R jboss:jboss /opt/jboss-eap

Create JBoss user and group

Create a dedicated system user for running JBoss EAP securely without root privileges.

sudo groupadd -r jboss
sudo useradd -r -g jboss -d /opt/jboss-eap -s /bin/bash jboss
sudo chown -R jboss:jboss /opt/jboss-eap

Configure JBoss EAP for clustering

Create a clustered configuration for JBoss EAP with mod_cluster connector enabled.

Create systemd service for JBoss EAP cluster nodes

Create systemd service files for running multiple JBoss EAP instances as cluster nodes.

[Unit]
Description=JBoss EAP Node 1
After=network.target

[Service]
Type=simple
User=jboss
Group=jboss
ExecStart=/opt/jboss-eap/bin/standalone.sh -c standalone-ha-mod-cluster.xml -Djboss.bind.address=0.0.0.0 -Djboss.bind.address.management=0.0.0.0 -Djboss.node.name=node1 -Djboss.socket.binding.port-offset=0
ExecStop=/bin/kill -TERM $MAINPID
Restart=always
RestartSec=10
Environment=JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
Environment=JBOSS_HOME=/opt/jboss-eap
WorkingDirectory=/opt/jboss-eap

[Install]
WantedBy=multi-user.target

[Unit]
Description=JBoss EAP Node 2
After=network.target

[Service]
Type=simple
User=jboss
Group=jboss
ExecStart=/opt/jboss-eap/bin/standalone.sh -c standalone-ha-mod-cluster.xml -Djboss.bind.address=0.0.0.0 -Djboss.bind.address.management=0.0.0.0 -Djboss.node.name=node2 -Djboss.socket.binding.port-offset=100
ExecStop=/bin/kill -TERM $MAINPID
Restart=always
RestartSec=10
Environment=JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
Environment=JBOSS_HOME=/opt/jboss-eap
WorkingDirectory=/opt/jboss-eap

[Install]
WantedBy=multi-user.target

sudo systemctl daemon-reload

Install Java Development Kit

Install OpenJDK which is required for running JBoss EAP application server.

sudo apt install -y openjdk-11-jdk
export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
echo 'export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64' | sudo tee -a /etc/environment

sudo dnf install -y java-11-openjdk-devel
export JAVA_HOME=/usr/lib/jvm/java-11-openjdk
echo 'export JAVA_HOME=/usr/lib/jvm/java-11-openjdk' | sudo tee -a /etc/environment

Configure firewall rules

Open necessary ports for cluster communication, web traffic, and management interfaces.

sudo ufw allow 80/tcp
sudo ufw allow 443/tcp
sudo ufw allow 8080/tcp
sudo ufw allow 8180/tcp
sudo ufw allow 8009/tcp
sudo ufw allow 8109/tcp
sudo ufw allow 9990/tcp
sudo ufw allow 10090/tcp
sudo ufw allow 7600/tcp
sudo ufw allow 7700/tcp
sudo ufw allow 55200/udp
sudo ufw allow 55300/udp
sudo ufw allow 45688/udp
sudo ufw allow 45788/udp
sudo ufw allow 23364/udp
sudo ufw --force enable

sudo firewall-cmd --permanent --add-port=80/tcp
sudo firewall-cmd --permanent --add-port=443/tcp
sudo firewall-cmd --permanent --add-port=8080/tcp
sudo firewall-cmd --permanent --add-port=8180/tcp
sudo firewall-cmd --permanent --add-port=8009/tcp
sudo firewall-cmd --permanent --add-port=8109/tcp
sudo firewall-cmd --permanent --add-port=9990/tcp
sudo firewall-cmd --permanent --add-port=10090/tcp
sudo firewall-cmd --permanent --add-port=7600/tcp
sudo firewall-cmd --permanent --add-port=7700/tcp
sudo firewall-cmd --permanent --add-port=55200/udp
sudo firewall-cmd --permanent --add-port=55300/udp
sudo firewall-cmd --permanent --add-port=45688/udp
sudo firewall-cmd --permanent --add-port=45788/udp
sudo firewall-cmd --permanent --add-port=23364/udp
sudo firewall-cmd --reload

Start all services

Enable and start Apache HTTP Server and both JBoss EAP cluster nodes.

sudo systemctl enable apache2
sudo systemctl start apache2
sudo systemctl enable jboss-node1
sudo systemctl start jboss-node1
sudo systemctl enable jboss-node2
sudo systemctl start jboss-node2

sudo systemctl enable httpd
sudo systemctl start httpd
sudo systemctl enable jboss-node1
sudo systemctl start jboss-node1
sudo systemctl enable jboss-node2
sudo systemctl start jboss-node2

Create a sample clustered application

Deploy a simple web application that demonstrates session clustering and failover capabilities.



    
    Cluster Test Application

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ page import="java.util.Date" %>
<%@ page import="java.net.InetAddress" %>



    Cluster Test Application
    


    JBoss EAP Cluster Test
    
    
        Server Information
        Server: <%= InetAddress.getLocalHost().getHostName() %>

        Node Name: <%= System.getProperty("jboss.node.name") %>

        Current Time: <%= new Date() %>

        Session ID: <%= session.getId() %>

    
    
    <%
        String visitCount = (String) session.getAttribute("visitCount");
        if (visitCount == null) {
            visitCount = "1";
        } else {
            visitCount = String.valueOf(Integer.parseInt(visitCount) + 1);
        }
        session.setAttribute("visitCount", visitCount);
        session.setAttribute("lastVisit", new Date().toString());
    %>
    
    
        Session Information
        Visit Count: <%= visitCount %>

        Last Visit: <%= session.getAttribute("lastVisit") %>

        Session Created: <%= new Date(session.getCreationTime()) %>

        Max Inactive Interval: <%= session.getMaxInactiveInterval() %> seconds

    
    
    Refresh Page
    Invalidate Session

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>



    Session Invalidated
    


    Session Invalidated
    
    <%
        session.invalidate();
    %>
    
    
        Your session has been invalidated. Click the link below to start a new session.
    
    
    Start New Session

sudo mkdir -p /opt/jboss-eap/standalone/deployments/cluster-test.war/WEB-INF
sudo chown -R jboss:jboss /opt/jboss-eap/standalone/deployments/cluster-test.war

Configure session clustering and failover

Enable session replication

Configure both JBoss nodes to replicate session data for seamless failover between cluster nodes.



    
    
        SESSION
        SET_AND_NON_PRIMITIVE_GET

Configure health monitoring

Set up comprehensive health checks and monitoring for the cluster nodes and load balancer.

<%@ page language="java" contentType="text/plain; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ page import="java.sql.*" %>
<%@ page import="javax.naming.*" %>
<%
    response.setContentType("text/plain");
    
    try {
        // Basic health check
        String nodeName = System.getProperty("jboss.node.name", "unknown");
        long freeMemory = Runtime.getRuntime().freeMemory();
        long totalMemory = Runtime.getRuntime().totalMemory();
        long usedMemory = totalMemory - freeMemory;
        double memoryUsage = (double) usedMemory / totalMemory * 100;
        
        if (memoryUsage < 90) {
            response.setStatus(200);
            out.println("OK - Node: " + nodeName + ", Memory Usage: " + String.format("%.2f", memoryUsage) + "%");
        } else {
            response.setStatus(503);
            out.println("ERROR - High memory usage: " + String.format("%.2f", memoryUsage) + "%");
        }
    } catch (Exception e) {
        response.setStatus(503);
        out.println("ERROR - " + e.getMessage());
    }
%>

Configure automatic node discovery

Enable multicast advertising

Configure automatic node discovery using multicast advertising so new nodes automatically join the cluster.

# Enable IP forwarding for multicast
net.ipv4.ip_forward = 1

Increase multicast buffer sizes
net.core.rmem_default = 262144
net.core.rmem_max = 16777216
net.core.wmem_default = 262144
net.core.wmem_max = 16777216

Allow multicast
net.ipv4.conf.all.mc_forwarding = 1

sudo sysctl -p /etc/sysctl.d/99-multicast.conf

Restart services and test discovery

Restart all services to apply configuration changes and verify automatic node discovery is working.

sudo systemctl restart apache2
sudo systemctl restart jboss-node1
sudo systemctl restart jboss-node2

sudo systemctl restart httpd
sudo systemctl restart jboss-node1
sudo systemctl restart jboss-node2

Performance optimization and monitoring

Optimize Apache for clustering

Configure Apache performance settings specifically optimized for cluster traffic and high availability.

# Add these lines to optimize for clustering

Increase worker limits for cluster traffic
ServerLimit 16
MaxRequestWorkers 400
ThreadsPerChild 25

Connection pooling for backend servers
ProxyIOBufferSize 65536
ProxyReceiveBufferSize 262144

Enable persistent connections
ProxyPreserveHost On
ProxyAddHeaders On

Timeout settings for cluster health
ProxyTimeout 30
ProxyConnectTimeout 5

Enable status monitoring
ExtendedStatus On

# Add these lines to optimize for clustering

Increase worker limits for cluster traffic
ServerLimit 16
MaxRequestWorkers 400
ThreadsPerChild 25

Connection pooling for backend servers
ProxyIOBufferSize 65536
ProxyReceiveBufferSize 262144

Enable persistent connections
ProxyPreserveHost On
ProxyAddHeaders On

Timeout settings for cluster health
ProxyTimeout 30
ProxyConnectTimeout 5

Enable status monitoring
ExtendedStatus On

Configure monitoring endpoints

Set up monitoring endpoints to track cluster health, performance metrics, and node status.


    ServerName monitoring.example.com
    
    # Apache server status
    
        SetHandler server-status
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    
    
    # Apache server info
    
        SetHandler server-info
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    
    
    # Mod_cluster status
    
        ProxyPass http://localhost/mod_cluster_manager
        ProxyPassReverse http://localhost/mod_cluster_manager
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    
    
    ErrorLog ${APACHE_LOG_DIR}/monitoring_error.log
    CustomLog ${APACHE_LOG_DIR}/monitoring_access.log combined


Listen on port 8081 for monitoring
Listen 8081

sudo a2ensite monitoring
sudo a2enmod status
sudo a2enmod info


    ServerName monitoring.example.com
    
    # Apache server status
    
        SetHandler server-status
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    
    
    # Apache server info
    
        SetHandler server-info
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    
    
    # Mod_cluster status
    
        ProxyPass http://localhost/mod_cluster_manager
        ProxyPassReverse http://localhost/mod_cluster_manager
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    
    
    ErrorLog /var/log/httpd/monitoring_error.log
    CustomLog /var/log/httpd/monitoring_access.log combined


Listen on port 8081 for monitoring
Listen 8081

Final service restart

Restart Apache to apply all configuration changes and complete the cluster setup.

sudo systemctl reload apache2

sudo systemctl reload httpd

Verify your setup

# Check Apache status
sudo systemctl status apache2  # or httpd on RHEL-based systems

Check JBoss cluster nodes
sudo systemctl status jboss-node1
sudo systemctl status jboss-node2

Test mod_cluster manager interface
curl -s http://localhost/mod_cluster_manager

Test cluster application
curl -s http://localhost:8080/cluster-test/ | grep "Visit Count"

Check cluster node registration
curl -s http://localhost/mod_cluster_manager | grep -A 5 "Balancer"

Test session stickiness
curl -c cookies.txt -b cookies.txt http://localhost:8080/cluster-test/
curl -c cookies.txt -b cookies.txt http://localhost:8080/cluster-test/

Check health endpoints
curl -s http://localhost:8080/cluster-test/health.jsp
curl -s http://localhost:8180/cluster-test/health.jsp

Monitor Apache server status
curl -s http://localhost:8081/server-status?auto

Check cluster member discovery
grep -i "cluster" /opt/jboss-eap/standalone/log/server.log | tail -10

Note: The cluster may take 30-60 seconds to fully initialize after starting services. Node discovery and registration with mod_cluster happens automatically via multicast advertising.

Testing session failover

To test session clustering and failover capabilities, you can simulate node failures and verify that sessions are preserved across cluster nodes. This is essential for ensuring high availability in production environments.

# Start a session on node 1
curl -c session.txt http://localhost:8080/cluster-test/

Stop node 1 to simulate failure
sudo systemctl stop jboss-node1

Continue session on node 2 (should preserve session data)
curl -b session.txt http://localhost:8080/cluster-test/

Restart node 1
sudo systemctl start jboss-node1

Verify node rejoins cluster
curl -s http://localhost/mod_cluster_manager | grep node1

Load balancing verification

Test that mod_cluster properly distributes requests across available nodes based on server metrics and health status.

# Create test script for load distribution
cat > test_load_balancing.sh << 'EOF'
#!/bin/bash

echo "Testing load distribution across cluster nodes..."

for i in {1..20}; do
    response=$(curl -s http://localhost:8080/cluster-test/ | grep "Node Name")
    echo "Request $i: $response"
    sleep 1
done
EOF

chmod +x test_load_balancing.sh
./test_load_balancing.sh

Common issues

Symptom	Cause	Fix
Nodes not registering with mod_cluster	Multicast not working or firewall blocking	Check `sudo netstat -tulpn \| grep 23364` and verify firewall rules
Session data not replicating	Missing `<distributable/>` in web.xml	Add distributable element to web application descriptor
High memory usage on cluster nodes	Session replication overhead	Tune JVM heap size: `-Xmx2g -Xms1g` in service file
Load balancer not detecting failed nodes	Health check timeout too long	Reduce `PingTimeout` in mod_cluster configuration
Apache returns 503 Service Unavailable	No healthy backend nodes available	Check JBoss logs: `tail -f /opt/jboss-eap/standalone/log/server.log`
Cluster nodes can't communicate	JGroups configuration issues	Verify multicast connectivity: `sudo tcpdump -i any host 230.0.0.4`

Security Warning: Never use the management interfaces in production without proper authentication. The configurations shown here are for development and testing only. Always implement SSL/TLS, strong authentication, and network access controls for production deployments.

Next steps

Configure Apache HTTP/2 with performance optimization for modern protocol support
Setup nginx reverse proxy with SSL certificates for alternative load balancing approaches
Configure Linux system performance monitoring for comprehensive cluster monitoring
Implement HAProxy SSL termination with Let's Encrypt certificates for SSL offloading
Configure JBoss EAP SSL certificates and security hardening for production security

Running this in production?

Want this handled for you? Running enterprise Java clustering at scale adds a second layer of work: capacity planning, security hardening, backup strategies, and 24/7 monitoring. See how we run infrastructure like this for European SaaS and enterprise teams.

Automated install script

Run this to automate the entire setup

install.sh

#!/usr/bin/env bash
set -euo pipefail

# Apache mod_cluster installation and configuration script
# Supports Ubuntu, Debian, AlmaLinux, Rocky Linux, CentOS, RHEL

# Color definitions
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m'

# Configuration variables
CLUSTER_DOMAIN="${1:-cluster-manager.example.com}"
MOD_CLUSTER_VERSION="2.0.6.Final"
TEMP_DIR="/tmp/mod_cluster_install"

# Print colored output
log_info() { echo -e "${GREEN}[INFO]${NC} $1"; }
log_warn() { echo -e "${YELLOW}[WARN]${NC} $1"; }
log_error() { echo -e "${RED}[ERROR]${NC} $1"; }

# Usage function
usage() {
    echo "Usage: $0 [cluster-domain]"
    echo "Example: $0 cluster-manager.example.com"
    exit 1
}

# Cleanup function
cleanup() {
    log_warn "Cleaning up temporary files..."
    rm -rf "$TEMP_DIR"
}

# Error handler
error_handler() {
    log_error "Script failed on line $1"
    cleanup
    exit 1
}

trap 'error_handler $LINENO' ERR
trap cleanup EXIT

# Check if running as root
if [[ $EUID -ne 0 ]]; then
    log_error "This script must be run as root or with sudo"
    exit 1
fi

# Auto-detect distribution
if [ -f /etc/os-release ]; then
    . /etc/os-release
    case "$ID" in
        ubuntu|debian)
            PKG_MGR="apt"
            PKG_INSTALL="apt install -y"
            PKG_UPDATE="apt update && apt upgrade -y"
            APACHE_SERVICE="apache2"
            APACHE_MODULES_DIR="/usr/lib/apache2/modules"
            APACHE_CONFIG_DIR="/etc/apache2"
            APACHE_SITES_DIR="/etc/apache2/sites-available"
            APACHE_LOG_VAR="\${APACHE_LOG_DIR}"
            ;;
        almalinux|rocky|centos|rhel|ol|fedora)
            PKG_MGR="dnf"
            PKG_INSTALL="dnf install -y"
            PKG_UPDATE="dnf update -y"
            APACHE_SERVICE="httpd"
            APACHE_MODULES_DIR="/usr/lib64/httpd/modules"
            APACHE_CONFIG_DIR="/etc/httpd"
            APACHE_SITES_DIR="/etc/httpd/conf.d"
            APACHE_LOG_VAR="logs"
            ;;
        amzn)
            PKG_MGR="yum"
            PKG_INSTALL="yum install -y"
            PKG_UPDATE="yum update -y"
            APACHE_SERVICE="httpd"
            APACHE_MODULES_DIR="/usr/lib64/httpd/modules"
            APACHE_CONFIG_DIR="/etc/httpd"
            APACHE_SITES_DIR="/etc/httpd/conf.d"
            APACHE_LOG_VAR="logs"
            ;;
        *)
            log_error "Unsupported distribution: $ID"
            exit 1
            ;;
    esac
else
    log_error "Cannot detect distribution (/etc/os-release not found)"
    exit 1
fi

log_info "Detected distribution: $PRETTY_NAME"
log_info "Installing Apache mod_cluster for domain: $CLUSTER_DOMAIN"

echo "[1/8] Updating system packages..."
$PKG_UPDATE

echo "[2/8] Installing Apache and development tools..."
case "$PKG_MGR" in
    apt)
        $PKG_INSTALL apache2 apache2-dev gcc make curl wget unzip
        a2enmod ssl
        a2enmod headers
        a2enmod rewrite
        ;;
    dnf|yum)
        $PKG_INSTALL httpd httpd-devel gcc make curl wget unzip
        systemctl enable httpd
        ;;
esac

echo "[3/8] Creating temporary directory and downloading mod_cluster..."
mkdir -p "$TEMP_DIR"
cd "$TEMP_DIR"
wget "https://github.com/modcluster/mod_cluster/releases/download/${MOD_CLUSTER_VERSION}/mod_cluster-${MOD_CLUSTER_VERSION}-linux-x86_64-ssl.tar.gz"
tar -xzf "mod_cluster-${MOD_CLUSTER_VERSION}-linux-x86_64-ssl.tar.gz"
cd "mod_cluster-${MOD_CLUSTER_VERSION}"

echo "[4/8] Installing mod_cluster modules..."
cp so/mod_proxy_cluster.so "$APACHE_MODULES_DIR/"
cp so/mod_cluster_slotmem.so "$APACHE_MODULES_DIR/"
cp so/mod_manager.so "$APACHE_MODULES_DIR/"
cp so/mod_advertise.so "$APACHE_MODULES_DIR/"
chown root:root "$APACHE_MODULES_DIR"/mod_*.so
chmod 644 "$APACHE_MODULES_DIR"/mod_*.so

echo "[5/8] Configuring mod_cluster modules..."
case "$PKG_MGR" in
    apt)
        cat > "$APACHE_CONFIG_DIR/mods-available/cluster.load" << 'EOF'
LoadModule cluster_slotmem_module modules/mod_cluster_slotmem.so
LoadModule manager_module modules/mod_manager.so
LoadModule proxy_cluster_module modules/mod_proxy_cluster.so
LoadModule advertise_module modules/mod_advertise.so
EOF
        a2enmod cluster
        ;;
    dnf|yum)
        cat >> "$APACHE_CONFIG_DIR/conf.modules.d/00-cluster.conf" << 'EOF'
LoadModule cluster_slotmem_module modules/mod_cluster_slotmem.so
LoadModule manager_module modules/mod_manager.so
LoadModule proxy_cluster_module modules/mod_proxy_cluster.so
LoadModule advertise_module modules/mod_advertise.so
EOF
        ;;
esac

echo "[6/8] Creating mod_cluster virtual host configuration..."
case "$PKG_MGR" in
    apt)
        CONFIG_FILE="$APACHE_SITES_DIR/mod-cluster.conf"
        ;;
    dnf|yum)
        CONFIG_FILE="$APACHE_SITES_DIR/mod-cluster.conf"
        ;;
esac

cat > "$CONFIG_FILE" << EOF
<VirtualHost *:80>
    ServerName $CLUSTER_DOMAIN
    
    # Enable mod_cluster manager
    <Location /mod_cluster_manager>
        SetHandler mod_cluster-manager
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    </Location>
    
    # Configure mod_cluster parameters
    CreateBalancers 1
    ProxyPreserveHost On
    ManagerBalancerName mycluster
    
    # Health checking
    PingMode 1
    PingTimeout 10
    
    # Session stickiness
    UseAlias 1
    
    # Advertising configuration
    ServerAdvertise On
    AdvertiseFrequency 5
    AdvertiseBindAddress 224.0.1.105:23364
    
    # Allow connections from JBoss nodes
    <Location />
        Require ip 127.0.0.1
        Require ip 10.0.0.0/24
    </Location>
    
    # Error and access logs
    ErrorLog $APACHE_LOG_VAR/mod_cluster_error.log
    CustomLog $APACHE_LOG_VAR/mod_cluster_access.log combined
</VirtualHost>
EOF

chmod 644 "$CONFIG_FILE"

case "$PKG_MGR" in
    apt)
        a2ensite mod-cluster
        a2dissite 000-default || true
        ;;
esac

echo "[7/8] Configuring firewall and starting services..."
case "$PKG_MGR" in
    apt)
        if command -v ufw >/dev/null 2>&1; then
            ufw --force enable
            ufw allow 80/tcp
            ufw allow 23364/udp
        fi
        systemctl restart apache2
        systemctl enable apache2
        ;;
    dnf|yum)
        if command -v firewall-cmd >/dev/null 2>&1; then
            systemctl enable --now firewalld
            firewall-cmd --permanent --add-service=http
            firewall-cmd --permanent --add-port=23364/udp
            firewall-cmd --reload
        fi
        systemctl restart httpd
        systemctl enable httpd
        ;;
esac

# SELinux configuration for RHEL-based systems
if command -v setsebool >/dev/null 2>&1; then
    setsebool -P httpd_can_network_connect 1
fi

echo "[8/8] Verifying installation..."
sleep 3

if systemctl is-active --quiet "$APACHE_SERVICE"; then
    log_info "Apache service is running"
else
    log_error "Apache service failed to start"
    exit 1
fi

if curl -sf "http://localhost/mod_cluster_manager" >/dev/null 2>&1; then
    log_info "mod_cluster manager is accessible"
else
    log_warn "mod_cluster manager may not be accessible (this is normal if not accessing from allowed IPs)"
fi

log_info "Installation completed successfully!"
log_info "Access mod_cluster manager at: http://$CLUSTER_DOMAIN/mod_cluster_manager"
log_info "Configure your JBoss EAP instances to connect to this cluster manager"
log_info "Remember to update IP restrictions in $CONFIG_FILE as needed"

Review the script before running. Execute with: bash install.sh

#apache #mod_cluster #jboss #clustering #load-balancing

Configure Apache HTTP Server clustering with mod_cluster and JBoss EAP for enterprise load balancing

Prerequisites

What this solves

Step-by-step installation

Update system packages

Install Apache HTTP Server and development tools

Download and compile mod_cluster

Install mod_cluster modules

Configure mod_cluster in Apache

Create mod_cluster virtual host configuration

Install JBoss EAP

Create JBoss user and group

Configure JBoss EAP for clustering

Create systemd service for JBoss EAP cluster nodes

Install Java Development Kit

Configure firewall rules

Start all services

Create a sample clustered application

JBoss EAP Cluster Test

Server Information

Session Information

Session Invalidated

Configure session clustering and failover

Enable session replication

Configure health monitoring

Configure automatic node discovery

Enable multicast advertising

Increase multicast buffer sizes

Allow multicast

Restart services and test discovery

Performance optimization and monitoring

Optimize Apache for clustering

Increase worker limits for cluster traffic

Connection pooling for backend servers

Enable persistent connections

Timeout settings for cluster health

Enable status monitoring

Increase worker limits for cluster traffic

Connection pooling for backend servers

Enable persistent connections

Timeout settings for cluster health

Enable status monitoring

Configure monitoring endpoints

Listen on port 8081 for monitoring

Listen on port 8081 for monitoring

Final service restart

Verify your setup

Check JBoss cluster nodes

Test mod_cluster manager interface

Test cluster application

Check cluster node registration

Test session stickiness

Check health endpoints

Monitor Apache server status

Check cluster member discovery

Testing session failover

Stop node 1 to simulate failure

Continue session on node 2 (should preserve session data)

Restart node 1

Verify node rejoins cluster

Load balancing verification

Common issues

Next steps

Running this in production?

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