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

#!/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"