Fix Apache web server high memory usage and optimize performance

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

# Apache Memory Optimization Script
# Optimizes Apache web server for better memory usage and performance

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

# Global variables
APACHE_SERVICE=""
APACHE_CTL=""
APACHE_CONF_DIR=""
SITES_DIR=""
MODS_DIR=""
BACKUP_DIR="/tmp/apache_optimization_backup_$(date +%Y%m%d_%H%M%S)"

# Usage function
usage() {
    echo "Usage: $0 [OPTIONS]"
    echo "Options:"
    echo "  -m, --max-workers NUM    Set MaxRequestWorkers (default: auto-calculate)"
    echo "  -h, --help              Show this help message"
    exit 1
}

# Error handling
cleanup() {
    if [[ $? -ne 0 ]]; then
        echo -e "${RED}[ERROR] Script failed. Restoring backup from $BACKUP_DIR${NC}"
        if [[ -d "$BACKUP_DIR" ]]; then
            cp -r "$BACKUP_DIR"/* "$APACHE_CONF_DIR"/ 2>/dev/null || true
            systemctl reload "$APACHE_SERVICE" 2>/dev/null || true
        fi
    fi
}
trap cleanup ERR

# Logging functions
log_info() { echo -e "${GREEN}$1${NC}"; }
log_warn() { echo -e "${YELLOW}$1${NC}"; }
log_error() { echo -e "${RED}$1${NC}"; }

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

# Detect distribution and set package manager
detect_distro() {
    if [[ ! -f /etc/os-release ]]; then
        log_error "Cannot detect distribution. /etc/os-release not found."
        exit 1
    fi
    
    . /etc/os-release
    case "$ID" in
        ubuntu|debian)
            PKG_MGR="apt"
            PKG_INSTALL="apt install -y"
            PKG_UPDATE="apt update"
            APACHE_SERVICE="apache2"
            APACHE_CTL="apache2ctl"
            APACHE_CONF_DIR="/etc/apache2"
            SITES_DIR="/etc/apache2/sites-available"
            MODS_DIR="/etc/apache2/mods-available"
            ;;
        almalinux|rocky|centos|rhel|ol|fedora)
            PKG_MGR="dnf"
            PKG_INSTALL="dnf install -y"
            PKG_UPDATE="dnf check-update"
            APACHE_SERVICE="httpd"
            APACHE_CTL="httpd"
            APACHE_CONF_DIR="/etc/httpd"
            SITES_DIR="/etc/httpd/conf.d"
            MODS_DIR="/etc/httpd/conf.modules.d"
            ;;
        amzn)
            PKG_MGR="yum"
            PKG_INSTALL="yum install -y"
            PKG_UPDATE="yum check-update"
            APACHE_SERVICE="httpd"
            APACHE_CTL="httpd"
            APACHE_CONF_DIR="/etc/httpd"
            SITES_DIR="/etc/httpd/conf.d"
            MODS_DIR="/etc/httpd/conf.modules.d"
            ;;
        *)
            log_error "Unsupported distribution: $ID"
            exit 1
            ;;
    esac
}

# Create backup
create_backup() {
    log_info "[2/8] Creating configuration backup..."
    mkdir -p "$BACKUP_DIR"
    cp -r "$APACHE_CONF_DIR"/* "$BACKUP_DIR"/
    log_info "Backup created at $BACKUP_DIR"
}

# Install required packages
install_packages() {
    log_info "[3/8] Installing required packages..."
    $PKG_UPDATE >/dev/null 2>&1 || true
    
    if [[ "$PKG_MGR" == "apt" ]]; then
        $PKG_INSTALL htop procps >/dev/null
    else
        $PKG_INSTALL htop procps-ng >/dev/null
        if ! command -v httpd >/dev/null; then
            $PKG_INSTALL httpd httpd-devel >/dev/null
        fi
    fi
}

# Calculate optimal MaxRequestWorkers
calculate_max_workers() {
    local total_mem=$(free -m | awk '/^Mem:/{print $2}')
    local available_mem=$((total_mem * 3 / 4))
    local avg_process_size=25
    echo $((available_mem / avg_process_size))
}

# Configure Event MPM
configure_event_mpm() {
    log_info "[4/8] Configuring Event MPM module..."
    
    local max_workers=${MAX_WORKERS:-$(calculate_max_workers)}
    local server_limit=$((max_workers / 25 + 1))
    
    if [[ "$PKG_MGR" == "apt" ]]; then
        # Disable prefork, enable event
        a2dismod mpm_prefork >/dev/null 2>&1 || true
        a2enmod mpm_event >/dev/null 2>&1
        
        # Configure Event MPM
        cat > "$APACHE_CONF_DIR/mods-available/mpm_event.conf" << EOF
<IfModule mpm_event_module>
    StartServers             3
    MinSpareThreads          25
    MaxSpareThreads          75
    ThreadLimit              64
    ThreadsPerChild          25
    MaxRequestWorkers        $max_workers
    ServerLimit              $server_limit
    AsyncRequestWorkerFactor 2
</IfModule>
EOF
    else
        # RHEL-based systems
        sed -i 's/^LoadModule mpm_prefork_module/#LoadModule mpm_prefork_module/' "$MODS_DIR/00-mpm.conf" 2>/dev/null || true
        sed -i 's/^#LoadModule mpm_event_module/LoadModule mpm_event_module/' "$MODS_DIR/00-mpm.conf" 2>/dev/null || true
        
        cat > "$APACHE_CONF_DIR/conf.d/mpm_event.conf" << EOF
<IfModule mpm_event_module>
    StartServers             3
    MinSpareThreads          25
    MaxSpareThreads          75
    ThreadLimit              64
    ThreadsPerChild          25
    MaxRequestWorkers        $max_workers
    ServerLimit              $server_limit
    AsyncRequestWorkerFactor 2
</IfModule>
EOF
    fi
    
    log_info "Event MPM configured with MaxRequestWorkers: $max_workers"
}

# Disable unnecessary modules
disable_modules() {
    log_info "[5/8] Disabling unnecessary modules..."
    
    local modules_to_disable=("status" "autoindex" "negotiation" "include")
    
    if [[ "$PKG_MGR" == "apt" ]]; then
        for module in "${modules_to_disable[@]}"; do
            a2dismod "$module" >/dev/null 2>&1 || true
        done
    else
        # Comment out modules in RHEL-based systems
        for module in "${modules_to_disable[@]}"; do
            sed -i "s/^LoadModule ${module}_module/#LoadModule ${module}_module/" "$MODS_DIR"/*.conf 2>/dev/null || true
        done
    fi
}

# Optimize Apache configuration
optimize_apache_config() {
    log_info "[6/8] Optimizing Apache configuration..."
    
    local config_file=""
    if [[ "$PKG_MGR" == "apt" ]]; then
        config_file="$APACHE_CONF_DIR/apache2.conf"
    else
        config_file="$APACHE_CONF_DIR/conf/httpd.conf"
    fi
    
    # Add optimization settings
    cat >> "$config_file" << EOF

# Memory and Performance Optimizations
KeepAlive On
MaxKeepAliveRequests 100
KeepAliveTimeout 5

# Security and Performance Headers
ServerTokens Prod
ServerSignature Off

# Timeout Settings
Timeout 60
RequestReadTimeout 60

# Limit request size (adjust as needed)
LimitRequestBody 10485760
EOF
    
    # Set proper permissions
    chown root:root "$config_file"
    chmod 644 "$config_file"
}

# Setup monitoring
setup_monitoring() {
    log_info "[7/8] Setting up monitoring script..."
    
    cat > /usr/local/bin/apache-memory-monitor.sh << 'EOF'
#!/bin/bash
APACHE_PROC="apache2"
command -v httpd >/dev/null && APACHE_PROC="httpd"

echo "Apache Memory Usage Report - $(date)"
echo "=================================="
ps aux | grep $APACHE_PROC | grep -v grep | awk '{sum+=$6} END {print "Total Memory: " sum/1024 " MB"}'
echo "Active processes: $(pgrep $APACHE_PROC | wc -l)"
echo "Top 5 memory consuming Apache processes:"
ps aux | grep $APACHE_PROC | grep -v grep | sort -k6 -nr | head -5 | awk '{print $6/1024 " MB - PID " $2}'
EOF
    
    chmod 755 /usr/local/bin/apache-memory-monitor.sh
    chown root:root /usr/local/bin/apache-memory-monitor.sh
    
    log_info "Monitoring script installed at /usr/local/bin/apache-memory-monitor.sh"
}

# Restart and verify
restart_and_verify() {
    log_info "[8/8] Restarting Apache and verifying configuration..."
    
    # Test configuration
    if ! $APACHE_CTL configtest >/dev/null 2>&1; then
        log_error "Configuration test failed. Restoring backup..."
        cp -r "$BACKUP_DIR"/* "$APACHE_CONF_DIR"/
        exit 1
    fi
    
    # Restart Apache
    systemctl restart "$APACHE_SERVICE"
    systemctl enable "$APACHE_SERVICE" >/dev/null 2>&1
    
    # Verify Apache is running
    if systemctl is-active --quiet "$APACHE_SERVICE"; then
        log_info "Apache successfully optimized and running!"
        
        # Show current MPM
        echo "Current MPM: $($APACHE_CTL -V | grep -i mpm || echo 'Could not detect MPM')"
        echo "Active processes: $(pgrep apache2 httpd 2>/dev/null | wc -l)"
        echo "Run '/usr/local/bin/apache-memory-monitor.sh' to monitor memory usage"
    else
        log_error "Apache failed to start after optimization"
        exit 1
    fi
}

# Main function
main() {
    local MAX_WORKERS=""
    
    # Parse arguments
    while [[ $# -gt 0 ]]; do
        case $1 in
            -m|--max-workers)
                MAX_WORKERS="$2"
                shift 2
                ;;
            -h|--help)
                usage
                ;;
            *)
                log_error "Unknown option: $1"
                usage
                ;;
        esac
    done
    
    log_info "[1/8] Starting Apache memory optimization..."
    
    check_root
    detect_distro
    create_backup
    install_packages
    configure_event_mpm
    disable_modules
    optimize_apache_config
    setup_monitoring
    restart_and_verify
    
    log_info "Apache optimization completed successfully!"
}

main "$@"