Configure Apache reverse proxy with caching for microservices

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

# Apache Reverse Proxy with Caching Setup Script
# Configures Apache with mod_proxy and mod_cache for microservices

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m'

# Cleanup function for error handling
cleanup() {
    echo -e "${RED}[ERROR] Installation failed. Check logs above for details.${NC}"
    exit 1
}

trap cleanup ERR

# Usage message
usage() {
    echo "Usage: $0 <domain_name> [backend_service_1:port] [backend_service_2:port] ..."
    echo "Example: $0 api.example.com localhost:3000 localhost:3001"
    exit 1
}

# Check arguments
if [ $# -lt 2 ]; then
    usage
fi

DOMAIN_NAME="$1"
shift
BACKEND_SERVICES=("$@")

# Check if running as root or with sudo
if [ "$EUID" -ne 0 ]; then
    echo -e "${RED}[ERROR] This script must be run as root or with sudo${NC}"
    exit 1
fi

# Auto-detect distribution
if [ -f /etc/os-release ]; then
    . /etc/os-release
    case "$ID" in
        ubuntu|debian)
            PKG_MGR="apt"
            PKG_UPDATE="apt update && apt upgrade -y"
            PKG_INSTALL="apt install -y"
            APACHE_SERVICE="apache2"
            APACHE_CONFIG_DIR="/etc/apache2"
            SITES_DIR="/etc/apache2/sites-available"
            SITES_ENABLED="/etc/apache2/sites-enabled"
            APACHE_USER="www-data"
            USE_A2ENMOD=true
            ;;
        almalinux|rocky|centos|rhel|ol|fedora)
            PKG_MGR="dnf"
            PKG_UPDATE="dnf update -y"
            PKG_INSTALL="dnf install -y"
            APACHE_SERVICE="httpd"
            APACHE_CONFIG_DIR="/etc/httpd"
            SITES_DIR="/etc/httpd/conf.d"
            APACHE_USER="apache"
            USE_A2ENMOD=false
            ;;
        amzn)
            PKG_MGR="yum"
            PKG_UPDATE="yum update -y"
            PKG_INSTALL="yum install -y"
            APACHE_SERVICE="httpd"
            APACHE_CONFIG_DIR="/etc/httpd"
            SITES_DIR="/etc/httpd/conf.d"
            APACHE_USER="apache"
            USE_A2ENMOD=false
            ;;
        *)
            echo -e "${RED}[ERROR] Unsupported distribution: $ID${NC}"
            exit 1
            ;;
    esac
else
    echo -e "${RED}[ERROR] Cannot detect distribution${NC}"
    exit 1
fi

echo -e "${GREEN}[1/8] Updating system packages...${NC}"
$PKG_UPDATE

echo -e "${GREEN}[2/8] Installing Apache HTTP Server...${NC}"
if [ "$PKG_MGR" = "apt" ]; then
    $PKG_INSTALL apache2 apache2-utils
else
    $PKG_INSTALL httpd httpd-tools
fi

echo -e "${GREEN}[3/8] Enabling required Apache modules...${NC}"
if [ "$USE_A2ENMOD" = true ]; then
    # Debian/Ubuntu systems
    a2enmod proxy
    a2enmod proxy_http
    a2enmod proxy_balancer
    a2enmod lbmethod_byrequests
    a2enmod cache
    a2enmod cache_disk
    a2enmod headers
    a2enmod rewrite
else
    # RHEL-based systems - modules are loaded via configuration
    MAIN_CONFIG="${APACHE_CONFIG_DIR}/conf/httpd.conf"
    
    # Check if modules are already loaded to avoid duplicates
    if ! grep -q "LoadModule proxy_module" "$MAIN_CONFIG"; then
        cat >> "$MAIN_CONFIG" << 'EOF'

# Proxy and Cache modules
LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so
LoadModule proxy_balancer_module modules/mod_proxy_balancer.so
LoadModule lbmethod_byrequests_module modules/mod_lbmethod_byrequests.so
LoadModule cache_module modules/mod_cache.so
LoadModule cache_disk_module modules/mod_cache_disk.so
LoadModule headers_module modules/mod_headers.so
LoadModule rewrite_module modules/mod_rewrite.so
EOF
    fi
fi

echo -e "${GREEN}[4/8] Creating cache directory...${NC}"
CACHE_DIR="/var/cache/${APACHE_SERVICE}/mod_cache_disk"
mkdir -p "$CACHE_DIR"
chown "$APACHE_USER:$APACHE_USER" "$CACHE_DIR"
chmod 755 "$CACHE_DIR"

echo -e "${GREEN}[5/8] Configuring Apache performance settings...${NC}"
MAIN_CONFIG_FILE="${APACHE_CONFIG_DIR}/apache2.conf"
if [ "$PKG_MGR" != "apt" ]; then
    MAIN_CONFIG_FILE="${APACHE_CONFIG_DIR}/conf/httpd.conf"
fi

if ! grep -q "MaxRequestWorkers 400" "$MAIN_CONFIG_FILE"; then
    cat >> "$MAIN_CONFIG_FILE" << 'EOF'

# Performance tuning for proxy workloads
MaxRequestWorkers 400
ThreadsPerChild 25
StartServers 3
MinSpareThreads 75
MaxSpareThreads 250

# Proxy timeout settings
ProxyTimeout 300
ProxyPreserveHost On

# Security headers
Header always set X-Frame-Options DENY
Header always set X-Content-Type-Options nosniff
Header always set Referrer-Policy strict-origin-when-cross-origin
EOF
fi

echo -e "${GREEN}[6/8] Creating virtual host configuration...${NC}"

# Build proxy balancer configuration
BALANCER_CONFIG=""
BALANCER_MEMBERS=""
for i in "${!BACKEND_SERVICES[@]}"; do
    service="${BACKEND_SERVICES[$i]}"
    BALANCER_MEMBERS+="    BalancerMember http://${service}\\n"
done

# Create virtual host configuration
VHOST_CONFIG="${SITES_DIR}/${DOMAIN_NAME}.conf"

cat > "$VHOST_CONFIG" << EOF
<VirtualHost *:80>
    ServerName ${DOMAIN_NAME}
    DocumentRoot /var/www/html

    # Enable caching
    CacheEnable disk /
    CacheRoot ${CACHE_DIR}
    CacheDirLevels 2
    CacheDirLength 1
    CacheDefaultExpire 3600
    CacheMaxExpire 86400
    CacheMinExpire 60
    CacheDetailHeader on
    CacheHeader on

    # Cache policies for different content types
    <LocationMatch "\.(css|js|png|jpg|jpeg|gif|ico|svg)$">
        CacheDefaultExpire 604800
        ExpiresActive On
        ExpiresDefault "access plus 1 week"
        Header set Cache-Control "public, max-age=604800"
    </LocationMatch>

    <LocationMatch "\.(json|xml)$">
        CacheDefaultExpire 300
        ExpiresActive On
        ExpiresDefault "access plus 5 minutes"
        Header set Cache-Control "public, max-age=300"
    </LocationMatch>

    # Proxy balancer configuration
    ProxyPreserveHost On
    ProxyRequests Off

    <Proxy balancer://microservices>
$(echo -e "$BALANCER_MEMBERS")
        ProxySet lbmethod=byrequests
    </Proxy>

    # Route all requests to the balancer
    ProxyPassMatch ^/(.*)$ balancer://microservices/\$1
    ProxyPassReverse / balancer://microservices/

    # Balancer manager (restrict access in production)
    <Location "/balancer-manager">
        SetHandler balancer-manager
        Require local
    </Location>
    ProxyPass /balancer-manager !

    # Logging
    ErrorLog \${APACHE_LOG_DIR}/${DOMAIN_NAME}_error.log
    CustomLog \${APACHE_LOG_DIR}/${DOMAIN_NAME}_access.log combined
</VirtualHost>
EOF

chmod 644 "$VHOST_CONFIG"

echo -e "${GREEN}[7/8] Enabling virtual host and starting Apache...${NC}"

if [ "$USE_A2ENMOD" = true ]; then
    # Enable site on Debian/Ubuntu
    a2ensite "${DOMAIN_NAME}.conf"
    # Disable default site if it exists
    if [ -f "/etc/apache2/sites-enabled/000-default.conf" ]; then
        a2dissite 000-default
    fi
fi

# Test Apache configuration
if "${APACHE_SERVICE}" -t; then
    echo -e "${YELLOW}Apache configuration test passed${NC}"
else
    echo -e "${RED}[ERROR] Apache configuration test failed${NC}"
    exit 1
fi

# Start and enable Apache service
systemctl enable "$APACHE_SERVICE"
systemctl restart "$APACHE_SERVICE"

# Configure firewall if present
if command -v firewall-cmd &> /dev/null && systemctl is-active --quiet firewalld; then
    echo -e "${YELLOW}Configuring firewalld...${NC}"
    firewall-cmd --permanent --add-service=http
    firewall-cmd --reload
elif command -v ufw &> /dev/null; then
    echo -e "${YELLOW}Configuring ufw...${NC}"
    ufw --force enable
    ufw allow 80/tcp
fi

echo -e "${GREEN}[8/8] Verifying installation...${NC}"

# Check if Apache is running
if systemctl is-active --quiet "$APACHE_SERVICE"; then
    echo -e "${GREEN}✓ Apache is running${NC}"
else
    echo -e "${RED}✗ Apache is not running${NC}"
    exit 1
fi

# Check if cache directory exists and has correct permissions
if [ -d "$CACHE_DIR" ] && [ "$(stat -c %U:%G "$CACHE_DIR")" = "${APACHE_USER}:${APACHE_USER}" ]; then
    echo -e "${GREEN}✓ Cache directory configured correctly${NC}"
else
    echo -e "${RED}✗ Cache directory configuration failed${NC}"
    exit 1
fi

# Check if virtual host file exists
if [ -f "$VHOST_CONFIG" ]; then
    echo -e "${GREEN}✓ Virtual host configuration created${NC}"
else
    echo -e "${RED}✗ Virtual host configuration missing${NC}"
    exit 1
fi

echo -e "${GREEN}[SUCCESS] Apache reverse proxy with caching has been configured successfully!${NC}"
echo -e "${YELLOW}Configuration details:${NC}"
echo "  - Domain: ${DOMAIN_NAME}"
echo "  - Backend services: ${BACKEND_SERVICES[*]}"
echo "  - Cache directory: ${CACHE_DIR}"
echo "  - Virtual host config: ${VHOST_CONFIG}"
echo "  - Balancer manager: http://${DOMAIN_NAME}/balancer-manager"
echo ""
echo -e "${YELLOW}Next steps:${NC}"
echo "1. Update your DNS to point ${DOMAIN_NAME} to this server"
echo "2. Test the setup: curl -H 'Host: ${DOMAIN_NAME}' http://localhost/"
echo "3. Monitor logs: tail -f ${APACHE_LOG_DIR}/${DOMAIN_NAME}_access.log"
echo "4. Consider setting up SSL/TLS certificates for production use"