Apache Virtual Host Configuration — Virtual Host and Module Management

# Ubuntu / Debian
sudo apt update && sudo apt install -y apache2

# CentOS / RHEL
sudo yum install -y httpd

# Start the service
sudo systemctl enable --now apache2   # Ubuntu
sudo systemctl enable --now httpd     # CentOS

/etc/apache2/
├── apache2.conf        # Main configuration
├── sites-available/    # Virtual host configuration files
├── sites-enabled/      # Enabled sites (symbolic links)
├── mods-available/     # Available modules
└── mods-enabled/       # Enabled modules

# /etc/apache2/sites-available/example.com.conf
<VirtualHost *:80>
    ServerName  example.com
    ServerAlias www.example.com
    DocumentRoot /var/www/example.com

    <Directory /var/www/example.com>
        Options -Indexes +FollowSymLinks
        AllowOverride All
        Require all granted
    </Directory>

    ErrorLog  ${APACHE_LOG_DIR}/example.com-error.log
    CustomLog ${APACHE_LOG_DIR}/example.com-access.log combined
</VirtualHost>

# Enable the site
sudo a2ensite example.com.conf
sudo systemctl reload apache2

# Disable the site
sudo a2dissite 000-default.conf

<VirtualHost *:80>
    ServerName example.com
    Redirect permanent / https://example.com/
</VirtualHost>

<VirtualHost *:443>
    ServerName example.com
    DocumentRoot /var/www/example.com

    SSLEngine on
    SSLCertificateFile    /etc/letsencrypt/live/example.com/fullchain.pem
    SSLCertificateKeyFile /etc/letsencrypt/live/example.com/privkey.pem

    Header always set Strict-Transport-Security "max-age=31536000"
</VirtualHost>

# Enable modules
sudo a2enmod rewrite    # URL rewriting
sudo a2enmod ssl        # HTTPS
sudo a2enmod headers    # Header manipulation
sudo a2enmod proxy proxy_http  # Reverse proxy

# Disable a module
sudo a2dismod autoindex

# List enabled modules
apache2ctl -M

# /var/www/example.com/.htaccess
Options -Indexes
RewriteEngine On

# www → non-www
RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^ https://%1%{REQUEST_URI} [R=301,L]

# SPA routing (React, Vue, etc.)
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^ /index.html [L]

<VirtualHost *:443>
    ServerName api.example.com

    ProxyPreserveHost On
    ProxyPass        / http://127.0.0.1:3000/
    ProxyPassReverse / http://127.0.0.1:3000/

    RequestHeader set X-Forwarded-Proto "https"
</VirtualHost>

# Syntax check
sudo apache2ctl configtest
# or
sudo apachectl configtest

# Graceful reload (zero downtime)
sudo systemctl reload apache2