Apache2

1. INSTALLATION COMMANDS

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

# CentOS/RHEL/Fedora
sudo yum install httpd httpd-tools  # or dnf

# Enable at boot & start
sudo systemctl enable apache2  # or httpd
sudo systemctl start apache2

2. BASIC SITE CONFIG

# /etc/apache2/sites-available/mysite.conf
<VirtualHost *:80>
    ServerName mysite.com
    ServerAlias www.mysite.com
    
    DocumentRoot /var/www/mysite
    
    <Directory /var/www/mysite>
        Options -Indexes +FollowSymLinks
        AllowOverride All
        Require all granted
    </Directory>
    
    ErrorLog ${APACHE_LOG_DIR}/mysite-error.log
    CustomLog ${APACHE_LOG_DIR}/mysite-access.log combined
</VirtualHost>

3. ENABLE SITE COMMANDS

# Ubuntu/Debian
sudo a2ensite mysite.conf
sudo systemctl reload apache2

# CentOS/RHEL (just copy to conf.d)
sudo cp mysite.conf /etc/httpd/conf.d/
sudo systemctl reload httpd

4. CUSTOM ERROR PAGES — MINIMAL CONFIG

Option A: Global (in virtual host)

<VirtualHost *:80>
    # ... other config ...
    
    # Point to your custom error pages directory
    ErrorDocument 400 /errors/400.html
    ErrorDocument 401 /errors/401.html
    ErrorDocument 403 /errors/403.html
    ErrorDocument 404 /errors/404.html
    ErrorDocument 500 /errors/500.html
    ErrorDocument 502 /errors/502.html
    ErrorDocument 503 /errors/503.html
    ErrorDocument 504 /errors/504.html
</VirtualHost>

Option B: Directory-based (in .htaccess)

# .htaccess in your site root
ErrorDocument 404 /404.html
ErrorDocument 500 /500.html

Option C: Complete error handling config

<VirtualHost *:80>
    # ... other config ...
    
    # Custom error docs
    Alias /errors "/var/www/mysite/errors"
    ErrorDocument 404 /errors/404.html
    ErrorDocument 500 /errors/500.html
    
    # Make error pages accessible
    <Directory "/var/www/mysite/errors">
        Require all granted
        Options -Indexes
    </Directory>
</VirtualHost>

5. MAINTENANCE MODE CONFIG

# /etc/apache2/sites-available/maintenance.conf
<VirtualHost *:80>
    ServerName mysite.com
    
    DocumentRoot /var/www/maintenance
    
    # Allow only specific IPs
    <Directory /var/www/maintenance>
        Order deny,allow
        Deny from all
        Allow from 192.168.1.0/24  # Your office IP
        Allow from 10.0.0.0/8      # Your VPN
        ErrorDocument 403 /maintenance.html
    </Directory>
    
    ErrorDocument 503 /maintenance.html
</VirtualHost>

6. TESTING ERROR PAGES

# Quick curl tests
curl -I http://mysite.com/nonexistent-page  # Should show 404
curl -I http://mysite.com/server-error      # If you have error generator

# Check Apache config
sudo apache2ctl configtest

# Test specific error
sudo tail -f /var/log/apache2/error.log

7. ONE-LINER ERROR PAGE SETUP

# Create basic error pages directory
mkdir -p /var/www/mysite/errors
echo "404 - Not Found" > /var/www/mysite/errors/404.html
echo "500 - Server Error" > /var/www/mysite/errors/500.html

# Add to Apache config
echo 'ErrorDocument 404 /errors/404.html' >> /etc/apache2/sites-available/mysite.conf
echo 'ErrorDocument 500 /errors/500.html' >> /etc/apache2/sites-available/mysite.conf

# Reload
sudo systemctl reload apache2

8. BONUS: REVERSE PROXY ERROR PAGES

<VirtualHost *:80>
    ProxyPass / http://backend:3000/
    ProxyPassReverse / http://backend:3000/
    
    # Handle backend errors
    ProxyErrorOverride On
    ErrorDocument 502 /errors/502.html
    ErrorDocument 503 /errors/503.html
    ErrorDocument 504 /errors/504.html
</VirtualHost>

That’s it — just the configs, no fluff. Enable, reload, test.