When setting up an Apache reverse proxy, there are cases where you need certain directories to bypass the proxy and be served directly from the local filesystem. A common scenario is when you want to:

• Proxy most requests to a backend application (e.g., Tomcat on port 8080)
• Serve static assets (images, CSS, JS) directly from the filesystem for better performance
• Maintain some legacy content outside the proxied application

The most effective approach is to use Location or LocationMatch directives to define exceptions:

<VirtualHost *:80>
    ServerName localhost
    
    # General proxy settings
    ProxyRequests Off
    ProxyPreserveHost On
    ProxyTimeout 600
    
    # Exception for /images
    <Location /images>
        ProxyPass !
    </Location>
    
    # Exception for specific file types
    <LocationMatch "\.(jpg|png|gif|css|js)$">
        ProxyPass !
    </LocationMatch>
    
    # Default proxy rule
    ProxyPass / http://localhost:8080/myapp/
    ProxyPassReverse / http://localhost:8080/myapp/
</VirtualHost>

For more complex routing logic, you can combine mod_rewrite with proxy rules:

RewriteEngine On

# Skip proxy for /images
RewriteRule ^/images - [L]

# Skip proxy for specific file patterns
RewriteCond %{REQUEST_URI} \.(css|js|jpg|png|gif)$ [NC]
RewriteRule ^ - [L]

# Proxy everything else
RewriteRule ^/(.*) http://localhost:8080/myapp/$1 [P,L]

When implementing proxy exceptions:

• Place more specific exceptions before general rules
• Use LocationMatch for pattern-based exclusions
• Consider filesystem permissions for directly served content
• Benchmark with and without exceptions to verify performance gains

If exceptions aren't working as expected:

1. Enable verbose logging with LogLevel debug
2. Check the order of directives in your config
3. Verify filesystem permissions for excluded paths
4. Test with curl -v to inspect headers and responses

When implementing reverse proxy configurations in Apache, a common requirement emerges: proxying most requests to a backend application while excluding specific directories that should be served directly from the local filesystem. This scenario frequently occurs when:

• Static assets (images, CSS, JS) should be served directly for performance
• Certain API endpoints need to bypass the proxy
• Admin interfaces require direct access

The existing setup shows a basic reverse proxy configuration:

ProxyRequests Off
ProxyTimeout 600
ProxyPreserveHost On
ProxyPass / http://localhost:8080/
ProxyPassReverse / http://localhost:8080/
RewriteEngine On
RewriteRule ^/(.*) http://localhost:8080/VirtualHostBase/http/%{SERVER_NAME}:80/myapp/VirtualHostRoot/$1 [L,P]

To exclude the /images directory from being proxied, we need to modify the configuration. Here are three approaches:

Option 1: Using ProxyPass Exceptions

ProxyRequests Off
ProxyPreserveHost On

# Exclude /images from proxying
ProxyPass /images !

# Proxy all other requests
ProxyPass / http://localhost:8080/myapp/
ProxyPassReverse / http://localhost:8080/myapp/

Option 2: Combining ProxyPass with Location

<Location />
    ProxyPass http://localhost:8080/myapp/
    ProxyPassReverse http://localhost:8080/myapp/
</Location>

<Location /images>
    ProxyPass !
    DocumentRoot /var/www/html
</Location>

Option 3: Using mod_rewrite with Conditions

RewriteEngine On

# Skip proxy for /images
RewriteCond %{REQUEST_URI} ^/images [NC]
RewriteRule ^ - [L]

# Proxy all other requests
RewriteRule ^/(.*) http://localhost:8080/VirtualHostBase/http/%{SERVER_NAME}:80/myapp/VirtualHostRoot/$1 [P]

For multiple directory exceptions, regular expressions can be powerful:

ProxyPassMatch ^/(images|css|js) !
ProxyPass / http://localhost:8080/myapp/
ProxyPassReverse / http://localhost:8080/myapp/

When implementing proxy exceptions:

• Place frequent exceptions first in configuration
• Use simple pattern matching when possible
• Consider filesystem permissions for excluded directories
• Test with curl -v to verify request routing

Common issues and solutions: