README

PSR-15 middleware that redirects apex (bare) domains to www-prefixed domains using HTTP 301 permanent redirects.

Introduction

Why This Library Exists

Many web applications need to canonicalize their URLs by redirecting apex domains (e.g., example.com) to their www-prefixed equivalents (e.g., www.example.com). This is important for:

• SEO consistency: Search engines treat example.com and www.example.com as different sites, potentially diluting page rank
• Cookie scope: Cookies set on www.example.com are more restrictive than those on the apex domain
• CDN and DNS flexibility: The www subdomain allows CNAME records, while apex domains typically require A records
• Load balancing: Subdomains provide more flexibility for DNS-based traffic distribution

This middleware handles the redirect automatically at the application layer, ensuring all requests arrive at the canonical www-prefixed domain.

Problems This Library Solves

1. Duplicate content issues: Without canonicalization, search engines index the same content under multiple URLs
2. Session inconsistencies: Cookies may not be shared between apex and www domains
3. Certificate complexity: Some CDNs and hosting providers handle www subdomains more gracefully
4. Manual redirect configuration: Eliminates the need to configure redirects at the web server level
5. Environment-aware prefixes: Supports developer-specific prefixes (e.g., www-pl.example.com) via APP_ENV

Where to Use This Library

• Mezzio applications: Add to your middleware pipeline early in the request lifecycle
• PSR-15 compatible frameworks: Any framework supporting PSR-15 middleware
• Multi-environment deployments: Use APP_ENV for developer-specific prefixes (e.g., development-pl creates www-pl.)
• Production web applications: Ensure consistent canonical URLs across all requests

Design Goals

1. Permanent redirects: Uses HTTP 301 status code for proper SEO handling
2. Query string preservation: Maintains all query parameters during redirect
3. Environment awareness: Supports custom prefixes via APP_ENV environment variable
4. Transparent operation: Only redirects when necessary, passes through already-prefixed requests
5. Zero configuration: Works out of the box with sensible defaults

Requirements

• PHP 8.3 or higher
• ctw/ctw-middleware ^4.0
• ctw/ctw-http ^4.0

Installation

Install by adding the package as a Composer requirement:

composer require ctw/ctw-middleware-apex

Usage Examples

Basic Pipeline Registration (Mezzio)

use Ctw\Middleware\ApexMiddleware\ApexMiddleware;

// In config/pipeline.php or similar
$app->pipe(ApexMiddleware::class);

Redirect Behavior

Environment-Aware Prefixes

When APP_ENV contains a two-letter suffix separated by a hyphen (e.g., development-pl), the middleware uses that as a developer-specific prefix:

# Environment variable
APP_ENV=development-pl

This enables multiple developers to work on the same domain with isolated environments.

ConfigProvider Registration

The package includes a ConfigProvider for automatic factory registration:

// config/config.php
return [
    // ...
    \Ctw\Middleware\ApexMiddleware\ConfigProvider::class,
];