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| 1 | +Rate Limiting Middleware |
| 2 | +######################## |
| 3 | + |
| 4 | +.. versionadded:: 5.3 |
| 5 | + |
| 6 | +The ``RateLimitMiddleware`` provides configurable rate limiting for your |
| 7 | +application to protect against abuse and ensure fair usage of resources. |
| 8 | + |
| 9 | +Basic Usage |
| 10 | +=========== |
| 11 | + |
| 12 | +To use rate limiting in your application, add the middleware to your |
| 13 | +middleware queue:: |
| 14 | + |
| 15 | + // In src/Application.php |
| 16 | + use Cake\Http\Middleware\RateLimitMiddleware; |
| 17 | + |
| 18 | + public function middleware(MiddlewareQueue $middlewareQueue): MiddlewareQueue |
| 19 | + { |
| 20 | + $middlewareQueue |
| 21 | + // ... other middleware |
| 22 | + ->add(new RateLimitMiddleware([ |
| 23 | + 'limit' => 60, // 60 requests |
| 24 | + 'window' => 60, // per 60 seconds |
| 25 | + 'identifier' => 'ip', // based on IP address |
| 26 | + ])); |
| 27 | + |
| 28 | + return $middlewareQueue; |
| 29 | + } |
| 30 | + |
| 31 | +When a client exceeds the rate limit, they will receive a |
| 32 | +``429 Too Many Requests`` response. |
| 33 | + |
| 34 | +Configuration Options |
| 35 | +===================== |
| 36 | + |
| 37 | +The middleware accepts the following configuration options: |
| 38 | + |
| 39 | +- **limit** - Maximum number of requests allowed (default: 60) |
| 40 | +- **window** - Time window in seconds (default: 60) |
| 41 | +- **identifier** - How to identify clients: 'ip', 'user', 'route', 'api_key' (default: 'ip') |
| 42 | +- **strategy** - Rate limiting algorithm: 'sliding_window', 'fixed_window', 'token_bucket' (default: 'sliding_window') |
| 43 | +- **cache** - Cache configuration to use (default: 'default') |
| 44 | +- **headers** - Whether to include rate limit headers in responses (default: true) |
| 45 | +- **message** - Custom error message for rate limit exceeded |
| 46 | +- **skipCheck** - Callback to determine if a request should skip rate limiting |
| 47 | +- **costCallback** - Callback to determine the cost of a request |
| 48 | +- **identifierCallback** - Callback to determine the identifier for a request |
| 49 | +- **limitCallback** - Callback to determine the limit for a specific identifier |
| 50 | + |
| 51 | +Identifier Types |
| 52 | +================ |
| 53 | + |
| 54 | +IP Address |
| 55 | +---------- |
| 56 | + |
| 57 | +The default identifier type tracks requests by IP address:: |
| 58 | + |
| 59 | + new RateLimitMiddleware([ |
| 60 | + 'identifier' => 'ip', |
| 61 | + 'limit' => 100, |
| 62 | + 'window' => 60, |
| 63 | + ]) |
| 64 | + |
| 65 | +The middleware automatically handles proxy headers like ``X-Forwarded-For`` |
| 66 | +and ``CF-Connecting-IP``. |
| 67 | + |
| 68 | +User-based |
| 69 | +---------- |
| 70 | + |
| 71 | +Track requests per authenticated user:: |
| 72 | + |
| 73 | + new RateLimitMiddleware([ |
| 74 | + 'identifier' => 'user', |
| 75 | + 'limit' => 1000, |
| 76 | + 'window' => 3600, // 1 hour |
| 77 | + ]) |
| 78 | + |
| 79 | +This requires authentication middleware to be loaded before rate limiting. |
| 80 | + |
| 81 | +Route-based |
| 82 | +----------- |
| 83 | + |
| 84 | +Apply different limits to different routes:: |
| 85 | + |
| 86 | + new RateLimitMiddleware([ |
| 87 | + 'identifier' => 'route', |
| 88 | + 'limit' => 10, |
| 89 | + 'window' => 60, |
| 90 | + ]) |
| 91 | + |
| 92 | +This creates separate limits for each controller/action combination. |
| 93 | + |
| 94 | +API Key |
| 95 | +------- |
| 96 | + |
| 97 | +Track requests by API key:: |
| 98 | + |
| 99 | + new RateLimitMiddleware([ |
| 100 | + 'identifier' => 'api_key', |
| 101 | + 'limit' => 5000, |
| 102 | + 'window' => 3600, |
| 103 | + ]) |
| 104 | + |
| 105 | +The middleware looks for API keys in the ``X-API-Key`` header or |
| 106 | +``api_key`` query parameter. |
| 107 | + |
| 108 | +Custom Identifiers |
| 109 | +================== |
| 110 | + |
| 111 | +You can create custom identifiers using a callback:: |
| 112 | + |
| 113 | + new RateLimitMiddleware([ |
| 114 | + 'identifierCallback' => function ($request) { |
| 115 | + // Custom logic to identify the client |
| 116 | + $tenant = $request->getHeader('X-Tenant-ID'); |
| 117 | + return 'tenant_' . $tenant[0]; |
| 118 | + }, |
| 119 | + ]) |
| 120 | + |
| 121 | +Rate Limiting Strategies |
| 122 | +======================== |
| 123 | + |
| 124 | +Sliding Window |
| 125 | +-------------- |
| 126 | + |
| 127 | +The default strategy that provides smooth rate limiting by continuously |
| 128 | +adjusting the window based on request timing:: |
| 129 | + |
| 130 | + new RateLimitMiddleware([ |
| 131 | + 'strategy' => 'sliding_window', |
| 132 | + ]) |
| 133 | + |
| 134 | +Fixed Window |
| 135 | +------------ |
| 136 | + |
| 137 | +Resets the counter at fixed intervals:: |
| 138 | + |
| 139 | + new RateLimitMiddleware([ |
| 140 | + 'strategy' => 'fixed_window', |
| 141 | + ]) |
| 142 | + |
| 143 | +Token Bucket |
| 144 | +------------ |
| 145 | + |
| 146 | +Allows for burst capacity while maintaining an average rate:: |
| 147 | + |
| 148 | + new RateLimitMiddleware([ |
| 149 | + 'strategy' => 'token_bucket', |
| 150 | + 'limit' => 100, // bucket capacity |
| 151 | + 'window' => 60, // refill rate |
| 152 | + ]) |
| 153 | + |
| 154 | +Advanced Usage |
| 155 | +============== |
| 156 | + |
| 157 | +Skip Rate Limiting |
| 158 | +------------------ |
| 159 | + |
| 160 | +Skip rate limiting for certain requests:: |
| 161 | + |
| 162 | + new RateLimitMiddleware([ |
| 163 | + 'skipCheck' => function ($request) { |
| 164 | + // Skip rate limiting for health checks |
| 165 | + return $request->getParam('action') === 'health'; |
| 166 | + }, |
| 167 | + ]) |
| 168 | + |
| 169 | +Request Cost |
| 170 | +------------ |
| 171 | + |
| 172 | +Assign different costs to different types of requests:: |
| 173 | + |
| 174 | + new RateLimitMiddleware([ |
| 175 | + 'costCallback' => function ($request) { |
| 176 | + // POST requests cost 5x more |
| 177 | + return $request->getMethod() === 'POST' ? 5 : 1; |
| 178 | + }, |
| 179 | + ]) |
| 180 | + |
| 181 | +Dynamic Limits |
| 182 | +-------------- |
| 183 | + |
| 184 | +Set different limits for different users or plans:: |
| 185 | + |
| 186 | + new RateLimitMiddleware([ |
| 187 | + 'limitCallback' => function ($request, $identifier) { |
| 188 | + $user = $request->getAttribute('identity'); |
| 189 | + if ($user && $user->plan === 'premium') { |
| 190 | + return 10000; // Premium users get higher limit |
| 191 | + } |
| 192 | + return 100; // Free tier limit |
| 193 | + }, |
| 194 | + ]) |
| 195 | + |
| 196 | +Rate Limit Headers |
| 197 | +================== |
| 198 | + |
| 199 | +When enabled, the middleware adds the following headers to responses: |
| 200 | + |
| 201 | +- ``X-RateLimit-Limit`` - The maximum number of requests allowed |
| 202 | +- ``X-RateLimit-Remaining`` - The number of requests remaining |
| 203 | +- ``X-RateLimit-Reset`` - Unix timestamp when the rate limit resets |
| 204 | +- ``X-RateLimit-Reset-Date`` - ISO 8601 date when the rate limit resets |
| 205 | + |
| 206 | +Multiple Rate Limiters |
| 207 | +====================== |
| 208 | + |
| 209 | +You can apply multiple rate limiters with different configurations:: |
| 210 | + |
| 211 | + // Strict limit for login attempts |
| 212 | + $middlewareQueue->add(new RateLimitMiddleware([ |
| 213 | + 'identifier' => 'ip', |
| 214 | + 'limit' => 5, |
| 215 | + 'window' => 900, // 15 minutes |
| 216 | + 'skipCheck' => function ($request) { |
| 217 | + return $request->getParam('action') !== 'login'; |
| 218 | + }, |
| 219 | + ])); |
| 220 | + |
| 221 | + // General API rate limit |
| 222 | + $middlewareQueue->add(new RateLimitMiddleware([ |
| 223 | + 'identifier' => 'api_key', |
| 224 | + 'limit' => 1000, |
| 225 | + 'window' => 3600, |
| 226 | + ])); |
| 227 | + |
| 228 | +Cache Configuration |
| 229 | +=================== |
| 230 | + |
| 231 | +The rate limiter stores its data in cache. Make sure you have a persistent |
| 232 | +cache configured:: |
| 233 | + |
| 234 | + // In config/app.php |
| 235 | + 'Cache' => [ |
| 236 | + 'rate_limit' => [ |
| 237 | + 'className' => 'Redis', |
| 238 | + 'prefix' => 'rate_limit_', |
| 239 | + 'duration' => '+1 hour', |
| 240 | + ], |
| 241 | + ], |
| 242 | + |
| 243 | +Then use it in the middleware:: |
| 244 | + |
| 245 | + new RateLimitMiddleware([ |
| 246 | + 'cache' => 'rate_limit', |
| 247 | + ]) |
| 248 | + |
| 249 | +.. warning:: |
| 250 | + The ``File`` cache engine is not recommended for production use with |
| 251 | + rate limiting as it may not handle concurrent requests properly. |
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