Body Limit Middleware¶

Limits the maximum size of request bodies.

Usage¶

app.Use(middleware.BodyLimit(10 * middleware.MB))

Size Constants¶

Examples¶

Global Limit¶

// 10 MB limit for all requests
app.Use(middleware.BodyLimit(10 * middleware.MB))

Per-Group Limits¶

// Strict limit for JSON API
api := app.Group("/api")
api.Use(middleware.BodyLimit(1 * middleware.MB))

// Relaxed limit for file uploads
uploads := app.Group("/uploads")
uploads.Use(middleware.BodyLimit(100 * middleware.MB))

Specific Sizes¶

middleware.BodyLimit(100 * middleware.KB) // 100 KB
middleware.BodyLimit(5 * middleware.MB)   // 5 MB
middleware.BodyLimit(1 * middleware.GB)   // 1 GB
middleware.BodyLimit(500 * 1024)          // 500 KB (custom)

Response¶

When the body exceeds the limit:

HTTP/1.1 413 Request Entity Too Large
Content-Type: application/json; charset=utf-8

{"error": "request body too large"}

How It Works¶

1. Fast path — if Content-Length is present and already exceeds the limit, the request is rejected immediately before reading any bytes
2. Streaming path — wraps the request body with a counting reader; if bytes read exceed the limit during the handler's read, the middleware intercepts the error on the way back and responds 413

This covers both normal requests (with Content-Length) and chunked-encoded requests (without Content-Length).

Best Practices¶

1. Set appropriate limits — balance security and usability
2. Use per-group limits — different endpoints often have very different needs
3. Document your limits — include them in API docs so clients can handle 413 gracefully
4. Pair with BodyLimit for uploads — combine with multipart/form-data parsing for file upload endpoints

Common Limits by Use Case¶