Rate Limiter

RateLimiter provides a rate limiter middleware that limits the number of requests sent to the server from a particular IP or identifier within a time period.

By default, an in-memory store keeps track of requests. The default in-memory implementation is focused on correctness and may not be the best option for a high number of concurrent requests or a large number of distinct identifiers (>16k).

All core middleware lives in the middleware package:

import "github.com/labstack/echo/v5/middleware"

Usage

To add a rate limit to your application, add the RateLimiter middleware. The example below limits the application to 20 requests/sec using the default in-memory store:

e.Use(middleware.RateLimiter(middleware.NewRateLimiterMemoryStore(20.0)))

Note

If the provided rate is a float number, Burst is treated as the rounded-down value of the rate.

Custom configuration

config := middleware.RateLimiterConfig{
  Skipper: middleware.DefaultSkipper,
  Store: middleware.NewRateLimiterMemoryStoreWithConfig(
    middleware.RateLimiterMemoryStoreConfig{Rate: 10, Burst: 30, ExpiresIn: 3 * time.Minute},
  ),
  IdentifierExtractor: func(c *echo.Context) (string, error) {
    id := c.RealIP()
    return id, nil
  },
  ErrorHandler: func(c *echo.Context, err error) error {
    return c.JSON(http.StatusForbidden, nil)
  },
  DenyHandler: func(c *echo.Context, identifier string, err error) error {
    return c.JSON(http.StatusTooManyRequests, nil)
  },
}

e.Use(middleware.RateLimiterWithConfig(config))

Errors

var (
  // ErrRateLimitExceeded denotes an error raised when the rate limit is exceeded.
  ErrRateLimitExceeded = echo.NewHTTPError(http.StatusTooManyRequests, "rate limit exceeded")
  // ErrExtractorError denotes an error raised when the extractor function is unsuccessful.
  ErrExtractorError = echo.NewHTTPError(http.StatusForbidden, "error while extracting identifier")
)

Tip

To implement your own store, satisfy the RateLimiterStore interface and pass it to RateLimiterConfig.

Configuration

type RateLimiterConfig struct {
  Skipper    Skipper
  BeforeFunc BeforeFunc
  // IdentifierExtractor uses echo.Context to extract the identifier for a visitor.
  IdentifierExtractor Extractor
  // Store defines a store for the rate limiter.
  Store RateLimiterStore
  // ErrorHandler provides a handler to be called when IdentifierExtractor returns a non-nil error.
  ErrorHandler func(c *echo.Context, err error) error
  // DenyHandler provides a handler to be called when RateLimiter denies access.
  DenyHandler func(c *echo.Context, identifier string, err error) error
}

Default configuration

// DefaultRateLimiterConfig defines default values for RateLimiterConfig.
var DefaultRateLimiterConfig = RateLimiterConfig{
  Skipper: DefaultSkipper,
  IdentifierExtractor: func(c *echo.Context) (string, error) {
    id := c.RealIP()
    return id, nil
  },
  ErrorHandler: func(c *echo.Context, err error) error {
    return &echo.HTTPError{
      Code:     ErrExtractorError.Code,
      Message:  ErrExtractorError.Message,
      Internal: err,
    }
  },
  DenyHandler: func(c *echo.Context, identifier string, err error) error {
    return &echo.HTTPError{
      Code:     ErrRateLimitExceeded.Code,
      Message:  ErrRateLimitExceeded.Message,
      Internal: err,
    }
  },
}