Idempotency

Idempotency middleware for Fiber allows for fault-tolerant APIs where duplicate requests — for example due to networking issues on the client-side — do not erroneously cause the same action performed multiple times on the server-side.

Refer to https://datatracker.ietf.org/doc/html/draft-ietf-httpapi-idempotency-key-header-02 for a better understanding.

Signatures

func New(config ...Config) fiber.Handler

Examples

Import the middleware package that is part of the Fiber web framework

import (
	"github.com/gofiber/fiber/v2"
	"github.com/gofiber/fiber/v2/middleware/idempotency"
)

After you initiate your Fiber app, you can use the following possibilities:

Default Config

app.Use(idempotency.New())

Custom Config

app.Use(idempotency.New(idempotency.Config{
	Lifetime: 42 * time.Minute,
	// ...
}))

Config

Property	Type	Description	Default
Next	func(*fiber.Ctx) bool	Next defines a function to skip this middleware when returned true.	A function for safe methods
Lifetime	time.Duration	Lifetime is the maximum lifetime of an idempotency key.	30 * time.Minute
KeyHeader	string	KeyHeader is the name of the header that contains the idempotency key.	"X-Idempotency-Key"
KeyHeaderValidate	func(string) error	KeyHeaderValidate defines a function to validate the syntax of the idempotency header.	A function for UUID validation
KeepResponseHeaders	[]string	KeepResponseHeaders is a list of headers that should be kept from the original response.	nil (keep all headers)
Lock	Locker	Lock locks an idempotency key.	An in-memory locker
Storage	fiber.Storage	Storage stores response data by idempotency key.	An in-memory storage

Default Config

var ConfigDefault = Config{
	Next: func(c *fiber.Ctx) bool {
		// Skip middleware if the request was done using a safe HTTP method
		return fiber.IsMethodSafe(c.Method())
	},

	Lifetime: 30 * time.Minute,

	KeyHeader: "X-Idempotency-Key",
	KeyHeaderValidate: func(k string) error {
		if l, wl := len(k), 36; l != wl { // UUID length is 36 chars
			return fmt.Errorf("%w: invalid length: %d != %d", ErrInvalidIdempotencyKey, l, wl)
		}

		return nil
	},

	KeepResponseHeaders: nil,

	Lock: nil, // Set in configDefault so we don't allocate data here.

	Storage: nil, // Set in configDefault so we don't allocate data here.
}