Request ID

middleware.RequestID reads or creates a request identifier, stores it on the request context, and writes it to the response header.

app.Use(middleware.RequestID())

The default header is X-Request-ID. A client-provided value is reused. If it is missing, the middleware generates one.

Options

app.Use(middleware.RequestID(middleware.RequestIDConfig{
	Header: "X-Trace-ID",
	Length: 24,
	Generator: func() string {
		return "req-" + time.Now().Format("20060102150405")
	},
}))

The default generator produces Length random bytes and hex encodes them, so the visible ID is twice the configured length. If the system random source fails, it falls back to a process ID and counter value.

Reading the ID

The ID is available in the request session:

app.Get("/", func(c *core.Context) {
	id := c.GetSession("request_id")
	c.JSON(200, map[string]any{"request_id": id})
})

It is also present on the response:

X-Request-ID: 8f14e45fceea167a5a36dedd4bea2543

Use with logging

Place RequestID before Logger so every log line can include the same ID. The current logger prints method, path, and status. If you need the ID in the line, use a custom middleware around Logger or configure a structured logger in the application.

Notes

• The middleware does not validate client-provided IDs. Treat them as opaque strings and do not use them for authorization.
• When a trusted edge proxy already sets an ID, keep the default behavior so the proxy value is preserved.
• Use a bounded length for generated IDs. Very large values add unnecessary header and log volume.