Otelfiber

OpenTelemetry support for Fiber.

Can be found on OpenTelemetry Registry.

Note: Requires Go 1.19 and above

Install

This middleware supports Fiber v2.

go get -u github.com/gofiber/contrib/otelfiber/v2

Signature

otelfiber.Middleware(opts ...otelfiber.Option) fiber.Handler

Config

You can configure the middleware using functional parameters

Function	Argument Type	Description	Default
WithNext	func(*fiber.Ctx) bool	Define a function to skip this middleware when returned true .	nil
WithTracerProvider	oteltrace.TracerProvider	Specifies a tracer provider to use for creating a tracer.	nil - the global tracer provider is used
WithMeterProvider	otelmetric.MeterProvider	Specifies a meter provider to use for reporting.	nil - the global meter provider is used
WithPort	int	Specifies the value to use when setting the net.host.port attribute on metrics/spans.	Defaults to (80 for http, 443 for https)
WithPropagators	propagation.TextMapPropagator	Specifies propagators to use for extracting information from the HTTP requests.	If none are specified, global ones will be used
WithServerName	string	Specifies the value to use when setting the http.server_name attribute on metrics/spans.	-
WithSpanNameFormatter	func(*fiber.Ctx) string	Takes a function that will be called on every request and the returned string will become the span Name.	Default formatter returns the route pathRaw
WithCustomAttributes	func(*fiber.Ctx) []attribute.KeyValue	Define a function to add custom attributes to the span.	nil
WithCustomMetricAttributes	func(*fiber.Ctx) []attribute.KeyValue	Define a function to add custom attributes to the metrics.	nil
WithCollectClientIP	bool	Specifies whether to collect the client's IP address from the request.	true

Usage

Please refer to example

Example

package main

import (
	"context"
	"errors"
	"log"

	"go.opentelemetry.io/otel/sdk/resource"

	"github.com/gofiber/fiber/v2"

	"github.com/gofiber/contrib/otelfiber"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/attribute"
	stdout "go.opentelemetry.io/otel/exporters/stdout/stdouttrace"

	//"go.opentelemetry.io/otel/exporters/jaeger"
	"go.opentelemetry.io/otel/propagation"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
	oteltrace "go.opentelemetry.io/otel/trace"
)

var tracer = otel.Tracer("fiber-server")

func main() {
	tp := initTracer()
	defer func() {
		if err := tp.Shutdown(context.Background()); err != nil {
			log.Printf("Error shutting down tracer provider: %v", err)
		}
	}()

	app := fiber.New()

	app.Use(otelfiber.Middleware())

	app.Get("/error", func(ctx *fiber.Ctx) error {
		return errors.New("abc")
	})

	app.Get("/users/:id", func(c *fiber.Ctx) error {
		id := c.Params("id")
		name := getUser(c.UserContext(), id)
		return c.JSON(fiber.Map{"id": id, name: name})
	})

	log.Fatal(app.Listen(":3000"))
}

func initTracer() *sdktrace.TracerProvider {
	exporter, err := stdout.New(stdout.WithPrettyPrint())
	if err != nil {
		log.Fatal(err)
	}
	tp := sdktrace.NewTracerProvider(
		sdktrace.WithSampler(sdktrace.AlwaysSample()),
		sdktrace.WithBatcher(exporter),
		sdktrace.WithResource(
			resource.NewWithAttributes(
				semconv.SchemaURL,
				semconv.ServiceNameKey.String("my-service"),
			)),
	)
	otel.SetTracerProvider(tp)
	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
	return tp
}

func getUser(ctx context.Context, id string) string {
	_, span := tracer.Start(ctx, "getUser", oteltrace.WithAttributes(attribute.String("id", id)))
	defer span.End()
	if id == "123" {
		return "otelfiber tester"
	}
	return "unknown"
}