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

Property	Type	Description	Default
Next	func(*fiber.Ctx) bool	Define a function to skip this middleware when returned trueRequired - Rego quer	nil
TracerProvider	oteltrace.TracerProvider	Specifies a tracer provider to use for creating a tracer	nil - the global tracer provider is used
MeterProvider	otelmetric.MeterProvider	Specifies a meter provider to use for reporting	nil - the global meter provider is used
Port	*int	Specifies the value to use when setting the net.host.port attribute on metrics/spans	Required: If not default (80 for http, 443 for https)
Propagators	propagation.TextMapPropagator	Specifies propagators to use for extracting information from the HTTP requests	If none are specified, global ones will be used
ServerName	*string	specifies the value to use when setting the http.server_name attribute on metrics/spans	-
SpanNameFormatter	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
CustomAttributes	func(*fiber.Ctx) []attribute.KeyValue	Define a function to add custom attributes to the span	nil

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"
}