otelmux

Documentation

Overview

Package otelmux instruments the github.com/gorilla/mux package.

Currently only the routing of a received message can be instrumented. To do it, use the Middleware function.

Example

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"

	"github.com/gorilla/mux"

	"go.opentelemetry.io/contrib/instrumentation/github.com/gorilla/mux/otelmux"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/attribute"
	stdout "go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
	"go.opentelemetry.io/otel/propagation"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	oteltrace "go.opentelemetry.io/otel/trace"
)

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

func main() {
	tp, err := initTracer()
	if err != nil {
		log.Fatal(err)
	}
	defer func() {
		if err := tp.Shutdown(context.Background()); err != nil {
			log.Printf("Error shutting down tracer provider: %v", err)
		}
	}()
	r := mux.NewRouter()
	r.Use(otelmux.Middleware("my-server"))
	r.HandleFunc("/users/{id:[0-9]+}", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		vars := mux.Vars(r)
		id := vars["id"]
		name := getUser(r.Context(), id)
		reply := fmt.Sprintf("user %s (id %s)\n", name, id)
		_, _ = w.Write(([]byte)(reply))
	}))
	http.Handle("/", r)
	_ = http.ListenAndServe(":8080", nil) //nolint:gosec // Ignoring G114: Use of net/http serve function that has no support for setting timeouts.
}

func initTracer() (*sdktrace.TracerProvider, error) {
	exporter, err := stdout.New(stdout.WithPrettyPrint())
	if err != nil {
		return nil, err
	}
	tp := sdktrace.NewTracerProvider(
		sdktrace.WithSampler(sdktrace.AlwaysSample()),
		sdktrace.WithBatcher(exporter),
	)
	otel.SetTracerProvider(tp)
	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
	return tp, nil
}

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 "otelmux tester"
	}
	return "unknown"
}

Index

• Constants
• func Middleware(service string, opts ...Option) mux.MiddlewareFunc
• func Version() string
• type Filter
• type Option
  • func WithFilter(f Filter) Option
  • func WithMeterProvider(provider metric.MeterProvider) Option
  • func WithMetricAttributesFn(metricAttributesFn func(r *http.Request) []attribute.KeyValue) Option
  • func WithPropagators(propagators propagation.TextMapPropagator) Option
  • func WithPublicEndpoint() Option
  • func WithPublicEndpointFn(fn func(*http.Request) bool) Option
  • func WithSpanNameFormatter(fn func(routeName string, r *http.Request) string) Option
  • func WithTracerProvider(provider oteltrace.TracerProvider) Option

Examples

• Package

Constants

const (
	// ScopeName is the instrumentation scope name.
	ScopeName = "go.opentelemetry.io/contrib/instrumentation/github.com/gorilla/mux/otelmux"
)

Functions

func Middleware

func Middleware(service string, opts ...Option) mux.MiddlewareFunc

Middleware sets up a handler to start tracing the incoming requests. The service parameter should describe the name of the (virtual) server handling the request.

func Version

func Version() string

Version is the current release version of the gorilla/mux instrumentation.

Types

type Filter

type Filter func(*http.Request) bool

Filter is a predicate used to determine whether a given http.request should be traced. A Filter must return true if the request should be traced.

type Option

type Option interface {
	// contains filtered or unexported methods
}

Option specifies instrumentation configuration options.

func WithFilter

func WithFilter(f Filter) Option

WithFilter adds a filter to the list of filters used by the handler. If any filter indicates to exclude a request then the request will not be traced. All filters must allow a request to be traced for a Span to be created. If no filters are provided then all requests are traced. Filters will be invoked for each processed request, it is advised to make them simple and fast.

func WithMeterProvider

func WithMeterProvider(provider metric.MeterProvider) Option

WithMeterProvider specifies a meter provider to use for creating a metric. If none is specified, the global provider is used.

func WithMetricAttributesFn

func WithMetricAttributesFn(metricAttributesFn func(r *http.Request) []attribute.KeyValue) Option

WithMetricAttributesFn returns an Option to set a function that maps an HTTP request to a slice of attribute.KeyValue. These attributes will be included in metrics for every request.

func WithPropagators

func WithPropagators(propagators propagation.TextMapPropagator) Option

WithPropagators specifies propagators to use for extracting information from the HTTP requests. If none are specified, global ones will be used.

func WithPublicEndpoint

func WithPublicEndpoint() Option

WithPublicEndpoint configures the Handler to link the span with an incoming span context. If this option is not provided, then the association is a child association instead of a link.

func WithPublicEndpointFn

func WithPublicEndpointFn(fn func(*http.Request) bool) Option

WithPublicEndpointFn runs with every request, and allows conditionally configuring the Handler to link the span with an incoming span context. If this option is not provided or returns false, then the association is a child association instead of a link. Note: WithPublicEndpoint takes precedence over WithPublicEndpointFn.

func WithSpanNameFormatter

func WithSpanNameFormatter(fn func(routeName string, r *http.Request) string) Option

WithSpanNameFormatter specifies a function to use for generating a custom span name. By default, the route name (path template or regexp) is used. The route name is provided so you can use it in the span name without needing to duplicate the logic for extracting it from the request.

func WithTracerProvider

func WithTracerProvider(provider oteltrace.TracerProvider) Option

WithTracerProvider specifies a tracer provider to use for creating a tracer. If none is specified, the global provider is used.