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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package main
import (
"context"
"log"
"net/http"
"strconv"
"github.com/emicklei/go-restful/v3"
"go.opentelemetry.io/contrib/instrumentation/github.com/emicklei/go-restful/otelrestful"
"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 oteltrace.Tracer
type userResource struct{}
func (u userResource) WebService() *restful.WebService {
ws := &restful.WebService{}
ws.Path("/users").
Consumes(restful.MIME_JSON).
Produces(restful.MIME_JSON)
ws.Route(ws.GET("/{user-id}").To(u.getUser).
Param(ws.PathParameter("user-id", "identifier of the user").DataType("integer").DefaultValue("1")).
Writes(user{}). // on the response
Returns(http.StatusOK, "OK", user{}).
Returns(http.StatusNotFound, "Not Found", nil))
return ws
}
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)
}
}()
u := userResource{}
// create the Otel filter
filter := otelrestful.OTelFilter("my-service")
// use it
restful.DefaultContainer.Filter(filter)
restful.DefaultContainer.Add(u.WebService())
_ = 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.Baggage{}, propagation.TraceContext{}))
tracer = otel.GetTracerProvider().Tracer("go-restful-server", oteltrace.WithInstrumentationVersion("0.1"))
return tp, nil
}
func (u userResource) getUser(req *restful.Request, resp *restful.Response) {
uid := req.PathParameter("user-id")
_, span := tracer.Start(req.Request.Context(), "getUser", oteltrace.WithAttributes(attribute.String("id", uid)))
defer span.End()
id, err := strconv.Atoi(uid)
if err == nil && id >= 100 {
_ = resp.WriteEntity(user{id})
return
}
_ = resp.WriteErrorString(http.StatusNotFound, "User could not be found.")
}
type user struct {
ID int `json:"id" description:"identifier of the user"`
}
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