upgradeNotes:
  - title: Default tracing to `zipkin.istio-system.svc` removed
    content: |
      In previous versions of Istio, tracing was automatically configured to send traces to `zipkin.istio-system.svc`.
      This default setting has been removed; users will need to explicitly configure where to send traces moving forward.

      `istioctl x precheck --from-version=1.21` can automatically detect if you may be impacted by this change.

						if err != nil {
							return fmt.Errorf("cannot get traces from zipkin: %v", err)
						}
						if !tracing.VerifyEchoTraces(ctx, appNsInst.Name(), cluster.Name(), traces) {
							return errors.New("cannot find expected traces")
						}
						return nil
					}, retry.Delay(3*time.Second), retry.Timeout(80*time.Second))
				})

			}
		})

```yaml
spec:
  ports:
    - name: grpc-otlp
      port: 4317
      protocol: TCP
      targetPort: 4317
```

Otherwise the traces may not be reported.

## Update mesh config

	Admission                  *AdmissionOptions
	// API Server Egress Selector is used to control outbound traffic from the API Server
	EgressSelector *EgressSelectorOptions
	// Traces contains options to control distributed request tracing.
	Traces *TracingOptions
}

func NewRecommendedOptions(prefix string, codec runtime.Codec) *RecommendedOptions {
	sso := NewSecureServingOptions()

const headerFmt = "go 1.%d trace\x00\x00\x00"

// ReadHeader reads the version of the trace out of the trace file's
// header, whose prefix must be present in v.
func ReadHeader(r io.Reader) (Version, error) {
	var v Version
	_, err := fmt.Fscanf(r, headerFmt, &v)
	if err != nil {
		return v, fmt.Errorf("bad file format: not a Go execution trace?")
	}
	if !v.Valid() {

  // Initialize concrete function traces.
  const RepeatedPtrField<FunctionDef> function_defs =
      tf_package->GetFunctionDefs();
  absl::flat_hash_map<std::string, AbstractFunctionPtr> traces;
  for (auto& fdef : function_defs) {
    AbstractFunctionPtr trace(new GraphFunction(fdef), /*add_ref=*/false);
    traces[fdef.signature().name()] = trace;
  }

  // Setup polymorphic functions and wrap in Callables.

const (
	// instrumentationScope is the name of OpenTelemetry instrumentation scope
	instrumentationScope = "istio.io/istio"
)

func tracer() traceapi.Tracer {
	return otel.Tracer(instrumentationScope)
}

// Initialize starts the tracing provider. This must be called before any traces are created or traces will be discarded.
// Returned is a shutdown function that should be called to ensure graceful shutdown.
func Initialize() (func(), error) {

It can interpret and emit execution traces in its wire format as well as a
bespoke but simple text format.

The readers and writers in this package perform no validation on or ordering of
the input, and so are generally unsuitable for analysis. However, they're very
useful for testing and debugging the tracer in the runtime and more sophisticated
trace parsers.

# Text format specification

	"cmd/internal/telemetry"
	"flag"
	"fmt"
	"internal/trace"
	"internal/trace/raw"
	"internal/trace/traceviewer"
	"io"
	"log"
	"net"
	"net/http"
	_ "net/http/pprof" // Required to use pprof
	"os"
	"sync/atomic"
	"time"
)

const usageMessage = "" +
	`Usage of 'go tool trace':
Given a trace file produced by 'go test':
	go test -trace=trace.out pkg

Open a web browser displaying trace:

	"os"
	"regexp"
	"strings"

	"internal/trace"
	"internal/trace/event"
	"internal/trace/event/go122"
	"internal/trace/raw"
	"internal/trace/version"
	"internal/txtar"
)

func Main(f func(*Trace)) {
	// Create an output file.
	out, err := os.Create(os.Args[1])
	if err != nil {
		panic(err.Error())
	}
	defer out.Close()

	// Create a new trace.
	trace := NewTrace()

	// Call the generator.