utils.go

Documentation: k8s.io/component-base/tracing

     1  /*
     2  Copyright 2021 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package tracing
    18  
    19  import (
    20  	"context"
    21  	"net/http"
    22  
    23  	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
    24  	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
    25  	"go.opentelemetry.io/otel/propagation"
    26  	"go.opentelemetry.io/otel/sdk/resource"
    27  	sdktrace "go.opentelemetry.io/otel/sdk/trace"
    28  	semconv "go.opentelemetry.io/otel/semconv/v1.17.0"
    29  	oteltrace "go.opentelemetry.io/otel/trace"
    30  
    31  	"k8s.io/client-go/transport"
    32  	"k8s.io/component-base/tracing/api/v1"
    33  )
    34  
    35  // TracerProvider is an OpenTelemetry TracerProvider which can be shut down
    36  type TracerProvider interface {
    37  	oteltrace.TracerProvider
    38  	Shutdown(context.Context) error
    39  }
    40  
    41  type noopTracerProvider struct {
    42  	oteltrace.TracerProvider
    43  }
    44  
    45  func (n *noopTracerProvider) Shutdown(context.Context) error {
    46  	return nil
    47  }
    48  
    49  func NewNoopTracerProvider() TracerProvider {
    50  	return &noopTracerProvider{TracerProvider: oteltrace.NewNoopTracerProvider()}
    51  }
    52  
    53  // NewProvider creates a TracerProvider in a component, and enforces recommended tracing behavior
    54  func NewProvider(ctx context.Context,
    55  	tracingConfig *v1.TracingConfiguration,
    56  	addedOpts []otlptracegrpc.Option,
    57  	resourceOpts []resource.Option,
    58  ) (TracerProvider, error) {
    59  	if tracingConfig == nil {
    60  		return NewNoopTracerProvider(), nil
    61  	}
    62  	opts := append([]otlptracegrpc.Option{}, addedOpts...)
    63  	if tracingConfig.Endpoint != nil {
    64  		opts = append(opts, otlptracegrpc.WithEndpoint(*tracingConfig.Endpoint))
    65  	}
    66  	opts = append(opts, otlptracegrpc.WithInsecure())
    67  	exporter, err := otlptracegrpc.New(ctx, opts...)
    68  	if err != nil {
    69  		return nil, err
    70  	}
    71  	res, err := resource.New(ctx, resourceOpts...)
    72  	if err != nil {
    73  		return nil, err
    74  	}
    75  
    76  	// sampler respects parent span's sampling rate or
    77  	// otherwise never samples.
    78  	sampler := sdktrace.NeverSample()
    79  	// Or, emit spans for a fraction of transactions
    80  	if tracingConfig.SamplingRatePerMillion != nil && *tracingConfig.SamplingRatePerMillion > 0 {
    81  		sampler = sdktrace.TraceIDRatioBased(float64(*tracingConfig.SamplingRatePerMillion) / float64(1000000))
    82  	}
    83  	// batch span processor to aggregate spans before export.
    84  	bsp := sdktrace.NewBatchSpanProcessor(exporter)
    85  	tp := sdktrace.NewTracerProvider(
    86  		sdktrace.WithSampler(sdktrace.ParentBased(sampler)),
    87  		sdktrace.WithSpanProcessor(bsp),
    88  		sdktrace.WithResource(res),
    89  	)
    90  	return tp, nil
    91  }
    92  
    93  // WithTracing adds tracing to requests if the incoming request is sampled
    94  func WithTracing(handler http.Handler, tp oteltrace.TracerProvider, spanName string) http.Handler {
    95  	opts := []otelhttp.Option{
    96  		otelhttp.WithPropagators(Propagators()),
    97  		otelhttp.WithTracerProvider(tp),
    98  	}
    99  	wrappedHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
   100  		// Add the http.target attribute to the otelhttp span
   101  		// Workaround for https://github.com/open-telemetry/opentelemetry-go-contrib/issues/3743
   102  		if r.URL != nil {
   103  			oteltrace.SpanFromContext(r.Context()).SetAttributes(semconv.HTTPTarget(r.URL.RequestURI()))
   104  		}
   105  		handler.ServeHTTP(w, r)
   106  	})
   107  	// With Noop TracerProvider, the otelhttp still handles context propagation.
   108  	// See https://github.com/open-telemetry/opentelemetry-go/tree/main/example/passthrough
   109  	return otelhttp.NewHandler(wrappedHandler, spanName, opts...)
   110  }
   111  
   112  // WrapperFor can be used to add tracing to a *rest.Config.
   113  // Example usage:
   114  // tp := NewProvider(...)
   115  // config, _ := rest.InClusterConfig()
   116  // config.Wrap(WrapperFor(tp))
   117  // kubeclient, _ := clientset.NewForConfig(config)
   118  func WrapperFor(tp oteltrace.TracerProvider) transport.WrapperFunc {
   119  	return func(rt http.RoundTripper) http.RoundTripper {
   120  		opts := []otelhttp.Option{
   121  			otelhttp.WithPropagators(Propagators()),
   122  			otelhttp.WithTracerProvider(tp),
   123  		}
   124  		// With Noop TracerProvider, the otelhttp still handles context propagation.
   125  		// See https://github.com/open-telemetry/opentelemetry-go/tree/main/example/passthrough
   126  		return otelhttp.NewTransport(rt, opts...)
   127  	}
   128  }
   129  
   130  // Propagators returns the recommended set of propagators.
   131  func Propagators() propagation.TextMapPropagator {
   132  	return propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{})
   133  }
   134
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