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// Copyright 2022 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package embed
import (
"context"
"fmt"
"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
"go.opentelemetry.io/otel/propagation"
"go.opentelemetry.io/otel/sdk/resource"
tracesdk "go.opentelemetry.io/otel/sdk/trace"
semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
"go.uber.org/zap"
)
const maxSamplingRatePerMillion = 1000000
func validateTracingConfig(samplingRate int) error {
if samplingRate < 0 {
return fmt.Errorf("tracing sampling rate must be positive")
}
if samplingRate > maxSamplingRatePerMillion {
return fmt.Errorf("tracing sampling rate must be less than %d", maxSamplingRatePerMillion)
}
return nil
}
type tracingExporter struct {
exporter tracesdk.SpanExporter
opts []otelgrpc.Option
provider *tracesdk.TracerProvider
}
func newTracingExporter(ctx context.Context, cfg *Config) (*tracingExporter, error) {
exporter, err := otlptracegrpc.New(ctx,
otlptracegrpc.WithInsecure(),
otlptracegrpc.WithEndpoint(cfg.ExperimentalDistributedTracingAddress),
)
if err != nil {
return nil, err
}
res, err := resource.New(ctx,
resource.WithAttributes(
semconv.ServiceNameKey.String(cfg.ExperimentalDistributedTracingServiceName),
),
)
if err != nil {
return nil, err
}
if resWithIDKey := determineResourceWithIDKey(cfg.ExperimentalDistributedTracingServiceInstanceID); resWithIDKey != nil {
// Merge resources into a new
// resource in case of duplicates.
res, err = resource.Merge(res, resWithIDKey)
if err != nil {
return nil, err
}
}
traceProvider := tracesdk.NewTracerProvider(
tracesdk.WithBatcher(exporter),
tracesdk.WithResource(res),
tracesdk.WithSampler(
tracesdk.ParentBased(determineSampler(cfg.ExperimentalDistributedTracingSamplingRatePerMillion)),
),
)
options := []otelgrpc.Option{
otelgrpc.WithPropagators(
propagation.NewCompositeTextMapPropagator(
propagation.TraceContext{},
propagation.Baggage{},
),
),
otelgrpc.WithTracerProvider(
traceProvider,
),
}
cfg.logger.Debug(
"distributed tracing enabled",
zap.String("address", cfg.ExperimentalDistributedTracingAddress),
zap.String("service-name", cfg.ExperimentalDistributedTracingServiceName),
zap.String("service-instance-id", cfg.ExperimentalDistributedTracingServiceInstanceID),
)
return &tracingExporter{
exporter: exporter,
opts: options,
provider: traceProvider,
}, nil
}
func (te *tracingExporter) Close(ctx context.Context) {
if te.provider != nil {
te.provider.Shutdown(ctx)
}
if te.exporter != nil {
te.exporter.Shutdown(ctx)
}
}
func determineSampler(samplingRate int) tracesdk.Sampler {
sampler := tracesdk.NeverSample()
if samplingRate == 0 {
return sampler
}
return tracesdk.TraceIDRatioBased(float64(samplingRate) / float64(maxSamplingRatePerMillion))
}
// As Tracing service Instance ID must be unique, it should
// never use the empty default string value, it's set if
// if it's a non empty string.
func determineResourceWithIDKey(serviceInstanceID string) *resource.Resource {
if serviceInstanceID != "" {
return resource.NewSchemaless(
(semconv.ServiceInstanceIDKey.String(serviceInstanceID)),
)
}
return nil
}
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