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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package otellambda // import "go.opentelemetry.io/contrib/instrumentation/github.com/aws/aws-lambda-go/otellambda"
import (
"context"
"log"
"os"
"strings"
"github.com/aws/aws-lambda-go/lambdacontext"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/attribute"
semconv "go.opentelemetry.io/otel/semconv/v1.21.0"
"go.opentelemetry.io/otel/trace"
)
const (
// ScopeName is the instrumentation scope name.
ScopeName = "go.opentelemetry.io/contrib/instrumentation/github.com/aws/aws-lambda-go/otellambda"
)
var errorLogger = log.New(log.Writer(), "OTel Lambda Error: ", 0)
type instrumentor struct {
configuration config
resAttrs []attribute.KeyValue
tracer trace.Tracer
}
func newInstrumentor(opts ...Option) instrumentor {
cfg := config{
TracerProvider: otel.GetTracerProvider(),
Flusher: &noopFlusher{},
EventToCarrier: emptyEventToCarrier,
Propagator: otel.GetTextMapPropagator(),
}
for _, opt := range opts {
opt.apply(&cfg)
}
return instrumentor{
configuration: cfg,
tracer: cfg.TracerProvider.Tracer(ScopeName, trace.WithInstrumentationVersion(Version())),
resAttrs: []attribute.KeyValue{},
}
}
// Logic to start OTel Tracing.
func (i *instrumentor) tracingBegin(ctx context.Context, eventJSON []byte) (context.Context, trace.Span) {
// Add trace id to context
mc := i.configuration.EventToCarrier(eventJSON)
ctx = i.configuration.Propagator.Extract(ctx, mc)
var span trace.Span
spanName := os.Getenv("AWS_LAMBDA_FUNCTION_NAME")
var attributes []attribute.KeyValue
lc, ok := lambdacontext.FromContext(ctx)
if !ok {
errorLogger.Println("failed to load lambda context from context, ensure tracing enabled in Lambda")
}
if lc != nil {
ctxRequestID := lc.AwsRequestID
attributes = append(attributes, semconv.FaaSInvocationID(ctxRequestID))
// Some resource attrs added as span attrs because lambda
// resource detectors are created before a lambda
// invocation and therefore lack lambdacontext.
// Create these attrs upon first invocation
if len(i.resAttrs) == 0 {
ctxFunctionArn := lc.InvokedFunctionArn
attributes = append(attributes, semconv.AWSLambdaInvokedARN(ctxFunctionArn))
arnParts := strings.Split(ctxFunctionArn, ":")
if len(arnParts) >= 5 {
attributes = append(attributes, semconv.CloudAccountID(arnParts[4]))
}
}
attributes = append(attributes, i.resAttrs...)
}
ctx, span = i.tracer.Start(ctx, spanName, trace.WithSpanKind(trace.SpanKindServer), trace.WithAttributes(attributes...))
return ctx, span
}
// Logic to wrap up OTel Tracing.
func (i *instrumentor) tracingEnd(ctx context.Context, span trace.Span) {
span.End()
// force flush any tracing data since lambda may freeze
err := i.configuration.Flusher.ForceFlush(ctx)
if err != nil {
errorLogger.Println("failed to force a flush, lambda may freeze before instrumentation exported: ", err)
}
}
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