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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"
"go.opentelemetry.io/otel/propagation"
"go.opentelemetry.io/otel/trace"
)
// A Flusher dictates how the instrumentation will attempt to flush
// unexported spans at the end of each Lambda innovation. This is
// very important in asynchronous settings because the Lambda runtime
// may enter a 'frozen' state any time after the invocation completes.
// Should this freeze happen and spans are left unexported, there can be a
// long delay before those spans are exported.
type Flusher interface {
ForceFlush(context.Context) error
}
type noopFlusher struct{}
func (*noopFlusher) ForceFlush(context.Context) error { return nil }
// Compile time check our noopFlusher implements Flusher.
var _ Flusher = &noopFlusher{}
// An EventToCarrier function defines how the instrumentation should
// prepare a TextMapCarrier for the configured propagator to read from. This
// extra step is necessary because Lambda does not have HTTP headers to read
// from and instead stores the headers it was invoked with (including TraceID, etc.)
// as part of the invocation event. If using the AWS XRay tracing then the
// trace information is instead stored in the Lambda environment.
type EventToCarrier func(eventJSON []byte) propagation.TextMapCarrier
func emptyEventToCarrier([]byte) propagation.TextMapCarrier {
return propagation.HeaderCarrier{}
}
// Compile time check our emptyEventToCarrier implements EventToCarrier.
var _ EventToCarrier = emptyEventToCarrier
// Option applies a configuration option.
type Option interface {
apply(*config)
}
type optionFunc func(*config)
func (o optionFunc) apply(c *config) {
o(c)
}
type config struct {
// TracerProvider is the TracerProvider which will be used
// to create instrumentation spans
// The default value of TracerProvider the global otel TracerProvider
// returned by otel.GetTracerProvider()
TracerProvider trace.TracerProvider
// Flusher is the mechanism used to flush any unexported spans
// each Lambda Invocation to avoid spans being unexported for long
// when periods of time if Lambda freezes the execution environment
// The default value of Flusher is a noop Flusher, using this
// default can result in long data delays in asynchronous settings
Flusher Flusher
// EventToCarrier is the mechanism used to retrieve the TraceID
// from the event or environment and generate a TextMapCarrier which
// can then be used by a Propagator to extract the TraceID into our context
// The default value of eventToCarrier is emptyEventToCarrier which returns
// an empty HeaderCarrier, using this default will cause new spans to be part
// of a new Trace and have no parent past our Lambda instrumentation span
EventToCarrier EventToCarrier
// Propagator is the Propagator which will be used
// to extract Trace info into the context
// The default value of Propagator the global otel Propagator
// returned by otel.GetTextMapPropagator()
Propagator propagation.TextMapPropagator
}
// WithTracerProvider configures the TracerProvider used by the
// instrumentation.
//
// By default, the global TracerProvider is used.
func WithTracerProvider(tracerProvider trace.TracerProvider) Option {
return optionFunc(func(c *config) {
c.TracerProvider = tracerProvider
})
}
// WithFlusher sets the used flusher.
func WithFlusher(flusher Flusher) Option {
return optionFunc(func(c *config) {
c.Flusher = flusher
})
}
// WithEventToCarrier sets the used EventToCarrier.
func WithEventToCarrier(eventToCarrier EventToCarrier) Option {
return optionFunc(func(c *config) {
c.EventToCarrier = eventToCarrier
})
}
// WithPropagator configures the propagator used by the instrumentation.
//
// By default, the global TextMapPropagator will be used.
func WithPropagator(propagator propagation.TextMapPropagator) Option {
return optionFunc(func(c *config) {
c.Propagator = propagator
})
}
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